Texas Instruments TI-99/4

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Texas Instruments TI-99/4
TI99-4 front.jpg
logo
Manufacturer
United StatesUnited States Texas Instruments
Type Home computers
publication United StatesUnited States1979 (June) 1980
GermanyGermany
End of production United NationsU.N.1981 (June)
Factory price United StatesUnited StatesUS $ 1,150 (including monitor) DM 2,700 (including monitor)
GermanyGermany
processor TMS9900
random access memory 16 KB RAM (8-bit; max. 48 KB)
256 bytes SRAM (16-bit CPU RAM)
graphic TMS9918 ( NTSC )
  • Max. 256 × 196 pixels
  • Max. 40 × 24 characters
  • Max. 15 colors
  • Max. 32 sprites
Sound TMS9919
Disk Cartridges
Audio cassettes
5¼-inch floppy disks (SS, SD)
operating system TI BASIC
Graphics Programming Language
predecessor -
successor TI-99 / 4A

When Texas Instruments TI-99/4 (short TI-99/4 ) is a home computer of the US technology group and the late 1970s, the world's leading semiconductor manufacturer Texas Instruments (TI). The computer, which was equipped with a 16-bit main processor that was very powerful for the time, 16 kilobytes of working memory (RAM), 31 kilobytes of permanent memory (ROM) and special components for image and sound output, was first presented in June 1979 at the Summer Consumer Electronics Show in Chicago presented to the world public.

The TI-99/4 was only available on the North American market from the beginning of 1980 due to manufacturing problems and radio interference suppression . In Europe, the computer was only ready for the market in the second half of 1980 and was initially only available in an NTSC version that was unsuitable for the PAL television sets customary there . A PAL-compatible version was later offered in Europe. Due to the late market launch of the PAL version of the TI-99/4, the successor model TI-99 / 4A has achieved a considerably higher level of awareness and distribution than the TI-99/4.

The technical history relevance of the TI-99/4 lies in the fact that it is the first 16-bit home computer designed for private users. However, due to the high price and some technical deficits, the computer sold only slowly. A total of approximately 20,000 units of Texas Instruments' first home computer were sold. In the summer of 1981 the TI-99/4 was replaced by a technically modified, more powerful version with the model designation TI-99 / 4A .

Differences to the successor model TI-99 / 4A

The main differences between the TI-99/4 and its successor TI-99 / 4A were as follows:

  • The TI-99 / 4A had the larger and significantly better keyboard, which on the TI-99/4 was practically just buttons like those found on a pocket calculator. Due to the smaller number of keys and the lack of a distinction between uppercase and lowercase letters, some control functions on the TI-99/4 were not operated in combination with the Ctrl key, but in combination with the Shift key . This required a high level of discipline from people who were used to using the shift key to write capital letters, because a wrong key action could have serious consequences (examples: ⇧- Ccaused a program to abort , ⇧- Qa restart of the computer).
  • The copyright notice on the splash screen of the TI-99/4 marked 1979, while the TI-99 / 4A stated 1981.
  • In addition to TI BASIC , a program for calculating algebraic expressions called "Equation Calculator" was integrated in the TI-99/4. This explains why the TI-99/4 needed a 5 Kbyte larger ROM .
  • While the TMS9918 graphics processor was installed in the TI-99/4 , the TMS9918A was used in the TI-99 / 4A, which had an additional display mode.
  • The TI-99/4 could only accept and display uppercase letters, the TI-99 / 4A also lowercase letters.
  • In contrast to the TI-99 / 4A, the TI-99/4 was equipped with a headphone jack and / or loudspeaker. Where earlier versions of the TI-99 / 4A had the elongated aluminum label with the imprint "Solid State Software", the slide control for the volume setting was on the TI-99/4. The circuit board with the necessary amplifier was located under the shaft cover.
  • The shape of the power supply unit of the TI-99/4 was significantly larger than that of the TI-99 / 4A, as it also contained the circuit board with rectifier and voltage regulator in addition to the transformer. In the case of the TI-99 / 4A, this board was located under the cover of the module bay and thus replaced the board of the amplifier from the TI-99/4.
  • Since the power supply of the TI-99 / 4A supplied unregulated alternating current, whereas that of the TI-99/4 supplied regulated direct current, the connector was also modified to protect it. It still fit mechanically, but only made electrical contact with the TI-99 / 4A.
  • The module bay on the TI-99/4 was designed differently than on the TI-99 / 4A.

Otherwise, the TI-99/4 and TI-99 / 4A were largely identical in structure, so that further details on the TI-99/4 can be found in the article on the TI-99 / 4A .

Peripherals

A TI-99/4 with all peripheral devices that were available in the form of sidecars (from left: speech synthesizer , dot matrix printer, memory expansion, RS-232 interface, drive controller, 5¼-inch floppy disk drive and modem)
A model of the TI-99/4 made for the European market with loudspeaker and volume control
Close up of speaker and volume control (right side)

Texas Instruments itself produced a whole range of peripheral devices from 1980, which were intended for the TI-99/4, but can also be connected to the successor model. These so-called sidecars have their own external power supply unit to prevent heat build-up inside the housing and overloading of the computer's power supply. Exceptions are the modem for exchanging data with other computer systems and the solid state speech synthesizer . In addition, all peripheral devices of the first generation have a looped-through circuit board connector, so that up to six sidecars can be connected to the console at the same time in a daisy-chain process.

The following list provides an overview of the peripheral devices offered by Texas Instruments, the design of which has been adapted to the external appearance of the TI-99/4:

  • PHP1100 Wire Remote Control (dual joysticks)
  • PHP1100 Joystick Controller (dual joysticks with a different design than the Wire Remote Controls )
  • PHP1500 Solid State Speech Synthesizer (extension module for artificial speech output)
  • PHP1600 Telephone Coupler (Modem)
  • PHP1700 RS-232 Interface Sidecar ( printer interface )
  • PHP1800 Disk Drive Controller Sidecar (control unit of the floppy disk drive)
  • PHP1850 Disk Memory Drive (5¼ inch floppy disk drive)
  • PHP1900 Solid State Thermal Printer ( Thermal Printer )
  • PHA2100 RF Modulator ( RF Modulator )
  • PHP2200 32 Kilobyte Memory Expansion Sidecar (32 KB RAM memory expansion)
  • PHP2300 Video Controller (control unit for an external video recorder )
  • PHP2400 P-Code Peripheral (Pascal interpreter)
  • PHP2500 80x4 Impact Printer ( matrix printer )
  • PHP2700 Program recorder (VCR program)
  • PHA4100 10 "Color Monitor (10-inch color monitor)

5¼ inch PHP1850 floppy disk drive

The PHP1850 is housed in a rectangular housing made of black plastic, which is equipped at the rear with a connection for the connection cable and ventilation slots for cooling the electronics. The drive has a snap lock on the front to fix the inserted floppy disks. It uses the FD1771 floppy disk controller from Western Digital and has a magnetic read / write head with an average access time of 463 ms. The drive uses standard 5¼-inch floppy disks with a maximum of 40 tracks. It allows a data volume of up to 89 KB to be stored on one disk side in single density with variable sector size.

The PHP1850 can only be operated in connection with a control unit of the type PHP1800, which on the one hand regulates the positioning of the read / write head and on the other hand manages the table of contents of the diskette. The Disk Manager plug-in module, on which the TI-DOS floppy operating system is located, is also required.

The original price of the PHP1850 was US $ 499.95 in 1982, while the PHP1800 Disk Drive Controller, in addition to the included Disk Manager plug-in module, had to pay a further US $ 299.95.

Individual evidence

  1. ↑ Personal Computer Products , ed. Texas Instruments Houston (1982), unpag.
  2. ↑ TI Home Computer Accessory: Disk Memory Drive Model PHP1850 , ed. Texas Instrumens, Dallas (1980), p. 4.
  3. ↑ a b c "TI-99 / 4A: the home computer that can do a lot", ed. Texas Instruments, In: Computer Personal , Vol. 2, No. 15 (1983), unpag.
  4. ↑ TI Home Computer Accessory: Disk Memory Drive Model PHP1850 , ed. Texas Instrumens, Dallas (1980), p. 1.
  5. ↑ TI-99 / 4A Home Computer Products. Suggested Retail Price List June-December, 1982 , ed. Texas Instruments, Dallas (1982), unpag.

Web links

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