Being a very popular personal computer, the TI-99/4A is still very common and cheap to buy. On the other hand, the first TI-99 from 1979, the TI-99/4 (note the lack of 'A'), is far less common.
In the late 1970s, personal computers were starting to take off, with plenty of options from an array of companies. The was an early entrant, popular among techie users and developers. Others, including Radio Shack’s (referred to by its critics as the Trash 80), the Apple I and II, and the, sold to a more mainstream set of customers. Industry watchers expected TI to have a big impact on the market— if it managed to introduce a competitive product. By 1977, TI engineers were hard at work on not just one computer design but three: 1) a low-end video game console intended to sell for under US $200, with games stored on ROM cartridges; 2) a personal computer aimed at hobbyists and users of Radio Shack and Apple computers; and 3) a high-end business computer with nearly 10 megabytes of hard disk storage. As tends to happen in large companies, turf wars broke out.
The boundary between the video game and home computer groups, both of which were competing for resources in TI’s facility in Lubbock, Texas, began to grow fuzzy. Meanwhile, the business computer’s intended market clearly overlapped with that of the minicomputer and portable terminal products, which came out of TI’s Data Systems Division. Ultimately, the video game and personal computer efforts merged, and the business computer was moved to the Data Systems Division, where it was viewed with hostility and subsequently killed. The surviving home computer group, whose product was now known as the 99/4, started receiving lots of corporate “help,” including pressure to use TI’s. Peter van Cuylenburg, who was in TI’s European marketing division, came up with an innovative solution to this corporate pressure. He commissioned a third-party contractor to design and build a personal computer, code-named “Mojo,” using only chips made by TI. The contractor used TI’s version of the Intel 8080A in addition to lots of TI TTL, memory, and other components.
While Mojo sort of solved the desire for corporate synergy between the company’s semiconductor and consumer products groups, the TMS9900 was more genuinely a TI microprocessor. And so after a series of discussions and compromises, the Mojo idea was discarded, and the 99/4 ended up using the TMS9900 as well as the.
The 99/4 also ended up with a combination of features from the original video game design (including an ultracheap keyboard, RF clips to attach to a TV set, and ROM-based applications). When the 99/4 finally emerged in 1979, having somehow transcended three sets of TI management, it received mostly disparaging reviews. Of Morgan Stanley, who was then the leading semiconductor analyst and fast becoming the leading personal computer analyst as well, wrote a humorous article about the disappointment of what was expected to be a major contender in the personal computer business.
A revised version, the was released in 1981 with a better keyboard, but it wasn’t enough: In 1983, the New York Times called the 99/4 “an.” Photo: Robert Clay/Alamy Embarrassing Failure: Texas Instruments had high hopes for its TI 99/4, which debuted in 1979, and the follow-on 99/4A shown here. But the machines performed poorly and the company took a $330 million write-off before exiting the home computer market.
Despite being the world’s first 16-bit home computer, the 99/4, like the microprocessor on which it was based, was a dog. Intended to satisfy two very different markets, the 99/4 and 99/4A served neither one well. Unsurprisingly, initial sales were weak. By 1982 Commodore had initiated a price war with its computer, forcing TI to first offer $100 rebates and eventually slash the price from an initial $1,150 to an unsustainable $49.
The price war was an incredible boon to consumers, because it made personal computers affordable to a much wider market. TI saw sales of the 99/4A explode, eventually reaching 2.8 million units. But the 99/4 and 99/4A were expensive to build, and the company lost money on each home computer it sold. One reason they cost so much to build was the high cost of the TMS9900’s unconventional packaging. Specifically, the large number of connecting pins for a 16-bit microprocessor forced TI to develop its own packaging technology. By the time others entered the 16-bit microprocessor market, standard packaging configurations had been developed to overcome this problem.
The 9900 also had some performance issues because of its unique “memory to memory” architecture, which used off-chip memory instead of on-chip registers, thus slowing performance. The that followed the TMS9900 overcame some of these problems with an on-chip register file cache, but there was no easy way to substitute the TMS9995 for the TMS9900 in the TI-99/4 architecture. Meanwhile, most third-party software developers remained reluctant to invest in programs for the 99/4A. As demand for the 99/4A soared, TI initiated a crash program to ramp up production. But it couldn’t compete with Commodore, which had a low-cost design and continued to lower the prices for its computers even further. Just as TI’s production output took off, demand for the 99/4A began to fade.
In 1983 the company took a, and it abandoned the home computer business the following year. Ironically, by then the TI machine had a devoted following among users who had purchased the 99/4A because they couldn’t resist its low price. Still exist today. Interestingly, the used in the 99/4 series found broad usage in the for home computers, which also used a Zilog Z80 microprocessor and the CP/M operating system from Digital Research.
The MSX architecture was the brainchild of, who founded a publishing company called ASCII Corp., which later became ASCII Microsoft. The TMS9918 graphics chip, designed by TI’s, was central to the MSX standard and eventually was used in products from game manufacturers like Coleco and Sega, as well as Sony, Yamaha, and Toshiba. Had the IBM PC never come along, the MSX standard might have been much more broadly adopted. About the Author is chairman and CEO of, in Wilsonville, Ore.
1979 TI-99/4 with, optional Speech Synthesizer, keyboard overlays, and a cartridge Type Release date June 1981 ( 1981-06) (TI99/4 in October 1979) Introductory price $525 (equivalent to $1,400 in 2018) Discontinued March 1984 Media @ 3.0 MHz Memory 256 bytes 'scratchpad' RAM + 16 VDP (graphics ) Graphics TMS9918A Predecessor TI-99/4 The TI-99/4A is a, released June 1981 in the United States at a price of $525 ($1,400 adjusted for inflation). It is an enhanced version of the less successful TI-99/4 model, which was released in late 1979 at a price of $1,150 ($4,000 adjusted for inflation).
Both models include support for and multi-channel sound, some of the first home computers to include such custom hardware, alongside the also introduced in 1979. Contents. Features The TI-99/4 has a -style and a character set that lacked lowercase text. The TI-99/4A added an additional graphics mode, 'lowercase' characters consisting of small capitals, and a full-travel keyboard. Both use 16-bit processors, making the TI-99/4 series the first 16-bit home computers. The TI-99/4A's, and ('Solid State Software') slot are built into the keyboard. The power regulator board is housed below and in front of the cartridge slot under the sloped area to the right of the keyboard.
This area gets very hot so users commonly refer to it as the ' warmer'. The external power supply, which was different according to the country of sale, is a step-down. Available peripherals included a 5¼' and controller, an card comprising two serial ports and one parallel port, a card for support, a, an, a using standard as media, and a 32 memory. The TI-99/4 was sold with both the computer and a (a modified 13' color televisioin) as Texas Instruments could not get its approved by the U.S. The TI-99/4A did ship with an RF modulator. TI-99/4A speech demo using the built-in vocabulary In the early 1980s, TI was known as a pioneer in, and a highly popular 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 many TI-written video games (notable titles offered with speech during this promotion were Alpiner and ).
The synthesizer uses a variant of and has a small in-built vocabulary. The original intent was to release small cartridges that plugged directly into the synthesizer unit, which would increase the device's built in vocabulary. However, the success of software in the Terminal Emulator II cartridge cancelled that plan.
In many games (mostly those produced by TI), the speech synthesizer has relatively realistic voices. For example, Alpiner 's speech includes male and female voices and can be quite sarcastic when the player made a bad move. TI-99/4 'PEB' or Peripheral Expansion Box The TI-99/4's original expansion concept was that peripherals would be connected serially to the console and each other, in a ' fashion. The 'sidecar' expansion units can be connected together in a continuing chain, but can rapidly occupy an entire desktop and cause crashes and lockups due to the large numbers of connectors on the system bus. This original idea was soon replaced by a system based on expansion cards.
Encased in silver plastic, but made from sheet steel, these plug into the bulky 'Peripheral Expansion System' (usually known among TI owners as the Peripheral Expansion Box or 'PEB'), an eight slot chassis, containing its own linear power supply and a full-height 5¼' floppy bay. Each card also has its own 'access light', an that would blink or flicker when the card was being used by software. As on the earlier, the section of the power supply that powers the card slots is unregulated.
Each card has on-board regulators for its own requirements, thus reducing power consumption on a partially loaded PEB and allowing for future expansion cards that might have unusual voltage requirements. The PEB also carries an analog sound input on the expansion bus.
This allows the TI Speech Synthesizer's audio to be carried through the console to the monitor. The audio is also carried through the ('firehose', as TI users often call it) to the Peripheral Expansion System, both allowing the relocation of the Speech Synthesizer to the Expansion box and allowing for the possibility of audio cards offering more features than the console's built-in sound. No 'official' cards from Texas Instruments ever made use of this line. Early models (the TI-99/4, identified by its keyboard and ' (C)1979 TEXAS INSTRUMENTS' on the title page) includes a built-in equation calculator, but in the 99/4A (' (C)1981 TEXAS INSTRUMENTS') this feature was discontinued. All consoles include, a strict -compliant programming language interpreter that is largely incompatible with the more popular, and frequently imitated,. Later consoles, identified by ' (C)1983 TEXAS INSTRUMENTS V2.2' on the title page, also remove the ability for the system to execute unlicensed -based cartridges, third-party manufacturers such as.
The system has a port that supports two digital joysticks, which TI referred to as 'wired remote controllers'. The two joysticks are connected through a single nine pin port which is identical with those used for joysticks but with incompatible pins. Aftermarket adapters were available which allow the use of two.
The computer supports saving to, and loading from, two cassette drives through a dedicated port. And audio are output through another port on -based machines, and combine through an external RF modulator for use with a television.based machines output a more complex YUV signal which is also modulated to UHF externally. 16-bit processor The TI-99/4 series is a 16-bit personal computer. The TI-99/4A has a running at 3.0. The TMS9900 is based on TI's range of mini computers. Only the, and workspace pointer registers are on the chip; all work registers are kept in at an address indicated by the workspace pointer. 16 registers are available at any given time, and a context switch instruction that changes to another workspace automatically allows fast context switches compared to other processors that may have to store and restore the registers.
For CPU RAM, the machine has only 256 bytes of 'scratchpad' memory to support the storage of workspaces. This memory is placed directly on the 16-bit bus with zero wait states, making it much faster than any other memory available to the system. Although the CPU is a full 16-bit processor, only the system ROMs and 256 bytes of scratchpad RAM is available on the 16-bit bus. All other memory and peripherals are connected to the through a 16-to-8-bit, requiring twice the cycles for any access and introducing an additional 4-cycle.
This is reportedly due to the failure of a new 8-bit processor being designed by TI for this system, while the 9900 processor was already in production and proven. A user modification in later years involves 'piggybacking' static RAM chips onto the console's 16-bit ROM chips, allowing a standard 32kB RAM expansion without the wait state and approximately a 30% speed increase for many applications. Applications previously running entirely in 8-bit RAM (both code and registers) can speed up by a factor of two. Most hardware is based on the system clock, not the program execution speed, and the hardware access still runs through the 8-bit bus with the wait states intact, so this particular modification does not affect any peripherals. The (VDP) in the 99/4 is a. It lacks a mode, which was added in the 99/4A. The VDP in the American 99/4A is the TMS9918A, giving the machine the 'A' in its name.
In the European consoles this is replaced with the, which also powered machines. A unique feature of these VDP chips is that they contain hardware support for superimposing on-screen graphics over other video signals. Although TI announced a peripheral card called the Video Controller Card to allow the control of select, which could switch between the TI's display and the LaserDisc player, the capability of the 9918 is disabled in the design of the 99/4A and requires hardware modifications to use. All accesses to the VDP system are executed eight bits at a time. Although this affects performance, it made it easier to upgrade the VDP when newer, relatively compatible chips were released.
Peripherals from Mechatronics, and Michael Becker, simply called '80-column cards' include the VDP, which gives the 99/4A a top resolution of 512×424 pixels in 16 colors or 256×424 pixels in 256 colors. This also increases the VDP memory from 16K to a maximum of 192K, although only software explicitly written for the 9938 takes advantage of it.
The unusual architecture of the 99/4 series is documented to be due to the failure of the 9985, an 8-bit processor created specifically for the machine. When it was abandoned, the 16-bit 9900 was selected to replace it, and a great deal of ' had to be added to fit the processor into the existing design, while no changes were made to take advantage of the 9900's strengths. 'Plug and play' hardware support. Daisy-chained Hexbus peripherals All TI-99 models, from the earliest TI-99/4 to the unreleased TI-99/2 and TI-99/8, include support for all peripherals. Device drivers (called 'Device Service Routines', or DSRs) are built into ROMs in the hardware; when a new card was inserted, it is immediately available for any software which needed or wanted to use it.
All device access utilize a generic file-based I/O mechanism, allowing new devices to be added without updating software to use it. The Communications Register Unit (CRU) can address 4096 devices; however, each TI card runs at a hard-wired address on the CRU bus, and so multiple cards of the same type cannot be supported without modification. The only official card known to be modifiable is the RS-232 card, which supports two different base addresses.
This allows the system to support four RS-232 ports and two parallel printer ports. Four-line were being run, using properly serial cards, on TI-99/4A systems as recently as the mid-1990s. Most hobbyist-created cards released after TI's exit from the personal computer business include switches to set the base CRU address.
The HexBus Interface was designed in 1982 and intended for commercial release in late 1983. It connects the console to peripherals via a high-speed serial link.
Though it is prototypical to today's (plug and play, hot-swappable, etc.), it was never released, with only a small number of prototypes appearing in collector hands after TI pulled out of the market. Several HexBus peripherals were planned or produced. A WaferTape drive never made it past the prototype stage due to reliability issues with the tapes. The 5.25-inch floppy drive also never made it past the prototype stage, even though it worked. Prototype DSDD disk controllers and Video controllers were also made. A four-color -, a 300- modem, RS-232 interface, an 80-column thermal/ink printer, and a 2.8' 'Quick Disk' drive were the only peripherals released in quantity, mostly for use with the (CC-40).
All HexBus peripherals can be used with a TI-99/4A when connected through the HexBus Interface, through direct connection to the TI-99/8, or through direct connection to the CC-40. CPU RAM and Scratchpad The TI minicomputer-inspired architecture of the TMS9900 series means that the 'Workspace' of registers currently in use are stored in main memory. Because static RAM was also very expensive in the early 80s, TI only gave the machines 256 bytes of fast 'scratch pad' RAM where register workspaces could be stored. The original design for the intended CPU had this 256 bytes internal to the CPU itself, but the 9900 requires registers to be in external memory. Placing this small amount of memory on the 16-bit bus nevertheless helps the performance of the machine (as compared to having registers in 8-bit RAM with a 4-cycle penalty for every access).
Some programs, such as Parsec, copied short loops of code to this memory to take advantage of the performance. The sidecar and PE box expansion systems makes possible an official 32kB RAM expansion.
This is not available to all uses – for example an Extended Basic program was restricted to using 24kB with the remaining 8kB available for machine code routines. Third parties provided replacement memory cards for the PEB.
For example, Myarc produced 192kB and 512kB cards. The memory provided by the Myarc cards can be partitioned for use as regular CPU RAM, a RAM disk and a printer buffer.
The Mini Memory plug-in module also contains 4kB of RAM that can be used as a persistent RAM disk (it contained a button cell) or to load a machine-code program. It is also possible to add an 8kB 'supercart' or 32kB 'superspace' cartridge via the cartridge slot, which also included the Editor/Assembler GROM. This uses the cartridge ROM space. VDP RAM and GPL Texas Instruments engineers afforded 16kB of (VDP) RAM to the TI99/4A's graphics, a. The VDP RAM was DRAM, with the VDP handling refresh. This is expandable to 192kB with the use of a as a user-designed modification (not a standard upgrade option). VDP RAM is also used for storing buffers for disk I/O, and variables and code for users' programs.
Hence, the largest BASIC program possible is less than 16kB. BASIC is implemented on the TI-99 series using a second called Graphics Programming Language (GPL). The GPL interpreter resides in the ROMs and takes control of the machine at power-up, and was very close to the native 9900 machine code, adding instructions to transparently access the different types of memory in the machine and perform higher level functions such as memory copy and formatted display. Users who install memory expansion still need to upgrade to the Extended BASIC cartridge to use it instead of VDP RAM. The same VDP is used in the and machines.
Further upgrade chips, the 9938 and 9958, were produced by Yamaha based on TI's design. Boards were created that took advantage of these new chips to upgrade the graphics capabilities of the TI-99/4A.
The 9938, the more common of the two upgrades, allow 512 × 424 pixels at 16 colours, or 256 × 424 at 256 colours. These upgrades are not a simple drop-in and replace; a small board including the replacement VDP and replacement VDP RAM (usually 128kB) is required. In addition, although the chips were largely software-compatible, certain bugs in the ROMs cause compatibility issues with the new chips. One board, the Mechatronic 80-column card featuring the 9938 require that the user press a button when entering TI BASIC.
Graphics Read-Only Memory Graphics Read-Only Memory is another set of memory accessed a single byte at a time through a dedicated memory port, and were auto-incrementing read-only devices. (There is also support in the console for 'GRAM', simulators for which were created by third parties later.) The vast majority of TI cartridges (Disk Manager 2, Editor/Assembler, TI Writer, most games) use this system, as does the console's TI-BASIC. Swapping the TI-BASIC GROM with a GROM removed from a favorite cartridge is a popular modification, as is installing several GROMs into one cartridge allowing a 'multicart', with all included GROMs being available in the boot menu.
Since the standard machine does not allow third party machine language support, programmers found their markets decidedly limited to those users who actually added more RAM to their systems. This limitation was alleviated as the price of 32 kB expansion card and a 4 kB 'Mini Memory' module eventually came down, but by then the market had moved over to other computers. Some sophisticated cartridges (for example Parsec, Alpiner, TI, ) include memory-addressable ROM which was available for machine code, primarily for games or applications which demand the speed of machine code. None of this memory is available to the user.
In general, ROM-equipped cartridges may be identified by having 28-pin ICs on the board, while the GROM ICs have 14 pins. A small number of cartridges also include a small amount of RAM (notably those games produced for the Milton Bradley MBX expansion system).
Tigervision developed a unique solution to the memory limitation of the standard cartridge slot; a 24kB 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.
Tigervision cartridges using the expansion port include Espial. A third cartridge, Sprinter, is listed in its 1984 catalog but was not released. Exceltec also released two similar side cartridges, Arcturus and Killer Caterpillar. Because of the speed bottlenecks (16-to-8-bit bus multiplexer) and the doubly interpreted BASIC, the TI-99 series gained a reputation for being quirky and eccentric, which endeared it to some and maddened others. Many people who had only experienced TI BASIC also considered it very slow, although assembly programs actually manage fairly good speed despite the hardware issues to overcome. Main article: Developers created about 100 99/4A games, most published by Texas Instruments.
Some of the most popular were,. Many TI-developed video games may be forced into by holding the shift key and pressing 838. In Alpiner, the player can select which mountain to climb.
838 (with or without SHIFT) in Star Trek gives a random but high level of torpedoes, shields, and warp-drive energy. InfoWorld criticized the computer's game library as mediocre. TI not only discouraged third-party development for the 99/4A, including games, it also failed to license popular arcade games like. History Background. The original TI-99/4, released in 1979. In 1977 groups within Texas Instruments were designing a, a home computer to compete against the TRS-80 and Apple II, and a high-end business personal computer with a hard drive. The first two groups merged at TI's consumer products division in; the 99/4's (according to ) 'ultracheap keyboard', and ROM cartridges came from the console design.
Others within the company persuaded the Lubbock group to use TI's TMS9900 CPU. 99/4 Although TI was much larger than any other personal-computer company when it entered the market in 1979, the $1,150 TI-99/4 was, in 1983 stated, 'an embarrassing failure'. Stated that it was 'vastly overpriced, particularly considering its strange keyboard, non-standard Basic, and lack of software'. Reported in July 1980 that despite poor sales TI had raised the price of a complete system to $1,400, making the computer more expensive than the more popular Apple II, which was available for as little as $950.
'Some dealers, who have offered the complete system (including the monitor) for less than the price of the Apple, have still been unable to sell it', he added. 99/4A price war. The updated TI-99/4A, released in 1981.
Two years after the 99/4's debut, TI released the 99/4A, very similar, but with a better keyboard and more expansion options. By lowering its price and offering rebates TI sold many more computers; it has been estimated that it had about 35% of the home computer market at its peak. In 1982 TI began a with by lowering the street price of the 99/4A to $200, including a $100 rebate, to compete against the $300. TI spokesman joked how easy it was to sell a computer by paying people $100 to buy one, but the company continued to lose shelf space, as Commodore matched the $200 retail price by December 1982. The president of later said that 'TI got suckered by', head of Commodore.
TI was forced to sell the 99/4A for about the same price as the VIC-20, even though it was much more expensive to manufacture. Although TI and Commodore each owned their own fabrication facilities, Commodore created custom ICs to reduce the cost of its computers, while TI continued to use components and make only relatively small revisions to their motherboards.
Commodore also made other cost-cutting changes, including using aluminized cardboard to build RF shields for some of their systems. The TMS9900 required expensive custom; TI continued to use high-quality components and materials with the unfulfilled hope that the marketplace would recognize it. By mid-1982 wrote that TI was 'practically giving away the TI-99/4A'. An industry joke stated that the company was losing money on each computer, but was making up for it in volume. The 99/4A's list price was $400 that autumn, but the street price including $100 rebate was about $200. Sales peaked at 30,000 a week in January 1983, but on 10 January 1983 Commodore lowered the price of its computers; the VIC-20's wholesale price was $130.
In February TI responded by lowering the 99/4A's retail price to $150. In April Commodore again lowered prices, and the VIC-20's bundled retail price reached $100. TI also lowered prices and offered rebates, reducing the 99/4A's retail price to under $100; by this time the company was likely losing money on each computer.
In early 1983 TI stopped sales for a month to correct a defect, but—predicting in April that the home-computer market that year would be much larger than most industry analysts expected—continued production at an annual rate of three million, increasing inventory. In May it began offering the PEB for free with the purchase of three peripherals; by this time TI was using price cuts as the 99/4A's primary marketing. 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%. Discontinuation The Times stated in June 1983 that Cosby's $100 refund 'joke is no longer funny', and that 'future options are slim' for TI; Banking firm estimated that the company would only sell two million computers. The low price probably hurt the 99/4A's reputation; 'When they went to $99, people started asking 'What's wrong with it?' ', one retail executive said. After losing $111 million after taxes in the third calendar quarter of 1983, TI announced in October 1983 that it was discontinuing the 99/4A, while continuing to sell the -compatible computer.
(TI stock rose by 25% after the announcement, because the company's other businesses were strong.) With another TI price cut, retailers sold remaining inventory of the former $1,150 computer during Christmas for $49; 's 90 stores almost immediately sold more than 40,000 computers at the price, and a riot almost broke out at a as shoppers fought over the computer. Discontinued during the, the 99/4A became the first in a series of home computers to be by their manufacturer over the next few years, along with the,. A total of 2.8 million units were shipped before the TI-99/4A was discontinued in March 1984.
Lack of third-party development The TI-99/4A is more sophisticated than the VIC-20, offering more memory and more advanced graphics capabilities. However, a number of elements of its design attracted criticism. Peripherals plug directly into the right-hand side of the unit, unless the user purchased the expensive and heavy Peripheral Expansion Box. This design choice causes the computer to not fit well on top of a desk if the user adds more peripherals besides a tape drive and a printer.
In addition, the 48-key keyboard layout does not match that of a very closely. Finally, there was no option for an 80-column display at the time of its introduction. The keyboard and display limitations made it unpopular for. TI could not make a profit on the TI-99/4A at a price of $99, but hoped that selling many inexpensive computers would increase sales of more profitable software and peripherals. Because such a requires that, TI kept strict control over development for the machine, discouraging hobbyists and third-party developers. A executive said that the 99/4A had 'the worst software in the business', and Ahl noted that unlike other computers, it did not have ', or any popular games'.
Citing, publisher of reported in August 1980 that TI planned to have only 100 applications available by the end of 1981, stating that 'This tiny figure has to put a chill on the whole industry'. Its peripherals cost about twice as much as for other computers. TI joysticks, for example, were of poor quality and difficult to find; one reseller reported that its best-selling product was the Atari adapter cable.
Green said that although his company had published 'hundreds of programs for the and want to translate as many as possible for use on the TI-99/4', it could not find anyone among more than 1,000 developers in its network who could port software to the computer, adding 'We understand the problems with the system and the efforts Texas Instruments made to make translation difficult'. Rival companies were much more open with information. The next issue of Kilobaud Microcomputing reported that a Commodore executive promised that the forthcoming VIC-20 would have 'enough additional documentation to enable an experienced programmer/hobbyist to get inside and let his imagination work'. IBM released complete software and hardware technical information for the when announcing it in 1981, stating that 'the definition of a personal computer is third-party hardware and software'. Pournelle in 1982 wrote that because 'well over half the really good stuff for microcomputers has come from hobbyists and hackers. Which TI had wrongly concluded that they were. Unimportant', it 'found itself cut off from the mainstream'.
He believed that TI recognized its mistake and would change. The company, however, insisted on itself selling others' software, which many developers refused to agree to. After ' games for the Atari 2600 became very successful, TI at the June 1983 announced that only cartridges with would work in the 99/4A. The predicted that 'most software developers just won't bother making TI-compatible versions of their programs'.
Pournelle wrote after the announcement that 'TI once again tells the hobbyists to drop dead'. No official technical documentation from TI was released until the 'Editor/Assembler' assembly language development suite was released in 1981, and no system schematics were ever released to the public until after TI had discontinued the computer.
In addition, the TI-99/4A's awkward architecture and nonstandard CPU (as opposed to the and which all programmers of the day were familiar with) made it difficult to develop for. Cult following The TI-99/4A maintained a for years after its death in the marketplace, in part because of its eccentricities, and in part because TI had actively supported a network of user groups during the production of the machine. It eventually came to achieve a cult following among retro-computer hobbyists. In 2004 a Universal Serial Bus (USB) card and controller for for the PEB were released, and there is still an annual Chicago TI Fair where people congregate to celebrate the historic TI-99 family of computers. Third-party devices such as expanded memory cards, improved floppy controllers, and hardware are very stable and popular additions to the machine, although there are no current known sources for these devices.
In the early 1980s, a , developed by Ralph Fowler of, running on the 99/4A became very popular and brought many users together. Also, a number of for the TI-99 exist today for PC-based systems.
In 1987, the 'Turbo XT' was introduced by Triton. Though rare, it allowed a TI-99/4A and an to share the same desktop space, though without sharing such things as memory or disk drives. The Turbo XT had at least two serious failings — first, it extended the use of the TI's already marginal keyboard to the XT whereas the reverse would have probably been far more marketable; second, it did not allow the TI to share or use resources with the XT (custom BIOS might have allowed the XT to serve as ramdisk, diskette controller/drives and serial ports). Successors and clones.
See also: and At the time they left the home computer market, TI had been actively developing two successors to the TI-99/4A. Neither entered production, though several prototypes of each are in the hands of TI-99/4A collectors. Both machines would therefore have been substantially faster than the original TI-99/4A, and both were to use TI's 'HexBUS' serial interface (which was available as an option on the TI-99/4A and could be viewed as a prototype for today's ubiquitous — the link for the TI-99/8 includes some images of HexBUS peripherals). TI-99/2, a 4K RAM, 32K ROM computer with no color, sound, or joystick port and a keyboard. TI designed the computer in four and one half months to sell for under $100 and compete with the.
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 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). Home-computer prices declined so quickly, however, that by mid-1983 the 99/4A sold for $99. The company canceled the 99/2 in April 1983, but planned to exhibit it at the June CES until other companies' press conferences there indicated that competition would increase.
TI-99/8 and 99/6 The 99/8 reportedly had a $200 wholesale price. Privately shown to dealers but not announced at June CES, and formally canceled in October 1983. With 64 kB of RAM expandable to 15, larger keyboard, built-in speech synthesis, built-in Pascal operating environment with and the full 16-bit data bus available on the expansion port. Designed by Texas Instruments, but abandoned in the prototype stage. Some prototypes are known to exist. In addition, the emulator is capable of running what are believed to be the system's ROMs. Myarc, an enhanced TI-99/4A clone which was built by Myarc as a card to fit into the TI Peripheral Expansion System and used an IBM PC/XT detached keyboard.
Released in 1987, it was in many ways similar to the earlier TI-99/8 which was in prototype form in early 1983. It included a faster processor (12 MHz TMS9995), enhanced graphics with 80 column text mode (via 9938), 16-bit wide RAM, and was compatible with nearly all TI software and slot-mounted hardware (an adapter was available to allow the sidecar-only Speech Synthesizer to be installed inside the PEB). A toggle switch was mounted to the side of the PEB to allow insertion of wait states to bring the computer down to the same speed as the original console, allowing compatibility for games and other timing-critical software. SGCPU, the Second Generation CPU card was released by the System 99 User Group in 1996 as a card to be installed in the PEB. It was also known as the TI99/4P, and included standard 9900 CPU, ROMs, and up to 1 MiB of 16-bit RAM using the 'AMS' memory expansion scheme. This card required the HSGPL card, which provided the GROM emulation needed to run the system, and the EVPC, which included the 9938 video processor for display.
The and its sibling systems were Japanese computers very similar in architecture and firmware to the 99/8. Unlike the 99/8, it was released commercially, but sold very poorly outside Japan.
Portions of the operating system and BASIC code are similar to the 99/8. According to Barry Boone (a well known programmer for the TI-99/4A), the Tutor's built-in BASIC uses the same internal one byte tokens as does TI's Extended BASIC, and many of the memory scratchpad locations are placed at the same relative locations as the TI-99/4A and TI-99/8. For instance, keyscan values are returned at offset 75 and floating point is stored at 4A. The Phoenix G2, designed in 2010 by Gary Smith, a member of TI-User Group UK. This machine uses two FPGAs to emulate the entire architecture of the Myarc Geneve 9640 and the TMS9995 microprocessor, thus eliminating reliance on obsolete silicon devices. It incorporates the latest advances in technology, such as SD card readers, ethernet, full VGA output, and now 64 MB RAM. Technical specifications.
CPU: TI, 3.0, 64-pin. Memory: 16 kB VDP RAM (Video Display Processor RAM), plus 256 bytes CPU fast 'scratchpad RAM' intended for the TMS9900 processor to maintain register 'workspaces'. Video: TI VDP (TMS9918 in the earlier 99/4, TMS9929/9929A in PAL versions, 40 pin. Distinct in being the only chip on the TI motherboard with a heat sink on all models. Early models also have a heat sink on the clock generator, the TMS9904.). 32 single-color 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 coincidence (collision detection), and the console supports automatic movement via an interrupt routine in the ROM. There can be no more than 4 visible sprites per horizontal. 16 fixed colors (15 visible, one color reserved for 'transparent' which shows the background color). Transparent is intended for the 9918's functionality used in conjunction with TI's Video Controller Card. This feature was demonstrated in October 1999 at an international TI meeting near Stuttgart, Germany. (This requires a hardware modification to the console itself, as the video input line is not routed on the motherboard.).
Text mode: 40×24 characters (256 6×8 user-definable characters, no sprites, foreground and background color only, not accessible in BASIC). 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). Bitmap mode can be arranged in such a way as to use less memory but still provide improved color or improved pattern layout, leading to the popularity of so-called 'half-bitmap' modes.
In fact these modes are not undocumented modes of the VDP (which fully documented this masking) but simply clever layout of Bitmap mode. 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: TI TMS9919, later, identical to the used in many other systems. 3 voices, 1 noise (white or periodic).
Voices generate square waves from 110 Hz to approximately 115 kHz. Console ROM includes interrupt-driven music list playback. Contemporary use. Texas Instruments TI-99/4A computer. On display at the, EPFL, Lausanne. The TI-99/4A enjoys an active after-life in the vintage computing enthusiasts world.
There are currently three very active mailing lists where TI-99/4A owners correspond with each other, from matters concerning hardware setup and interfacing equipment to the machine, to advanced software techniques. TI-99/4A Programming Forum (AtariAge) – an active forum, with hardware and software projects on TI-99/4A. TI-99/4A Online User Group (OLUG) – a mailing list, with general chat on all things TI. TI-99/4A and Compatibles Discussion Group – a more technically oriented mailing list, where people will often post technical questions or software routines to try out.
SWPB Assembly Programmers Mailing List – the SWPB list is a mailing list dedicated to discussing machine code/assembly language programming on the TMS9900 CPU (SWPB is an assembly instruction, meaning 'swap bytes' in TMS9900 Assembly Language). Modern hardware developments There has been a resurgence in new hardware projects in recent years.
Recently, a range of plug in cartridge boards have been developed, allowing enthusiasts to distribute their software projects on cartridge for the first time in many years. Additionally, an audio card has been developed featuring the SID chip found in Commodore 64 computers, with a SID player/tracker software application in active development. Even more recently, a prototype system on a plug-in cartridge has been demonstrated at the 2010 Chicago Faire in America, although the intended feature set has not yet been announced. A new 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 enhanced features such as removing the 4 sprites on a scan line restriction of the original 9918. See also. References. 'TI‐99/4A user‐dismantled PEB',.
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'Archives',. External links Wikimedia Commons has media related to. – a wiki devoted to the TI-99 series home computers.
– website with many TI-99/4A pictures, including prototype equipment. – TI-99/4A website showing software cassettes, cartridges and TI99 resources. – a site with everything you wanted to know on the TI-99/4A's predecessor, the TI-99/4. – A site dedicated to the classic 1980's home computer, the TI-99/4A. Forum, links, downloads, and more., TI‐99 – another good site with hardware projects/hacks and descriptions. – recognizes those in the TI99'er Community who have contributed to the success of the Texas Instruments TI-99/4A and Myarc Geneve 9640 home computers.
– A large repository of gaming and edutainment software for the TI 99/4A.