TI-99/4A
Manufacturer | Texas Instruments |
---|---|
Release date | October 1979 |
Introductory price | US$1,150 (equivalent to $4,830 in 2023) |
Discontinued | 1981 |
Units shipped | ~20,000 |
CPU | TMS9900 @ 3 MHz |
Graphics | TMS9918 |
Successor | TI-99/4A |
SN94624 | |
Predecessor | TI-99/4 |
---|
The TI-99/4 and TI-99/4A are
Based on Texas Instruments's own
The calculator-style keyboard of the TI-99/4 was cited as a weak point, and TI's reliance on
The 1981 US launch of the TI-99/4A followed Commodore's VIC-20 by several months. Commodore CEO Jack Tramiel did not like TI's predatory pricing in the mid-1970s and retaliated with a price war by repeatedly lowering the price of the VIC-20 and forcing TI to do the same. By late 1982, TI was shipping 5,000 computers a day from their factory in Lubbock, Texas.[3] By 1983, the 99/4A was selling at a loss for under US$100. Even with the increased user base created by the heavy discounts, Texas Instruments lost US$330 million in the third quarter of 1983[5] and announced the discontinuation of the TI-99/4A in October 1983. Production ended in March 1984.[3]
The TI-99/4 was intended to fit in the middle of a planned range of TI-99 computers, none of which were released, but prototypes and documentation have been found after the TI-99/4A was discontinued.[citation needed]
Features
The TI-99/4A is a self-contained console with the motherboard, ROM cartridge slot, and full-travel keyboard in the same case. The power supply is external. An RF modulator allows the use of a television as a monitor. Lowercase letters are displayed as small caps, rather than separate glyphs. TI BASIC, an ANSI-compliant BASIC interpreter based on Dartmouth BASIC, is built-in and includes support for graphics, sound, and file system access. Later versions of the 99/4A, identified by (C)1983 TEXAS INSTRUMENTS V2.2
on the title page, prevent the use of unlicensed ROM cartridges from third-party manufacturers such as Atarisoft.
Peripherals include a 5¼"
16-bit processor
Both TI-99/4 models use the
In order to build a complete 16-bit system, TI would have had to redesign many of their existing 8-bit support chips. Instead, TI decided to use existing devices for the majority of the system. The result was that only a small portion of the system was 16-bit, and used a second 8-bit
One of the key features of the TMS9900 from the minicomputer design that spawned it was the inclusion of several sets of
The new design put 256 bytes of random-access memory (RAM) on the 16-bit bus to store up to eight sets of registers. This area of RAM is known as the "scratchpad memory". As the processor's instructions are all 16-bit as well, the 8 KB internal system read-only memory (ROM) was also on the 16-bit side.[8] Only the program counter, status register, and workspace pointer registers are actually implemented on the chip itself.[8]
Included on the 8-bit side of the system is the majority of the RAM and almost all of the support chips, especially the video display controller (VDP). All accesses to the VDP system are executed eight bits at a time.[9] The system's RAM is managed by the VDP, which provides access to the CPU only when the VDP is not using the memory. This means that user programs and data has to be read over two machine cycles, essentially reducing speed by half. According to TI's former manager for microprocessors, who oversaw TMS9900 development, this negates the performance advantage of a 16-bit processor.[7]
Video display processor
Graphics in the 99/4A are generated by a
The TMS9918A supports character-based and bitmap display modes as well as hardware sprites. There are 32 single-color sprites total, but only a maximum of 4 can be displayed per scan line. Each sprite is either 8×8 or 16×16 pixels and can be scaled 2× to 16×16 or 32×32.
16 KB of RAM is provided for the Video Display Processor. VDP RAM is the largest block of writeable memory in the unexpanded TI-99/4A architecture, and is used for storing disk I/O buffers and TI BASIC user programs. Access to this memory has to use the VDP as an intermediary.
Expansion
TI-99 peripherals contain device drivers in ROMs in the hardware. When a new peripheral is attached, it is immediately available for any software that wants to use it. All device access uses a generic file-based I/O mechanism, allowing new devices to be added without updating software. The Peripheral Expansion System can hold two RS-232 cards, for a total of four RS-232 ports and two parallel printer ports.
The computer supports two cassette drives through a dedicated port, using a
Two digital
TI sold an official 32 KB RAM expansion.
Peripheral Expansion Box
The TI-99/4A can be upgraded via expansion cards added to an eight-slot, external chassis containing its own linear power supply and a full-height 5¼" floppy bay.
The PEB carries an analog sound input on the expansion bus, allowing the Speech Synthesizer's audio to be carried through the console to the monitor. The audio is also carried through the ribbon cable to the PEB, both allowing the relocation of the Speech Synthesizer to the PEB and the possibility of audio cards offering more features than the console's built-in sound. No official cards from TI do this.
Official cards from TI that were released and could be placed inside the PEB include
- 32 KB RAM expansion card
- RS-232 and parallel port card
- P-code card, implementing the UCSD p-system IV.0 by acting as a ROM-disk
- Diskette drive control card. The design allowed controlling both drives internally in the PEB and external drives.
Peripherals designed to be used without the PEB existed too.
Speech synthesizer
In the late 1970s and early 1980s, TI was a pioneer in speech synthesis because of its Texas Instruments LPC Speech Chips which were used in its Speak & Spell toys. A plug-in speech synthesizer module was available for the TI-99/4 and 4A. Speech synthesizers were offered free with the purchase of a number of cartridges and were used by video games such as Alpiner and Parsec. Alpiner's speech includes male and female voices and can be sarcastic when the player makes a bad move.
The synthesizer uses a variant of
History
In 1977, groups within Texas Instruments were designing a
Others within the company persuaded the Lubbock group to use TI's TMS9900 CPU. This was in keeping with TI's "one company, one computer architecture" concept, where a single processor model would scale from consoles to its high-end minicomputers. The TMS9900 is a single-chip implementation of TI's 16-bit
Meanwhile, another home computer product was emerging from TI's European headquarters, where a third party consulting firm was contracted to produce a prototype
99/4
In 1979, TI was a successful manufacturer of large computers
Through the development period, several companies attempting to enter the home computer market were faced with significant pushback from the Federal Communications Commission (FCC). The FCC had developed new rules for consumer devices that connected directly to televisions in an effort to control ongoing complaints about interference by poorly shielded devices. Televisions of the era generally had only a single antenna input, and thus connecting to them required the internal video signal of the device to be converted to radio frequency using an RF modulator. The resulting signals were often poorly shielded and signal leakage could be picked up in the antennas of nearby televisions.[18]
The new rules were extremely difficult to meet. TI continued battling the FCC both in the lab and in Congress, where it had considerable power due to its position within Texas's high-tech industry. It failed to meet the FCC requirements as the release date approached. The company eventually gave up and bundled a modified Zenith Electronics television as a computer monitor, eliminating the need for the RF modulator that generates the interference by connecting directly to the TV's circuitry using a composite video signal. This put the introductory price at US$1,150 (equivalent to $4,253 in 2023).[19]
The 99/4 sold poorly. Very little software was available, as few developers ported their products to its 16-bit CPU.
99/4A
Two years after the 99/4's debut, TI released the 99/4A. It adds a typewriter-style keyboard—keeping the non-standard layout—and more expansion options. The expansion system extends from the right side of the chassis, with modules that can be daisy-chained. There is a practical limitation to this, because each module increases the width of the system. The price was initially US$525, less than half that of the 99/4.[5]
TI continued lowering the price through 1981, first to $449.95, and then to $399.95 in early 1982, in competition with Commodore's $300 VIC-20. This turned into a price war with Commodore. TI responded by cutting the wholesale price of the 99 by $100, while also offering a $100 rebate directly to consumers, lowering the street price to about $200. Bill Cosby in advertising for TI marketed the refund.[23][5][24] By mid-1982, Jerry Pournelle wrote that TI was "practically giving away the TI-99/4A".[25] An industry joke stated that the company was losing money on each computer, but was making up for it in volume.[5][23] Commodore matched the $200 price in December 1982.[5]
TI celebrated the 99/4A's market success at the January 1983 Consumer Electronics Show in Las Vegas, where Cosby joked how easy it was to sell a computer by paying people $100 to buy one.[23][5] Sales peaked at 30,000 a week that month, but on 10 January 1983 Commodore lowered the price of its computers. In February TI responded with a 99/4A retail price of $150. In April, the VIC-20's bundled retail price reached $100 and the 99/4A followed suit. In the spring of 1983, TI attempted to reduce the parts count to maintain a competitive edge by combining multiple chips into a single custom chip, renaming the 4A PCB as a "QI" (Quality Improved) board and began production of plastic beige cases without the former aluminum trim of the black console. In May, it began offering the PEB for free with the purchase of three peripherals. In August the company reduced prices of peripherals by 50% and offered $100 of free software; in September, it reduced software prices by up to 43%.[23][5][26]
Lack of third-party development
The president of
TI did not provide an editor, assembler, or hardware technical information when it released the computer. Pournelle stated that "TI's message is loud and clear: 'Drop dead, hobbyists!'",
Pournelle added, "TI had rightly concluded that the hobbyists and hackers were a tiny part of the market and wrongly concluded that they were therefore unimportant".[25] Rivals were more open with information. Kilobaud Microcomputing reported that a Commodore executive promised the VIC-20 would have "enough additional documentation to enable an experienced programmer/hobbyist to get inside and let his imagination work".[31][28] Even when competitors did not disclose technical information, because their computers used commercial off-the-shelf parts like MOS 6502 and Zilog Z80, much more information was public than for TI's proprietary components.[20] IBM learned from TI's mistake, Pournelle said. The company released software and hardware technical information when the IBM PC was announced in 1981,[25] stating that "the definition of a personal computer is third-party hardware and software".[32]
TI had also learned from its mistake and no longer ignored hobbyists, Pournelle said in 1982.
No official technical documentation from TI was released until the "Editor/Assembler" development suite was released in 1981, and no system schematics were ever released to the public until after TI had discontinued the computer.
Discontinuation
After TI in mid-1983 unexpectedly announced a $100 million loss in the second calendar quarter—implying a pretax loss from home computers of $200–250 million—its stock dropped by one third in two days. The Times stated in June 1983 that Cosby's $100 refund "joke is no longer funny", and that "future options are slim". The low price affected the 99/4A's reputation; "When they went to $99, people started asking 'What's wrong with it?'", one retail executive said. An L.F. Rothschild sell-side analyst estimated that TI had prepared to manufacture three million computers in 1983, but would only be able to sell two million.[23]
Some observers predicted after the second quarter's loss that the 99/4A would not be able to recover; even if the company did not plan to discontinue the computer, the fear that it would become
A total of 2.8 million units were shipped before the TI-99/4A was discontinued in March 1984,[1][37] perhaps the largest installed base among all personal computers.[26] The 99/4A became the first in a series of home computers to be orphaned by their manufacturer over the next few years, along with the Coleco Adam, Mattel Aquarius, Timex Sinclair 1000, and IBM PCjr.
Architecture
The TMS9900's
At the time of launch, the system included only a single user-accessible programming language: TI's built-in BASIC interpreter, written in GPL. On the Creative Computing Benchmark, it runs at roughly half the speed of the Apple II.[38]
Technical specifications
CPU
Memory
- 8 KB of monitor ROM and GPL interpreter
- 8 KB of RAM, if memory expansion is attached
- 8 KB allocated to expansion devices (e.g. disk drive controller)
- 8 KB allocated to ROM/RAM in expansion cartridges
- 256 bytes scratchpad RAM for the CPU
- Memory ports for Video Display Processor, sound, speech etc.
- 24 KB RAM, if memory expansion is attached
- 16 KB Video Display Processor RAM accessible via the VDP (not in CPU's memory map)
Video
- 32 single-color sprites in defined layers allowing higher-numbered sprites to transparently flow over lower-numbered sprites. Sprites are available at 8×8 pixels or 16×16 pixels, with a "magnify" bit that doubled all sprites' size but not their resolution. A single bit is available in hardware for collision detection, and the console supports automatic movement via an interrupt routine in the ROM. There can only be 4 visible sprites per scan line.
- 16 fixed colors (15 visible, one color reserved for "transparent" which shows the background color). Transparent is intended for the 9918's genlock which is disabled in the system.
- Text mode: 40×24 characters (256 6×8 user-definable characters, no sprites, foreground and background color only, not accessible in BASIC, standard in the p-system/Pascal, assembly editor and word processor)
- Graphics mode: 32×24 characters (256 8×8 user-definable characters, full 15 color palette + transparent (available in groups of 8 through the character table) and 32 sprites (The only mode available in BASIC. Extended BASIC is required for sprites, and can access only 28 of them.)
- Bitmap mode: 256×192 pixels (no more than two colors in an eight-pixel row, full 15 color palette + transparent, all 32 sprites available but interrupt-based motion through the ROM routine is not due to the memory layout, not available to BASIC or the original 9918).
- Multicolor mode: 64×48 pixels (each pixel may be any color, all 32 sprites are available)
- All of the above comprise 36 layers starting with the video overlay input, then the background color, then two graphics mode layers, then a layer for each of the 32 sprites. A higher layer obscures a lower layer in hardware, unless that higher layer is transparent.
Sound
TMS9919, later
- 3 voices, 1 noise (white or periodic)
- Voices generate square waves from 110 Hz to approximately 115 kHz
- Console ROM includes interrupt-driven music playback
Games
Roughly 100 games were published for the TI-99/4A, with most published by Texas Instruments.[39] Some of the games released only for the 99/4A are Parsec, Alpiner, Tombstone City: 21st Century, Tunnels of Doom, and The Attack. TI Invaders and Car Wars are TI's renditions of Space Invaders and Head On respectively. Munch Man is similar to Pac-Man, but the title character fills the maze with a pattern rather than emptying it of dots.
Tigervision offered a solution to the memory limitation of the standard cartridge slot in the form of a 24 KB memory expansion cartridge that attached to the side expansion interface, emulating an expansion device. This allowed the company to implement a larger game completely in machine code, which was used for Espial and Miner 2049er. Exceltec also released two similar side cartridges: Arcturus[40] and Killer Caterpillar.
The media criticized the computer's game library as mediocre.[5][39] TI not only discouraged third-party development, including games, but it also failed to license popular arcade games like Zaxxon and Frogger.[23]
Unreleased hardware
Hex-Bus
The
TI-99/4A successors
The TI-99/4 was intended to fit in the middle of a planned range of TI-99 computers, with prototypes and documentation created for other models. Initial plans were for a lower-end TI-99/2 and a more powerful TI-99/8. Later ideas for expanding the range included a bargain-priced TI-99/3, a terminal TI-99/7, and a direct follow-up to the TI-99/4A referred to as either TI-99/4B or TI-99/5.[41]
At the time they left the home computer market, TI had been actively developing two successors to the TI-99/4A that went through several prototypes but never entered production. Some of these prototypes are now in the hands of TI-99/4A collectors. Both machines would have been substantially faster than the original TI-99/4A and used the Hex-Bus serial interface.
- TI-99/2,Mylar keyboard. TI designed the computer in four and a half months to sell for under $100 and compete with the Sinclair ZX81 and Timex Sinclair 1000. Based on the TMS9995 CPU running at 10.7 MHz and with a built-in RF modulator, performance greatly increased when the screen was blank. The University of Southwestern Louisiana developed system software. 99/2 software ran on the 99/4A, but not vice versa. Working prototypes appeared at the January 1983 Consumer Electronic Show (CES).[43] Home-computer prices declined so quickly, however, that by mid-1983 the 99/4A sold for $99.[44][23] The company canceled the 99/2 in April 1983,[26] but planned to exhibit it at the June CES until other companies' press conferences there indicated that competition would increase.[27]
- TI-99/8 and 99/6.[45][27] The 99/8 reportedly had a $200 wholesale price.[5] Privately shown to dealers but not announced at June CES, it was formally canceled in October 1983. It included 64 KB of RAM[26] expandable to 15 megabytes, a larger keyboard, built-in speech synthesis, built-in UCSD Pascal operating environment, and the full 16-bit data bus available on the expansion port. It was abandoned in the prototype stage. The Multi Emulator Super System is capable of running what are believed[by whom?] to be the system's ROMs.
Legacy
The Tomy Tutor and its sibling systems are Japanese computers similar in architecture and firmware to the 99/8. Unlike the 99/8, it was released commercially, but sold poorly outside Japan. Portions of the operating system and BASIC code are similar to the 99/8.
Until 2006, there was an annual Chicago TI Faire[46] where people celebrated the TI-99 family of computers.
Post-TI development
The Myarc
The Second Generation CPU card (SGCPU) was released by the System 99 User Group in 1996 as a card to be installed in the PEB.[citation needed]
In 2004, a
A range of plug-in cartridge boards have been developed, allowing software projects to be distributed on cartridge.[48][49]
The Phoenix G2,
An FPGA-based TMS9918 compatible graphics chip, called the F18A, is a drop-in replacement for the original 9918 VDP, but features VGA output, bypassing the TMS9918A's native composite output, and contains other enhancements such as removal of the restriction of 4 sprites per scan line.[51]
See also
- Compact Computer 40 (1983)
- Texas Instruments Professional Computer (1983 – c. 1985)
- Texas Instruments Professional Portable Computer (1983)
References
- ^ a b Steve's Old Computer Museum!
- ^ Bryan Roppolo Boulder. "1979 TI-99/4 Home Computer Literature". Ti994.com. Retrieved 2019-10-28.
- ^ a b c d "Death of a Computer," April 1984, Texas Monthly, retrieved September 20, 2023
- ^ Texas Instruments TI-99/4, First 16-bit Home Computer, Old-Computers.com, archived from the original on 13 March 2017, retrieved 23 September 2014
- ^ a b c d e f g h i j k l m n o Ahl, David H. (March 1984). "Texas Instruments". Creative Computing. pp. 30–32. Retrieved 6 February 2015.
- ^ TI-99/4A Console Technical Data. Texas Instruments Inc. 1983. p. 10.
- ^ a b c d Rhines, Walden (22 June 2017). "The Inside Story of Texas Instruments' Biggest Blunder: The TMS9900 Microprocessor". IEEE Spectrum.
- ^ a b c "The TI-99/4A internal architecture". 16 August 2000.
- ^ TI-99/4A Console Technical Data. Texas Instruments Inc. 1983. p. 4.
- ^ a b Mace, Scott (1984-04-09). "Atarisoft vs. Commodore". InfoWorld. p. 50. Retrieved 4 February 2015.
- ^ "Getting Started with the TI-99/4A". 1983.
- ^ Getting Started with the TI-99/4A, 1983
- ^ "TI‐99/4A user‐dismantled PEB", 99er
- ^ Rhines, Walden C. (2017-06-22). "The Texas Instruments 99/4: World's First 16-Bit Home Computer". IEEE Spectrum. Archived from the originalon 2017-07-21. Retrieved 2017-07-08.
- ^ "1980s Trends in the Semiconductor Industry". Semiconductor History Museum of Japan. Retrieved 10 July 2019.
- ^ Pollack, Andrew (14 January 1984). "Founder of Commodore Resigns Unexpectedly". The New York Times.
- ^ Schuyten, Peter (6 December 1978). "The Computer Entering Home". The New York Times.
- ^ Federal Communications Commission Reports: Decisions, Reports, and Orders of the Federal Communications Commission of the United States (Extensive coverage of the FCC's dealings with consumer electronics is covered in this later work). FCC. 1983.
- ^ Knight, Daniel (19 December 2015). "Texas Instruments' Personal Computers".
- ^ ISBN 978-1-4214-4353-9.)
{{cite book}}
: CS1 maint: date and year (link - ^ Osborne, Adam (1980-07-07). "Radio Shack's Videotex". InfoWorld. pp. 9, 28. Retrieved 15 February 2016.
- ^ Hogan, Thom (1981-09-14). "State of Microcomputing / Some Horses Running Neck and Neck". pp. 10–12. Retrieved 2019-04-08.
- ^ a b c d e f g h i j k l Pollack, Andrew (1983-06-19). "The Coming Crisis in Home Computers". The New York Times. Retrieved 19 January 2015.
- ^ Texas Instruments TI-99. 2007-06-01 – via YouTube.
- ^ a b c d e f Pournelle, Jerry (July 1982). "Computers for Humanity". BYTE. p. 392. Retrieved 19 October 2013.
- ^ a b c d e f g Mace, Scott (1983-11-21). "TI retires from home-computer market". InfoWorld. pp. 22, 27. Retrieved 2011-02-25.
- ^ a b c d e Mitchell, Peter W. (1983-09-06). "A summer-CES report". Boston Phoenix. p. 4. Retrieved 10 January 2015.
- ^ a b Thornburg, David D. (April 1981). "The Commodore VIC-20: A First Look". Compute!. p. 26.
- ^ a b c d Pournelle, Jerry (July 1983). "Interstellar Drives, Osborne Accessories, DEDICATE/32, and Death Valley". BYTE. p. 340. Retrieved 28 August 2016.
- ^ Green, Wayne (August 1980). "Publisher's Remarks". Kilobaud. p. 8. Retrieved 23 June 2014.
- ^ "Commodore: New Products, New Philosophies". Kilobaud. September 1980. pp. 26–28. Retrieved 23 June 2014.
- ^ Bunnell, David (April–May 1982). "Boca Diary". PC Magazine. p. 22. Retrieved 21 October 2013.
- ^ "IBM's Peanut Begins New Computer Phase". Boston Globe. Associated Press. 1983-11-01. p. 1.
- ^ Kleinfield, N. R. (1984-12-22). "Trading Up in Computer Gifts". The New York Times. Retrieved 5 February 2015.
- ^ Rosenberg, Ronald (1983-12-08). "Home Computer? Maybe Next Year". The Boston Globe.
- ISSN 0362-4331. Retrieved 2017-07-02.
- ^ TI-99 Home Computer Timeline Bill Gaskill
- ^ Knight, Daniel (10 January 2016). "How Fast Were Those Late 1970s Home Computers?". Low End Mac.
- ^ a b Mace, Scott (1984-05-07). "In Praise of Classics". InfoWorld. p. 56. Retrieved 6 February 2015.
- ^ "Cartridge pictures", TI‐99/4A home computer, Hex bus
- ^ Shaw, Stephen. "Home Computing with Texas Instruments". stephen.shawweb.co.uk. Retrieved 26 February 2022.
- ^ "99/2", 99er
- ^ Littlejohn, Harry; Jander, Mark (June 1983). "Texas Instruments' 99/2 Basic Computer". BYTE. p. 128. Retrieved 19 October 2013.
- ^ Lock, Robert (June 1983). "Editor's Notes". Compute!. p. 6. Retrieved 30 October 2013.
- ^ "99/8", 99er
- ^ "Faire", TI‐99, Main byte
- ^ OldComputers (online museum)
- ^ "Hardware projects", TI‐99/4A home computer, Hex bus
- ^ You Tube
- ^ "G2", TI‐99 UG, UK, archived from the original on 2010-09-19
- ^ "Archives", Code hack create
External links
Media related to Texas Instruments TI-99/4A at Wikimedia Commons
- Ninerpedia wiki devoted to the TI-99 series
- 1979 TI-99/4
- The TI-99/4A Home Computer Page