aMIC (computer)

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AMIC (computer)
image
Manufacturer Polytechnic University of Bucharest (A. Petrescu, F. Iacob) / Fabrica de Memorii, Timișoara
Type Home computers
publication 1982
End of production 1984
Factory price ?
processor Z80 (2.5 MHz) (or 8080 , only experimental)
random access memory 16–48 kb (4116 dynamic logic circuits)
graphic 8 kb graphics memory with 256 × 256 px, black and white
Sound integrated speakers in the keyboard
Disk Datasette , floppy disk drive
operating system BASIC with additional programs such as Monitoare V0.1, V0.2 (German: Monitore), MATE, Z80-V0.0, DEST (a kind of operating system), BASIC Interpreter and AsaMBlor
predecessor -
successor -

aMIC is a Romanian home and microcomputer that was produced and developed in the Polytechnic University of Bucharest (IPB) , Department of Computer Science, as a laboratory model by Adrian Petrescu and Francisc Iacob , and from 1983 to 1984 at the Fabrica de Memorii in Timișoara in Series was produced.

Between 1982 and 1983, the team at the IPB Institute for Computer Science experimented on several variants of this microcomputer using the 8080 and Z80 processors with the associated circuits.

The aMIC microcomputer came from the category of personal computers (home computers) with the aim of supporting a wide range of applications, as it had, for the time, high performance in relation to the low cost. Since many copies of the aMIC computer were produced, it could be used in many areas such as research, education and industry.

In the technological design of the prototype, great care was taken to use integrated circuits that were produced in Romania . As peripheral devices, aMIC was equipped with devices from the consumer goods sector: black and white televisions and cassette recorders. The hardware and software were designed as an open system. This approach allowed the coupling of peripheral devices in order to increase the performance and to enable the expansion of the areas of application: printer (model MIM40 Electromureş), modem, XY recorder (plotter), coupler method (programmable parallel and serial interfaces), etc. The aim of the software developments was to expand and improve monitors, assemblers , interpreters and compilers of a high-level programming language from existing computing systems.

hardware

The aMIC system was based on a bus that linked rows of data, addresses, commands and supplies. These rows were led to the outside through a 50-pin connector, which enabled the coupling of extended peripheral devices with direct memory access (example: floppy disk ) or non-standardized peripheral devices. The data bus established the connection between the central unit, the EPROM / RAM memory, the programmable parallel interface, the programmable serial interface (with an 8251 circuit, for transmission speeds of 300/600 or 1200 baud) and the television interface. There were also two additional peripheral connections with 25 contacts each.

processor

The central unit was based on the Z80 microprocessor , which operated at a frequency of 2.5  MHz . The Intel 8080 processor was only used experimentally in the laboratory.

Storage

The EPROM memory, which - depending on the version - contained the monitor and the BASIC interpreter or just the monitor, the assembler and the text editor , had a capacity of 16 kb and is based on the principle of the 2716 circuit. The RAM memory, which was used for user applications, consisted of dynamic circuits based on the 4116 circuit and offered a maximum capacity of 48 kb, of which 8 kb was available for the graphics memory.

Periphery

The optional programmable parallel interface was implemented using the 8255 circuit. It was used for coupling devices from the standard equipment, but also for other non-standardized devices. These include analog-to-digital and digital-to-analog converters , joysticks , printers, various contacts, LEDs, etc. In addition, there was another 8255 circuit that was responsible for communication between the keyboard, loudspeakers and cassette recorder .

The programmable serial interface was optional and was made possible with an 8251 circuit. This interface was used for communication with devices that support serial data transmission: display terminal , modem , TTY and possibly another computer that also had a serial interface.

The interface connection to the television set (via a coaxial cable) generated the complex video signal, which was modulated from the graphics memory content (8 kb).

The keyboard was slim and flexible and had 59 keys, with the alphanumeric keys in QWERTY format. It also had an integrated loudspeaker. The keyboard also had 16 semi-graphic characters that could be displayed normally or inverted, just like the alphanumeric characters. Switching between video normal and video inverted was done with the key combination CTRL + E. With the special RESET key, the system returned to the initial state and the display to normal video mode. The INT key enabled some interrupts to be triggered via the keyboard, which could then be intercepted and handled by special programs.

display

The alphanumeric, semi-graphic and graphic information was displayed using a normal black and white television. A resolution of 256 × 256 pixels was available for graphic reproduction . The alphanumeric characters could be mapped on 32 lines, 30 characters per line. The preprogrammed character generator allowed the representation of 64 characters from the ASCII standard and the semi-graphic characters mentioned above. The character set could also be changed and adapted as required.

The connection to the television set was via the antenna connection with a coaxial cable, with the modulator set to Band III VHF , channels 6-12.

software

aMIC - full configuration

The storage of the programs in machine code, assembler or BASIC was carried out on normal magnetic tapes (audio cassettes) using commercial cassette recorders . The transmission speed of the information was around 1600 bauds (this corresponds to 1.6 Kbps in this case ). This enabled a relatively short readout and write time for the programs, compared to the Romanian computers of the time. The basic software contained: monitors, an assembler and a BASIC interpreter. In contrast to other computer systems from this category, where the user worked with a 'BASIC machine', the aMIC microsystem offered a monitor program that was persisted in the EPROM. This carried out the interpretation and execution of the commands entered through the keyboard. The monitor consisted of a collection of routines that could be invoked from the keyboard as well as through the programs created by the user. The execution of the monitor started immediately when the system was switched on (after the voltage supply was applied) or during operation by pressing the RESET button.

Several versions of the aMIC monitor were designed that offered different functions. The small version V0.1 used 2 kb of memory and had the following commands:

  • D - output of the content of a memory area;
  • F - loading a constant into a memory area;
  • M - moving the contents of a memory area to another memory area;
  • C - modification of internal registers;
  • X - display of internal registers;
  • S - display and change the contents of some memory locations;
  • G - execution of a program residing in memory;
  • K - storage of a file in internal memory on magnetic tape;
  • L - loading a file from the magnetic tape into the internal memory;
  • B - Running the BASIC interpreter.

The commands listed above took care of loading the programs into object code, correcting them and executing them. In this way, all computer resources could be effectively controlled so that complex, high performance applications could be debugged / examined and executed.

In addition, the applications Monitoare V02 (2.5 kb memory), MATE (6 kb memory), Z80-V0.0 and DEST offered a number of other functions with regard to assembling and debugging programs that were written in assembly language.

The interpreter for the BASIC language was designed in several versions with regard to the implemented instruction sets. The final version includes, in addition to the standard BASIC instruction sets and the instruction sets for manipulating the matrices , graphic processing and the CALL operation.

The FORTH system - which was used on the so-called aMIC-FORTH computers - was less frequent, but just as interesting, comprehensive and well implemented.

literature

  • A. Petrescu, F. Iacob, Gh. Rizescu, C. Novăcescu, E. Decsov, T. Ilin, F. Bar, R. Berindeanu, D. Pănescu: Totul despre… Calculatorul personal aMIC. Vol. 1 , Editura Tehnică Bucureşti, 1985.
  • A. Petrescu, F. Iacob, Gh. Rizescu, C. Novăcescu, E. Decsov, T. Ilin, F. Bar, R. Berindeanu, D. Pănescu, C. Constantinescu, I. Petrescu, A. Matekovits: Totul despre … Calculatorul personal aMIC . Vol. 2. Editura Tehnică Bucureşti, 1985.

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