Dragon 32, Dragon 64
| Dragon 32, Dragon 64 | |
|---|---|
   |
|
| Manufacturer | Dragon Data Ltd. Tano Microcomputer Products Corp. Eurohard SA |
| Type | Home computers |
| publication |
|
| End of production | 1986 |
| Factory price |
199 £
399 $ |
| processor | Motorola 6809E @ 0.89 MHz |
| random access memory | 32/64 KB |
| graphic | Motorola 6847 |
| Sound | 1 voice, mono, 5 octaves |
| Disk | Floppy disks, cartridges , compact cassettes , mini cassettes |
| operating system | Dragon BIOS, Optional: Delta DOS, Dragon DOS, OS-9, FLEX |
| predecessor | - |
| successor | - |
Dragon 32 and Dragon 64 are on the 6809E - microprocessor -based home computer of the Welsh manufacturer Dragon Data Ltd. The differences in the naming of the two models relate to the configuration of the main memory ( RAM ) in the delivery state, namely 32 or 64 kilobytes (KB).
The Dragon 32 was designed at the end of 1981 as an above-average powerful device for the lower price segment of the rapidly growing British home computer market. In contrast to its direct competition models, the Sinclair ZX Spectrum and Acorn BBC Micro with Z80 and 6502 microprocessors, Dragon Data Ltd. his hopes for the 6809 microprocessor, which has received little attention in Europe. Its use was mainly motivated by the greater efficiency and not least by favorable sales conditions on the part of the manufacturer Motorola . The great similarity of the first prototypes of the Dragon 32 with the US American Tandy Color Computer initially led to patent infringements, which could be cleared up by minor technical modifications by the start of production. In addition, Dragon Data Ltd. his computer with an extended version of the Microsoft BASIC programming language , which allows easy use of the extensive graphics options.
The Dragon 32 was launched in Great Britain in August 1982. In Germany, the device was brought onto the market by Noris Computer-Vertriebs- GmbH (Norcom) from the beginning of 1983. The Dragon 64 was added in September in the US and in November in Europe. Both were owned by Dragon Data Ltd. until 1984 . and its US licensee Tano Microcomputer Products Corp. produced. Following the bankruptcy of Dragon Data Ltd. the Spanish company Eurohard SA continued the production with modified devices until May 1986.
Dragon 32 and 64 are largely software compatible with the various models of the Tandy Color Computer.
history
To avert economic difficulties, the British toy manufacturer Mettoy decided in the early 1980s to enter the rapidly growing, lucrative home computer market with its own device. The subsidiary Dragon Data Ltd., founded specifically for this purpose in 1981 and which was also to give the product its name, was entrusted with the implementation of the project.
Development and prototypes
One of the requirements for the contractors of Mettoy in October 1981 developer of PA Technology (PAT) of Cambridge was the demand for an efficient and economical alternative to the then-popular UK home computers with an on the Z80 - or 6502 - microprocessor -based system architecture . The decision was made in favor of the 6809E microprocessor from Motorola , which was little noticed by the European computer industry and promised outstanding graphics capabilities for the computer to be developed. Furthermore, for reasons of efficiency, a standard chipset with memory management and peripheral components from Motorola should be used for its operation, which was also used in the Tandy Color Computer, which was introduced in the USA in 1980. In order to avoid foreseeable problems under patent law with this replica and in view of ease of use, the developers changed some technical details. For example, the printer interface was implemented in parallel , the use of 64 KB RAM was enabled and Tandy's unwieldy rubber keyboard was replaced by a full-fledged typewriter keyboard. Similar to the products of other manufacturers, the computer should have a built-in higher programming language . The choice fell on a specially adapted Extended Microsoft BASIC , which allows the simple use of high-resolution graphics.
The finished pre-series sample of the Dragon 32 with the internal code name "Pippin" and 16 KB RAM was presented to the Mettoy management at Christmas 1981 after a development time of around three months, approved and then brought to series production by PA Technology of Cambridge. Having already much of the first 10,000 motherboards had been prepared by the supplier Race Electronics, took place in particular with regard to the competing ZX Spectrum of Sinclair and the BBC Micro Acorn shortly before delivery of Mettoys final assembly factory in Wales Swansea subsequent increase of RAM to another 16 KB to a total of 32 KB.
Marketing of the Dragon 32
The first devices advertised as “family computers” went to UK stores in various department store chains in August 1982 for £ 199 . Due to the good technical equipment of the Dragon 32 and delivery difficulties at Commodore, Sinclair and Acorn , around 32,000 devices were sold in the first six months of sales, especially during the Christmas business. Inspired by this great success, work has meanwhile been carried out on opening up the entire European market. Branches such as Dragon Data (France) were set up especially for this purpose and contracts were concluded with external distributors such as Noris Computer Vertriebs-GmbH (Norcom), which was won over for sales in Germany. The Finnish licensee Finlux represented a special feature, who provided his devices with their own Finlux nameplate.
Despite good computer sales, the economic difficulties for Mettoy had worsened towards the end of 1982, so that the majority shares of the home computer division Dragon Data Ltd. had to be sold in November 1982 to a consortium led by the technology investor Pru-tech; only 18.61 percent of the shares in the newly founded corporation Dragon Data Ltd. stayed with Mettoy. With the help of the brought in fresh capital amounting to 2.4 million pounds sterling (about 9 million DM), the production capacity could be expanded by a new plant in Kenfig near Port Talbot and work continued on the development of successor models and a floppy disk drive for the Dragon 32 . In addition, Dragon Data Ltd. For example, by presenting its devices at international trade fairs, it was eyeing for new non-European sales markets and production facilities and promoting their development. By mid-1983, a total of over 100,000 devices had been sold to customers, mainly in Great Britain. The Dragon 32 had established itself as a fixture on the British home computer market just one year after its appearance, and sales in July 1983 were only exceeded by the undisputed market leader Sinclair ZX Spectrum.
From autumn 1983 the increase in production volume, a lack of up-to-date software and strong competition from the Commodore 64 and Atari 600XL led to market saturation; the targeted sales figures were clearly missed. Pre-manufactured devices could not be sold and a new capital injection of 2.5 million pounds sterling by Pru-tech, which with personnel changes in the management of Dragon Data Ltd. had become necessary in September 1983. The new management level immediately decided to expand the product range, whereby the early production of the Dragon 64, which is already in development, with 64 KB RAM and RS-232 connection, and that of the Dragon floppy disk system enjoyed particular priority.
Marketing of the Dragon 64
Sales of the Dragon 64 began in the United States in September 1983 and a few months later in Europe. A variant of the Dragon 32 with an additional 32 KB RAM was then offered and buyers of the old model were offered a corresponding update of their devices at the local dealers. Upgrading proved to be too costly for both the factories and the customer service staff. From the end of December, in time for the Christmas business, Dragon Data Ltd. the owners of a Dragon 32 therefore have to exchange their device for a Dragon 64 at an additional cost. The exchange campaign was to be supported by the publication of technical documentation in the form of the book Inside the Dragon and the introduction of the long-awaited Unix- like operating system OS-9 , which requires a 64 KB Dragon computer with a floppy disk drive to operate. In spite of the powerful programming languages and application programs that were now available, many Dragon-32 owners were opposed to the exchange offer.
Due to the lower than expected acceptance of the Dragon 64 in the home computer market, sales collapsed drastically until the beginning of 1984. In order to avoid further foreseeable losses of market share, in February 1984 the main shareholders of Dragon Data Ltd. the marketing of Dragon products was transferred to the external General Electric Company (GEC), which is closely related to Pru-tech . The advertising campaigns initiated by GEC in magazines and the new brand name GEC DRAGON introduced in Great Britain for the Dragon 64 computers should bring about the turning point.
In West Germany the Dragon 64 and the Dragon floppy disk drive came onto the market in the spring of 1984 for 1,290 DM and 1,300 DM respectively, initially exclusively through Friedrich M. Hunold; the surcharge for the exchange of a Dragon 32, which was also offered in West Germany, was 348 DM at that time. However, the Dragon 64 was only presented to a broader public in West Germany in May 1984 at the Hobby-tronic trade fair. Probably as a result of the associated increased demand, the company Norcom, with its sales network already established for the Dragon 32, took over the sale of the Dragon 64 in West Germany shortly afterwards.
Dragon Data Ltd. bankruptcy and takeover by Eurohard SA
Not trusting the increased marketing efforts of GEC, important British wholesale customers such as the department store chain British Home Stores Ltd. dropped out. the Dragon computers either completely from the sales program or supplemented this, for example at the drugstore chain Boots UK Ltd. for other competing products. Sales in the USA by the licensee Tano were also far below GEC's expectations - fewer than 5000 devices were sold and the economic targets were clearly missed. At the same time, enormous costs were incurred due to ongoing production operations and the development of new computer models promoted by GEC, so that within a short period of time, high debts again accumulated. However, the main shareholders around Pru-tech refused to serve them with further financial aid, so that in mid-June 1984 Dragon Data Ltd. went bankrupt. became inevitable.
Although a total of around 200,000 Dragon computers had found buyers worldwide by the time of the bankruptcy and there was thus enough potential customers available for further products and programs, the takeover negotiations with the numerous interested parties proved difficult. At the end of July 1984, the bankruptcy estate was taken over by the Spanish Eurohard SA, which had been completely unknown in the home computer industry, for an estimated £ 1 million, after negotiations with, for example, Tandy Corporation had failed shortly before. All production lines and development departments from Port Talbot were relocated to Spain from the new owner. GEC was responsible for selling out stocks of around 13,000 pieces of equipment (computers and floppy disk drives) valued at an estimated £ 4 million to £ 6 million, and was also responsible for future UK sales until spring 1985. Touchmaster Limited, which was previously spun off by former Dragon employees, acted as a service provider for existing customers and a contact for software developers.
The Spanish production facilities started production in November 1984 and initially supplied the European market with technically unchanged Dragon devices. Several new releases such as the Dragon 200, Dragon 200-E and Dragon MSX (new development with Z80 CPU, incompatible with Dragon 32 and 64) followed in 1985 and rounded off the product range. From April 1985 on, the distributor Compusense Ltd. supplying Great Britain, the largest sales market alongside Spain. In the first year of production, Eurohard SA sold around 17,000 devices across Europe, and around another 20,000 devices went to public educational institutions in Spain. The 16-bit home computers such as the Amiga and Atari ST , which appeared in the summer of 1985 , slackened interest in the technically outdated Dragon devices. As a result of the associated decline in sales, production was gradually reduced with a daily output of 500 devices since 1984 and finally stopped completely in May 1986 after extensive sales from the end of 1985.
- The nameplates of the various Dragon models at a glance
Dragon 32
Dragon 64
Dragon 64 by Tano
Dragon 64 as a GEC model
Dragon 32 licensing model from Finlux
Packaging label for the user package offered by FarmFax, which, in addition to the Dragon 32 computer, contained application programs specially tailored to agricultural businesses
Technical details
The basic devices contain two boards with the various assemblies, keyboard, peripheral connections, screen output and voltage regulation for the external power supply unit. The computer unit with 6809E- CPU (English central processing unit ), the working memory (RAM) and read-only memory (ROM), peripheral connections and the two parallel interfaces for expansions are located on the motherboard .
CPU
The hardware architecture of the Dragon computers is based on a 6809E microprocessor from Motorola. Thanks to the internal processing width of 16 bits , this CPU is significantly more powerful, especially in the area of arithmetic operations, than the higher-clocked Z80 or 6502 microprocessors, such as those built into the direct competing products Sinclair ZX81 , Apple II or Atari 400/800 .
The 6809E-CPU can access an address space of 65536 bytes , which also defines the theoretically possible upper limit of the main memory of 64 kilobytes (KB). For practical reasons, it is common for addresses instead of decimal notation , the hexadecimal to use. This is usually preceded by a $ symbol to make it easier to distinguish. The addresses from 0 to 65535 in decimal notation correspond to addresses $ 0000 to $ FFFF in the hexadecimal system.
Memory allocation, RAM and ROM, expansion slot
The address space that can be used by the CPU in the Dragon 32 is essentially divided into four different sections: 32 KB RAM ($ 0000– $ 7FFF), 16 KB ROM ($ 8000– $ BFFF), a free address area of around 16 KB ($ C000– $) FEFF) and a block with the hardware registers of the memory management module 6883-SAM ( Synchronous Address Multiplexer ) and the two input / output modules ($ FF00– $ FFFF). All addressing processes of the 6809E-CPU run via the 6883-SAM, the second central processing unit in the Dragon. These ICs , which can be programmed by the user, are also responsible for generating the system clock and for accessing the video memory area in the RAM by the standard 6847-VDC graphics chip ( video display controller ) .
The RAM contains the system variables, the video memory and areas that can be used for programming with the combination of operating system ("BIOS") and BASIC contained in the ROM. Immediately after the ROM is almost 16 KB of unused memory, which in the Dragon 32 is reserved for plug-in modules or other hardware at the expansion slot ("expansion port" or "plug-in module slot"), a parallel interface.
The Dragon 64 has 64 KB of RAM and two 16 KB ROMs, which contain slightly different BASIC versions. After switching on, the first ROM is activated for the 32 mode. There is then 30 KB free RAM available. By entering a command, the second ROM on the Dragon 64 is copied into the RAM area $ C000– $ FEFF, displayed in the area $ 8000– $ BFFF RAM and the copied ROM contents are executed (“bootstrapping”). In 64 mode, 45 KB of RAM are available for programming with BASIC. To visually differentiate between the two operating modes, the screen cursor flashes blue in 64 mode, whereas in 32 mode it flashes in the usual black on a green background.
Graphics, sound, input and output
The 6847-VDC reads out and displays the graphic data on the connected television or monitor. It provides various graphic modes such as text, high-resolution pixel graphics and so-called semi-graphics. Of the eight possible full graphic modes, only five are supported by the built-in BASIC. The highest possible resolution is 256 × 192 pixels in two colors (can be selected from two specified color groups), with lower resolutions up to four colors (from two specified color groups) are possible. In semi-graphic mode, all eight available colors can be displayed at the same time: In text mode (32 × 16 characters), the text characters with a resolution of 8 × 12 points are colored graphic blocks of lower resolution (four blocks of 4 × 6 points or six blocks of 8 × 3 points).
The electronic control signals required by the graphics chip are generated using two 6821 PIA modules ( Peripheral Interface Adapter ) that are also part of Motorola's 6883 standard chipset . The tasks of these two input / output circuits also include reading out the keyboard, handling interrupts , operating the input and output ports, generating sounds ( square wave generator ) and controlling mass storage devices.
The Dragon 64 contains another special component for implementing the RS-232 protocol, the 6551-ACIA ( Asynchronous Communications Interface Adapter ).
Interfaces
An expansion slot, a cassette interface , two joystick connections for analog joysticks , an RGB monitor socket, a TV connection and an RS-232 interface for the Dragon 64 are available as connections to the outside world .
Right side with expansion slot
Rear with power connection, power switch and monitor socket
Left side of the Dragon 32 with HF output to the television, reset button , connections for joysticks, cassette recorder and printer
Periphery
Mass storage
In connection with home computers of the early 1980s, cassette recorders and floppy disk drives were mainly used as mass storage devices, and hard and removable disk drives were increasingly used in the professional environment for personal computers. The cheapest variant of data recording using audio cassettes is i. A. the disadvantage of low data transfer rates and thus long loading times, whereas the much faster and more reliable floppy and disk drives were much more expensive to purchase. When the Dragon was released, only cassette recorders were available for mass storage; diskette systems were only added a few months later.
In the following sections only the most well-known systems should be mentioned.
Cassette recorder
The Dragon computers are factory-fitted with a cassette interface for recording and reading out data using standard cassette recorders . Corresponding compact cassettes serve as storage media . As with the competing Sinclair ZX Spectrum, the standard transfer rate is an average of 1500 bit / s , a high value compared to other contemporary competitive systems, for example from Commodore (300 bit / s) or Atari (600 bit / s).
In early 1984, IKON Computer Products released a data recorder based on mini-cassettes . This Ultra Drive , which is delivered without any additional control buttons except for an eject button, is operated with the aid of an interface connected to the expansion port and the software it contains along with BASIC commands. At a transfer rate of 1200 bit / s, up to 200 KB of data can be stored per cartridge.
Floppy disk systems
As it became known in September 1982, the planned delivery of the diskette system from Dragon Data Ltd. for October 1982 was to take place. due to technical and economic difficulties. The existing high demand from a large number of Dragon users therefore prompted the third-party provider Premier Microsystems Ltd. and Compusense Ltd. to develop own diskette systems by February 1983. In particular, the cheaper one from Premier Microsystems Ltd. Delta Disc System, sold in April 1983, enjoyed great popularity and quickly established itself on the market. Until the Dragon Data Ltd. in September 1983, about 1000 units from Premier Microsystems Ltd. and a few more of his licensee Cumana Ltd. in Great Britain their customers, with which Dragon Data Ltd. not negligible market shares were stolen.
The two incompatible disk systems from Dragon and Premier Microsystems are each operated by plugging a hardware interface (“disc controller”) into the expansion port of the Dragon computer. The interface contains the control electronics for the external drive mechanism connected via a ribbon cable and the associated diskette operating system such as Dragon DOS or Delta DOS. A maximum of 180 KB per 5¼-inch diskette can be stored with the system from Dragon and with the system from Premier Microsystems or Cumana Ltd. Depending on the design of the drive mechanism (40 or 80 tracks, single or double write density, single-sided or double-sided writing), up to 720 KB of data can be saved. The interface, which was also offered separately by Premier Microsystems until the beginning of 1985, not only allows the use of 5¼-inch mechanisms, but also the connection of 8- and 3-inch devices that were also in use at the time.
By using an interface with permanently installed system software, the memory requirement for operating the diskette system could be kept very low, but at the price of an expansion slot blocked for further plug-in modules or peripherals. The OS-9 and FLEX diskette operating systems, which were available from 1984 onwards, are loaded from diskette into the main memory, after which the expansion port is freely available again.
Front view of the Dragon floppy disk drive
Dragon floppy disk drive in side view
Dragon floppy disk drive in rear view
Input devices
In addition to the QWERTY typewriter keyboard with 53 keys (no Escape, Caps and Control keys) and the analog joysticks from Dragon Data Ltd. other devices were available for input. This includes to be connected to the expansion port Maltafel Touch Master tablet or a light pen Trojan LightPen third party.
Extensions
In the course of time, many extensions and conversion kits of various sizes appeared for the Dragon 32 and its successors, although only the most important are listed below.
Improved sound generation and speech output
The Sound Extension Module , available from JCB Microsystems as a plug-in module from August 1983, contains the AY-3-8910 synthesizer component built into many gaming machines and home computers . It has extensive options for sound generation and manipulation and is far superior to the options available in the Dragon ex works. It is controlled conveniently using a special command provided by the plug-in module for the Extended BASIC. The speech synthesis module Speech Synthesis Module , which came onto the market a little earlier, allows the transfer of the words to be spoken in text form with five additional BASIC commands, whereby the number of words that can be generated is unlimited due to the allophone technology used .
Dragon Plus
This from Compusense Ltd. The expansion card manufactured and sold can be connected directly to the motherboard of the computer in a few simple steps. After the upgrade, an additional 64 KB RAM and a 6845 graphics chip with separate video memory and an additional monitor socket for displaying an 80-character text mode (80 × 24 characters) are available. When using the OS-9 or FLEX operating systems, the retrofitted main memory serves as a virtual floppy disk drive (“Ramdisk”) and, in conjunction with the extended text options, enables fast and convenient work, for example with the word processing program Edit + .
The Dragon's Claw
This expansion of Lucidata of Cambridge, introduced in October 1985, provides additional expansion options for the Dragon computers. These include two 20-pin parallel interfaces which, with the appropriate software support, allow the operation of peripheral devices from the BBC microcomputer system on the Dragon 32 or 64, which was widely used in Great Britain at the time . Instead of just one, each Dragon now has several expansion interfaces that can be used simultaneously with the appropriate software such as OS-9 or FLEX. This enables, among other things, the use of more powerful development environments through the simultaneous operation of floppy disk drives and plug-in modules, on which, for example, programming aids such as assemblers or compilers can be located.
Sound extension modules for plugging into the expansion port
Circuit board with synthesizer module, software on ROM and control electronics
Case back
Dragon's Claw module to plug into the expansion port
Case back
software
Simultaneously with the market launch of the Dragon 32 in the summer of 1982, high-quality software titles, including mostly adaptations of popular arcade machine games , were available. In autumn 1982, many programs from independent third-party manufacturers were added, which is primarily due to Dragon Data's less restrictive software policy. Contrary to the customs of the time, Dragon Data renounced common licensing models and gave third-party manufacturers a free hand to develop and sell their own Dragon software, combined with the hope of increased computer sales. Despite the developer-friendly environment and the performance of the microprocessor built into the Dragon, the Dragon computers did not meet with approval from all established European software manufacturers. The main reason for this was a lack of experience in programming the hardly widespread 6809 microprocessor, which made porting the popular computer systems of the time, which were the best sellers, appeared economically unprofitable. For this reason, until the second quarter of 1983, the software of the third-party manufacturers consisted for the most part of license versions of programs of the Tandy Color Computer, which is widely used in America and largely software-compatible. With the introduction of the Dragon 64, manufacturers, above all Dragon Data Ltd. and Compusense Ltd., the offer for the likewise newly published system programs OS-9 and FLEX massively on powerful programming languages and application programs.
As with other home computers of the 1980s, commercial Dragon software was also distributed on various data carriers. The inexpensive compact cassettes, particularly popular with game manufacturers, were, however, very prone to errors due to the high mechanical stress on the magnetic tape, and their use was often associated with long loading times. In the case of the plug-in modules, which are much more expensive to manufacture, the programs contained therein were available immediately after switching on the computer, which was a great advantage in particular for system software and frequently used applications. The floppy disks achieved the best compromise between loading time, reliability and storage capacity, although the expensive floppy disk drives needed to use them were only available about a year after the Dragon 32 was launched.
Another source and popular way of distributing software for Dragon computers was typing in program texts ("listings") in magazines. In addition, a large number of books of different quality, mainly with BASIC exercises and BASIC program collections, were available for the Dragon computers.
Illegal copies ("pirated copies") always made up a large part of the software in circulation and often presented small software developers with existential economic difficulties. As a result, copy protection systems were increasingly used, especially in games, as the best-selling software.
In the following sections only the most popular software is presented.
System programs
The configuration of the Dragon hardware, which also includes the control of the cassette interface, is the responsibility of the operating system - the "firmware". To optimize the interaction with the Extended BASIC interpreter, which is also located on the 16 KB Dragon ROMs, both are very closely interwoven in terms of programming. Additional system programs (“Disc Operating System”, DOS) are required for the operation of diskette systems. These were delivered either on ROM (Delta DOS, Dragon DOS) or floppy disk (OS-9, FLEX).
Operating system (BIOS)
The BIOS of the Dragon computers is based on Motorola's standard software for controlling a 6809-based reference system. In addition to adjustments to support the technical features of the Dragon computers, which also affected the use of the Extended BASIC interpreter, the Dragon developers mainly made improvements to increase performance. For example, through an optimized query of the keyboard entries compared to the Tandy Color Computer, which is also largely based on Motorola's 6809 reference system, the overall processing speed of the Dragon computers was up to 15 percent higher.
Delta DOS and Dragon DOS
Both DOSs were permanently installed on ROMs in the hardware interfaces ("interfaces") of the diskette systems of their manufacturers, Premier Microsystems and Dragon Data Ltd. Each of the systems allows the simultaneous operation of a maximum of four floppy disk drives, whereby the Delta DOS supports extended configuration options for their mechanisms. What they also have in common is the simple integration into the system environment of the Dragon computer by providing new BASIC commands without taking up any additional memory. However, Delta DOS and Dragon DOS are not compatible with each other due to the different electronic floppy disk controller modules built into the interfaces: floppy disks written with Dragon DOS cannot be used with Delta DOS and vice versa.
Delta DOS is characterized by more flexible usage options due to the standard direct access to individual bytes of disk sectors ("random access"). It also has a larger set of commands, better documentation and more intuitive operation. The diskette system operated with Dragon DOS, on the other hand, is faster and was offered cheaper, but only appeared a few months later than its competitor. Dragon DOS requires 32 mode on Dragon 64 computers to operate, which means that only 23 KB of free memory are available. If the full 64 KB RAM of the Dragon 64 is to be used together with the Dragon floppy disk station, either OS-9 or FLEX is required.
Dragon disk interface for plugging into the expansion port
Board with floppy disk controller, software ROM and control electronics
Case back
Delta disk interface for plugging into the expansion port
Board with floppy disk controller, software ROM and control electronics. The free ROM socket can be equipped with additional software such as the assembler Encoder09 .
Case back
OS-9 and FLEX
Shortly after the Dragon 64 entered the market, Dragon Data Ltd. 1983 the near UNIX operating system OS-9 licensed by Microware Systems Corporation . To use it you need at least a Dragon computer with 64 KB RAM and the Dragon floppy disk drive together with Dragon DOS, whereby the Dragon DOS only serves to load the OS-9 floppy disk and is then switched off. With the help of OS-9 it was possible for the first time to run several programs simultaneously on the Dragon computers (" multitasking "). This enabled, for example, the control of a printer (“ spooling ” as a background process) and the input of new data into a word processing program (as a foreground process) at the same time. Together with the network capability ("multiuser") and the availability of almost 64 KB RAM, the efficiency increase in computer work was considerable. In addition, the screen display was expanded to include lower-case letters and various graphic characters, which was also a great advantage for user-friendliness. With this and an extensive program library, Dragon Data Ltd. To be able to open up further markets, especially in the professional business environment.
The third party provider Compusense Ltd. 1984 presented his Dragon adaptation of the FLEX operating system, which was developed in 1977 in the USA, which is in direct competition with OS-9 . The program package on diskette contains the diskette operating system, small auxiliary programs and drivers for various printers as well as a powerful macro assembler, which initially represented the real reason for many Dragon users to purchase FLEX. When it was released, a wealth of other programs, for example for joint operation of FLEX with the Extended BASIC of the Dragon computers, as well as word processors and database applications, was available. Due to the beginner's friendliness, the extensive documentation, the software architecture better adapted to the 6809 processor, the support of computer terminals via RS-232 interface and last but not least the extensive range of programs, Eurohard SA, as the successor to Dragon Data Ltd. immediately preferred FLEX as the new official operating system for Dragon computers and then discontinued its support for OS-9.
Programming languages and application programs
Based on the system software, the user-specific use of the Dragon computers in a wide variety of application areas was of great importance. Was the processing of a task with z. For example, programs that can be purchased are not possible for technical or economic reasons, or if, for example, new types of entertainment software are to be produced, this had to be done independently with the help of the appropriate programming languages.
Assembly language
In the early 1980s, the creation of time-critical action games and applications in control engineering required optimal use of the hardware, especially the main memory. In the home computer sector, this was only possible through the use of assembly language with appropriate translation programs, the assemblers . In many cases assemblers were delivered with an associated editor for entering the program instructions (“source code”), often also as a program package with debugger and disassembler for error analysis. In the professional development environment, cross assemblers were often used. This made it possible to generate executable programs for home computers on more powerful and easy-to-use third-party computer platforms. For example, the Dragon BIOS was developed on a PDP-11 computer from DEC .
The most popular 6809 assemblers for Dragon computers include Editor / Assembler (Dragon Data Ltd, 1983), Dream Assembler (Dragon Data Ltd, 1983, 1984 reissued as Alldream Assembler), Encoder09 (Premier Microsystems Ltd., 1983 , also available as an upgrade ROM module for the Delta DOS interface), DASM (Compusense Ltd., 1983, Inline-Assembler for use with Extended BASIC), MACE (Windrush Micro Systems Ltd., 1983, also delivery as a plug-in module combined EPROM - burner ) and the editor of assembler alligata software .
In many cases, programming beginners preferred the clear and easy-to-use, but less powerful, high-level programming languages.
Interpreter high-level languages
Extended Microsoft BASIC, which is delivered with the Dragon computers and is easy to learn, enables easy programming of even difficult problems thanks to its extremely powerful instruction set and the available 32 KB RAM. The fundamental limitations inherent in the nature of the interpreter, such as the low execution speed and the large amount of memory required, had a disadvantageous effect on usability. It is worth mentioning the incompatibility of the Extended Microsoft BASIC built into the Dragon with that of the Tandy Color Computer, which is otherwise largely software-compatible, so that BASIC program texts from both systems are not easily interchangeable.
The Extended Microsoft BASIC was accompanied by another, easy-to-learn interpreter language with the Dragon logo .
Compiler high-level languages
The middle ground between high-level interpreter language (slow to execute, but easy to read source codes and easy error analysis) and assembly language (difficult to learn and cumbersome to use, but at the beginning of the 1980s there was no alternative to generating faster and memory-efficient programs) also established themselves in the home computer sector the high-level compiler languages during the 1980s. The execution speed of the machine programs generated with it was much faster compared to interpreted programs such as the built-in Extended Microsoft BASIC, but did not quite come close to that achieved by assemblers. However, the speed disadvantages compared to assembled programs were often accepted in favor of an easier-to-maintain source code.
With the introduction of the Dragon 64 and the OS-9 and FLEX floppy operating systems, the user had a wide range of compiler languages such as Pascal , COBOL , Forth , Fortran and C available.
Applications
The range of programs for the Dragon computers included the programming languages for creating your own applications as well as a large selection of ready-made commercial application software. It covered a wide variety of topics such as word processing (including Editext, Telewriter, Rainbow Writer, Edit +, Stylograph), spreadsheets (including Dynacalc), database systems (including RMS) and image processing (Picture Writer). In addition, there was a large number of programs for copying data carriers, controlling peripherals or for use in very special areas such as process management in agriculture (FarmFax).
Games
By far the largest part of the both commercial and freely available Dragon software are the games. The most popular were primarily action games such as Chuckie Egg (1983, A&F Software), Donkey King (1983, Microdeal), and Jet Set Willy (1985, Software Projects) and Airball (1989, Microdeal).
In addition to Dragon Data Ltd., one of the best-known manufacturers of Dragon games was UK based Microdeal. Between 1982 and 1988 Microdeal alone brought around 200 different games of different quality onto the market, a large number of which are detailed imitations of well-known arcade models. To prevent foreseeable disputes with the rights holders, these titles were often offered under a name similar to the original: Donkey Kong became Donkey King (later changed to The King due to impending lawsuits ), Galaga became Galagon , Scramble became Skramble , etc. Further popularity Microdeal obtained through its mascot "Cuthbert", to whom a number of popular, but also often other bestsellers imitated platforming games are dedicated. The distribution of Cuthbert in the Jungle, for example, had to be forced to resemble Pitfall II! to be set on the operation of Activisions .
In addition to the countless publications in magazines, over one hundred different manufacturers contributed their share to the extensive range of games for the Dragon computers. Apart from the Dragon Data Ltd. With the plug-in module titles produced, commercial Dragon games were mostly delivered on compact cassettes with more or less effective copy protection mechanisms.
Magazines
In the 1980s, along with specialist books, computer magazines played an important role for many home computer owners. The editions, which were often published monthly, contained test reports on innovations, programming instructions and software for typing. They also served as an advertising and information platform as well as for establishing contact with like-minded people. The best-known magazines published in West Germany include Happy Computer , ASM - Current Software Market , Computer Kontakt , Computronic (Roeske-Verlag, later Tronic-Verlag) and Mein Home-Computer (Vogel-Verlag).
A variety of specially tailored publications have been available to Dragon users in the UK since 1983. Among the best known are the from 1983 by Dragon Data Ltd. Stop Press magazine and its successor Dragon World sent to registered Dragon owners . In May 1983 the independent and very popular Dragon User Magazine, published in large numbers by Sunshine Books, hit the kiosks; its publication was only discontinued in January 1989. From 1985 onwards, Spanish language magazines such as Dragon Software and Video Dragon were also available for some time . In addition to the kiosk magazines, a large number of other local club magazines ("fanzines") appeared in limited editions over the years.
emulation
After the end of the home computer era at the beginning of the 1990s and with the advent of powerful and affordable computing technology at the end of the 1990s, dedicated enthusiasts increasingly developed programs to emulate home computers and their peripherals. To play old classics from a wide variety of home computer systems, a single modern system with data images of the corresponding home computer programs is sufficient with the aid of the emulators. The emergence of the emulators continued, among other things. a. an increased transfer of otherwise possibly lost software to modern storage media, which makes an important contribution to the preservation of digital culture.
The most powerful emulator of the Dragon computers is XRoar, which is available for various computer and video console platforms. Due to the technical proximity of the Dragon devices to the models of the Tandy Color Computer, their emulation is also covered by XRoar. Other emulators are the DREaM, MESS, T3 and PCDragon II available for various systems.
reception
Contemporary
When the Dragon 32 appeared, the reviews of the trade press were largely positive. On the hardware side, particular emphasis was placed on the typewriter keyboard with space bar, which was more comfortable than its direct competitors Tandy Color Computer and Sinclair ZX Spectrum, and the 32 KB working memory, which was generous at the time. The powerful microprocessor, the Centronics interface installed ex works and the analog joystick ports were also able to convince the critics. On the software side, the built-in Extended Microsoft BASIC, with its large range of commands and extensive graphics options, was very popular in many cases. The positive overall impression was mainly clouded by the instructions that were classified as in need of revision, screen colors that were unfriendly to the eyes, limited text editor skills and the highest sales price in the competitive field. In spite of this, it was the Dragon 32 in the home computer segment that was often given the highest ratings and which was therefore often recommended to buy, especially for programming beginners and hobby users. This was justified not least by the better price-performance ratio compared to the direct competitors Tandy Color Computer and Sinclair ZX Spectrum as well as the good marketing on the part of Dragon Data, which was able to avoid delivery bottlenecks, such as those that occurred with the Commodore VC 20 or Sinclair ZX Spectrum .
The Dragon 64, on the other hand, was met with somewhat less approval, especially since the field of competition had already grown when it was launched and had also gained in quality with the Commodore 64. In addition to minor software incompatibilities with the previous model, the overall concept as a mere extended Dragon 32 was mainly the subject of criticism, although the computer was classified as contemporary and competitive. In addition to the low price, the reason for this was seen as the revised BASIC, resolved keyboard problems, various hardware extensions (e.g. RS-232 interface) and, above all, the OS-9 operating system, which enables the computer to be used in a business environment and for Unix - Beginners, but less interesting for home users.
Despite the decline that began in 1985, the Dragon computers enjoyed great popularity as an inexpensive entry-level model in Europe due to their robust workmanship, the large housing well suited for modifications and not least because of the easy portability of the programs of the Tandy Color Computer, with sales figures overall in 1985 especially in Germany clearly behind those of the market leader Commodore 64 (approx. 60 percent market share) and Atari 800XL as well as Sinclair ZX Spectrum.
Retrospective
The Dragon 32 and Dragon 64 are meanwhile experiencing increased awareness on the Internet, in magazines and books. Most of the time, the Dragon 32 is classified as a clone of the Tandy Color Computer, which its equally powerful and exotic 6809 system architecture, due to a lack of software support in Europe, should also be undone. More differentiated characterizations in the context of the competitive situation in 1982 range from “excellent all-purpose device for a wide variety of user groups” to “most powerful device in its price range” to terms such as “device with revolutionary design”.
In addition to the software supply, which is viewed as sparse compared to other systems, the checkered history of the manufacturer Dragon Data Ltd. There has been speculation about the cause of the rapid disappearance of the Dragon computers from the home computer market. The market dominance achieved within a short period of time in the highly competitive home computer market in Great Britain was already a thing of the past a year later. This transition to a niche existence is largely attributed to economic misjudgments and decisions by the changing management of Dragon Data Ltd. by many authors. returned. In particular, the underestimation of the fast pace of the home computer market and the associated short product cycles led to massive and lossy overproduction in 1983 in the age of rapidly obsolete hardware. New and requested extensions were only hesitantly or not at all brought to market readiness. An attractive and user-appealing successor model for the Dragon 32 could not be realized, instead a simply upgraded Dragon 32 in the form of the Dragon 64 appeared. In addition, there are technical and commercial errors in sales practice, which never addressed the considerable differences between pre-ordered and actually purchased goods on the part of the major distributors and thus also resulted in overproduction and thus losses. If at least the errors leading to massive overproduction had been recognized and eliminated early, the company Dragon Data Ltd. according to economist David Clutterbuck can be saved. From time to time, general developments in the home computer industry, such as the video game crash from the end of 1983 in the USA and its strong effects on Europe as well, influence the deliberations on the disappearance of Dragon computers from the home computer market.
literature
- Duncan Smeed, Ian Sommerville: Inside the Dragon. Addison-Wesley, 1983, ISBN 0-201-14523-5
- Jörn W. Janneck, Till Mossakowski: The Dragon 32/64 Lexicon. Röckrath microcomputer, Aachen 1984, ISBN 3-925074-05-8 .
- U. Schollwöck: Machine language on the Dragon 32/64. IWT-Verlag, Munich 1984, ISBN 3-88322-105-8 .
Web links
- Dragon User Magazine Collection All 69 issues as searchable PDF documents.
- The Dragon Archive Extensive archive and documentation (English).
- Dragonwiki.com Extensive archive and documentation (English).
- Instructions for the Dragon-BASIC (English).
- Supplementary documents for Dragon 64 (English).
- Developer website for the emulator XRoar with extensive information archive and the possibility of downloading.
Remarks
- ↑ a b c d e f g h i David Linsley: A Slayed Beast - History of the Dragon computer. (1. The conception, the formative months and the birth) Binary Dinosaurs, accessed December 25, 2013.
- ↑ Ruth Bosch: My first weeks with the Dragon 32nd PM computer booklet. Issue 4, 1983, p. 62.
- ↑ MC guidacomputer. MC Microcomputer, January 1984, p. 90.
- ↑ MC guidacomputer. MC Microcomputer, March 1984, p. 134.
- ↑ a b Dragon now even more attractive. PM computer notebook. Issue 5, 1984, p. 16.
- ^ How they compare. In: byte . Volume 8, No. 1, p. 49 ( ( Page no longer available , search in web archives: archive.org )).
- ↑ a b News on the personal computer market. PM computer notebook. Issue 1, 1983, p. 49.
- ↑ MC guidacomputer. MC Microcomputer, January 1984, p. 90.
- ↑ a b Dragon User Magazine. September 1983, p. 19.
- ↑ MC guidacomputer. MC Microcomputer, March 1984, p. 134.
- ↑ Dragon 64 runs under OS-9. Computer week. May 18, 1984.
- ↑ La puissance. Led Micro Magazine. Issue 10, 1984.
- ↑ 1984 absorbed into Rexnord Corporation.
- ↑ In the computer systems of that time with pixel graphics, the calculations for drawing and moving geometric objects such as lines, circles or filled areas in the video memory were the task of the CPU (keywords: Bresenham algorithm and software bit blitting ). Specialized graphics modules, which led to a noticeable reduction in the load on the CPU, were only introduced from the mid-1980s. B. in the Commodore Amiga with its " Amiga Blitter " used.
- ^ The number of the beast. Popular Computing Weekly. November 18, 1982, p. 10 f.
- ↑ a b c d computer course. Issue 54, p. 1508.
- ↑ a b Winnie Forster: Game consoles and home computers. 3rd edition, Gameplan, Utting 2009, ISBN 978-3-00-024658-6 , p. 212.
- ^ Street Life - Breathing Fire into the Mettoy Dragon. Popular Computing Weekly. August 5, 1982, p. 11.
- ↑ a b c d e Tony Smith: The Dragon 32 is 30. The Register, August 1, 2012. Retrieved December 26, 2013.
- ↑ a b Dragon grows on Prutech diet. Popular Computing Weekly. November 11, 1982, p. 10.
- ^ A b Gordon Laing: Digital Retro: The Evolution and Design of the Personal Computer. Ilex, Lewes 2004, ISBN 978-1-904705-39-0 , p. 106.
- ↑ Editorial. Popular Computing Weekly. November 4, 1982, p. 3.
- ^ The end of the road for Dragon Popular Computing Weekly. 7-13 June 1984, p. 3.
- ↑ Taneli Lukka: Dragon 32: Finlux version. Old-computers.com, accessed January 16, 2014.
- ↑ A subsidiary of Prudential plc .
- ↑ David Linsley: A Slayed Beast - History of the Dragon computer. (2. The adoption part 1 and the early growth - the Tony Clarke year) Binary Dinosaurs, accessed December 25, 2013.
- ↑ Dragon goes across the pond! Popular Computing Weekly. May 26 - June 1, 1983, p. 1.
- ↑ a b Dragon User Magazine. December 1983, p. 22.
- ↑ Tony Smith: MEGAGRAPH: 1983's UK home computer chart toppers The Register, January 3, 2013. Retrieved December 29, 2013.
- ↑ Dragon crash averted by the man from Prutech. Popular Computing Weekly. 8-14 September 1983, p. 1.
- ↑ Marketed there as Dragon by Tano Color Computer .
- ↑ Dragon User Magazine. November 1983, p. 7.
- ↑ a b Dragon upgraded to 64 Popular Computing Weekly. 8-14 December 1983, p. 5.
- ^ Dragon News. Happy computer. June, 1984, p. 8.
- ↑ David Linsley: A Slayed Beast - History of the Dragon computer. (4. More Products hit the shops as GEC wind the screw.) Binary Dinosaurs, accessed January 1, 2014.
- ↑ Large remnants of the bankruptcy estate were sold to an unknown major investor by December 1984.
- ↑ GEC breathes new fire into Dragon Popular Computing Weekly. 16.-22. February 1984, p. 1.
- ^ Home Computer Weekly. May 15, 1984, p. 7.
- ↑ Advertisement. Computer contact magazine. Issue 4, 1985, p. 39.
- ↑ Computer, computer. C't. Volume 5, 1984, p. 14.
- ↑ Dragon 64 with OS-9 operating system. C't. Volume 6, 1984, p. 12.
- ↑ GEC breathes new fire into Dragon Popular Computing Weekly. 16.-22. February 1984, p. 5.
- ^ A b David Linsley: A Slayed Beast - History of the Dragon computer. In: Binary Dinosaurs - Dragon History. binarydinosaurs.co.uk, accessed December 25, 2013 (3. The adoption part 2 - GEC take charge as Clarke is ousted).
- ^ The end of the road for Dragon Popular Computing Weekly. 7-13 June 1984, p. 1.
- ↑ a b Personal Computer News. June 16, 1984, p. 4.
- ↑ a b Dragon User Magazine. October 1984, p. 8.
- ↑ Dragon User Magazine. January 1985, p. 19.
- ^ Dragon moves to Spain Popular Computing Weekly. 19.-25. July 1984, p. 5.
- ↑ Eurohard - plans ahead. Dragon User Magazine. September 1985, p. 7.
- ^ Gordon Ross: Hecho en España. Dragon User Magazine. January 1985, p. 20.
- ↑ Dragon User Magazine. April 1985, p. 7.
- ↑ a b Dragon User Magazine. December 1987, p. 3.
- ↑ a b Jörn W. Janneck, Till Mossakowski: Das Dragon 32/64 Lexikon. 1984, pp. 8-18.
- ↑ a b U. Schollwöck: Machine language on the Dragon 32/64. 1984, p. 169 ff.
-
↑ The BASIC command for this is
EXEC 48000. - ↑ Duncan Smeed, Ian Sommerville: Inside the Dragon. 1983, p. 333 f.
- ↑ Jörn W. Janneck, Till Mossakowski: Das Dragon 32/64 Lexikon. 1984, pp. 19-22.
- ↑ a b c d Retro Gamer Magazine. Issue 37, p. 21.
- ↑ Jörn W. Janneck, Till Mossakowski: Das Dragon 32/64 Lexikon. 1984, pp. 30-36.
- ↑ Jörn W. Janneck, Till Mossakowski: Das Dragon 32/64 Lexikon. 1984, pp. 19-36.
- ↑ Jörn W. Janneck, Till Mossakowski: Das Dragon 32/64 Lexikon. 1984, p. 246 f.
- ↑ Dietmar Eirich: Computer Periphery. Heyne, Munich 1985, ISBN 3-453-47058-3 , p. 51 ff.
- ↑ Dragon User Magazine. September 1985, p. 19.
- ↑ Dragon User Magazine. May 1984, p. 9.
- ↑ Dragon User Magazine. September 1984, p. 27.
- ^ Dragon discs Popular Computing Weekly. 17.-23. February 1983, p. 1 and p. 5.
- ↑ A claim to fame Popular Computing Weekly. 25.-31. August 1983, p. 13.
- ↑ Justin Johnson, Keith Davis: Using Floppy Disks with the Dragon Microcomputer. , Premier Microsystems Ltd. and Cumana Ltd., 1983, ISBN 0-9508762-2-4 , p. 5.
- ↑ Dragon User Magazine. May 1983, p. 24.
- ^ Moving up with OS 9. Dragon User Magazine. April 1984, p. 31.
- ↑ Mike Gerrand: Taking the tablets. Dragon User Magazine. February 1986, p. 12.
- ^ Trojan lets out light. Dragon User Magazine. May 1983, p. 7.
- ↑ Dragon User Magazine. October 1983, p. 15.
- ↑ Dragon User Magazine. October 1983, p. 5 and p. 42.
- ^ Roy Cotes: Dragon Plus. Dragon User Magazine. January 1986, p. 9.
- ↑ Dragon User Magazine. January 1986, p. 9 f.
- ^ Roy Coates: The Dragon's Claw. Dragon User Magazine. December 1985, p. 42.
- ↑ a b Dragon Quest. Popular Computing Weekly. December 2, 1982, p. 12.
- ↑ Dragon User Magazine. May 1983, p. 23.
- ↑ a b c Dragon Data software push. Dragon User Magazine. January 1984, p. 8.
- ^ Mike Harrison: Dragon library. Dragon User Magazine. June 1984, pp. 36-44.
- ↑ Dietmar Eirich: Computer for reference. Compact Verlag, 1989, ISBN 3-8174-3564-9 , p. 212.
- ↑ Brian Cadge: firmware. Dragon User Magazine. September 1985, p. 19.
- ↑ Delta DOS requires around 1.8 KB of RAM to operate.
- ↑ Duncan Smeed, Ian Sommerville: Inside the Dragon. 1983, p. 351 f.
- ↑ Justin Johnson, Keith Davis: Using Floppy Disks with the Dragon Microcomputer. , Premier Microsystems Ltd. and Cumana Ltd., 1983, ISBN 0-9508762-2-4 , p. 10.
- ^ Dragon World. No. 2, February 1984, p. 19.
- ↑ Dragon User Magazine. November 1983, p. 21 ff.
- ↑ Computer course. Issue 56, p. 1554.
- ↑ Dragon User Magazine. April 1984, p. 31 ff.
- ↑ Dragon User Magazine. February 1985, p. 23 ff.
- ↑ Dragon User Magazine. September 1985, p. 15 f.
- ↑ a b U. Schollwöck: Machine language on the Dragon 32/64. 1984, p. 6.
- ↑ Dragon User Magazine. September 1985, p. 22.
- ↑ To easy life for some. Popular Computing Weekly. 15-21 December, p. 32.
- ↑ Dragon User Magazine. May 1983, p. 7.
- ↑ Dragon User Magazine. September 1983, p. 17.
- ↑ U. Schollwöck: Machine language on the Dragon 32/64. 1984, p. 1.
- ↑ Dragon User Magazine. June 1983, p. 37.
- ^ A b F. G. Swygert: Tandy's Little Wonder The Color Computer 1979-1991. 2nd edition, FARNA Systems, February 2006, p. 36.
- ↑ Helmut Kraus: Microcomputer Lexicon. Sybex-Verlag, 1988, ISBN 3-88745-518-5 , p. 44.
- ↑ U. Schollwöck: Machine language on the Dragon 32/64. 1984, p. 5 f.
- ↑ Versatile software. Dragon User Magazine. January 1985, p. 9.
- ↑ Dragon User Magazine. June 1983, p. 9.
- ^ Winnie Forster: Computer and video game maker. Gameplan, Utting 2008, ISBN 978-3-00-021584-1 , p. 206.
- ↑ Happy Computer - Behind the Scenes. ( Memento from February 20, 2015 in the Internet Archive ) Videospielgeschichten.de, accessed on January 28, 2015.
- ↑ David Linsley: A Slayed Beast - History of the Dragon computer. In: Binary Dinosaurs - Dragon History. binarydinosaurs.co.uk, accessed December 25, 2013 (2. The adoption pt I and the early growth - the Tony Clarke year, 7. Eurohard goes quiet as the beast dies a slow death).
- ↑ World of Dragon Archive: Magazines. and Fanzines Worldofdragon.org, accessed January 28, 2015.
- ↑ Andreas Lange: What archives, museums and libraries can learn from gamers - and vice versa. Retrieved February 23, 2014.
- ↑ Tips and tricks for the Dragon-32. Happy computer. December 1983, p. 43 ff.
- ↑ a b Dietmar Eirich: Everything about computers: What the microcomputer can do for me. Heyne, Munich 1984, ISBN 3-453-47038-9 , p. 102.
- ↑ a b Telematch Computer. August 1984, p. 29.
- ↑ a b chip . March 1983, p. 64 ff.
- ↑ a b computer course. Issue 56, p. 1555.
- ^ The last word Popular Computing Weekly. July 28 - August 3, 1983, p. 7.
- ↑ a b A Dragon for your Dungeon. Your computer. August 1982, pp. 20–22, here p. 22.
- ↑ Chip, March 1983, p. 66.
- ↑ The Dragon 32nd byte. Vol. 8, No. 1, p. 46.
- ^ Dragon 64 Review. Your computer. January 1984, p. 70 f.
- ↑ Dragon 64: A house dragon for cheerful and serious hours. Happy computer. July 1984, pp. 170-173, here p. 173.
- ↑ Dietmar Eirich, Peter Herzberg: Computer Yearbook '85. Heyne, Munich 1984, ISBN 3-453-47042-7 , p. 29.
- ↑ a b c d Classic Videogames Hardware Genius Guide, Imagine Publishing Ltd., 2011, ISBN 978-1-908222-22-0 , chapter 7.
- ^ David Clutterbuck, Sue Kernaghan: The Phoenix Factor. Weidenfeld & Nicolson, 1990, ISBN 0-297-81123-1 , p. 110.
- ^ David Clutterbuck, Sue Kernaghan: The Phoenix Factor. Weidenfeld & Nicolson, 1990, ISBN 0-297-81123-1 , p. 109 ff.
- ↑ Boisy G. Pitre, Bill Loguidice: CoCo: The Colorful History of Tandy's Underdog Computer. CRC Press, 2014, ISBN 978-1-4665-9247-6 , p. 86.
