Texas Instruments TI-99/4A - Features

Features

The TI-99/4A's CPU, motherboard, and ROM cartridge ("Solid State Software") slot were built into a single console, along with 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 "coffee cup warmer". The external power supply, which was different according to the country of sale, was merely a step-down transformer.

Available peripherals included a 5¼" floppy disk drive and controller, an RS-232 card comprising two serial ports and one parallel port, a P-code card for Pascal support, a thermal printer, an acoustic coupler, a tape drive using standard audio cassettes as media, and a 32 KB memory expansion card. The TI-99/4 was sold with both the computer and a monitor (which was a modified 13" Zenith Color TV) as Texas Instruments could not get their RF Adapter FCC approved.

In the early 1980s, TI was known as a pioneer in speech synthesis, 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 Parsec). The synthesizer used a variant of linear predictive coding and had 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 text-to-speech in the Terminal Emulator II cartridge cancelled that plan. (Most speech synthesizers were still shipped with the door that opened on the top, although very few had the connector inside. There are no known speech modules in existence for those few units with the connector.) In many games (mostly those produced by TI), the speech synthesizer had relatively realistic voices. As an example, Alpiner's speech included male and female voices and could be quite sarcastic when the player made a bad move.

The TI-99/4A's original expansion concept was that peripherals would be connected serially to the console and each other, in a 'daisy-chain' fashion. The 'sidecar' expansion units could be connected together in a continuing chain, but could 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 plugged 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 had its own "access light", a LED which would blink or flicker when the card was being used by software. As on the earlier S-100 bus, the section of the power supply that powered the card slots was unregulated. Each card had on-board regulators for its own requirements, thus reducing power consumption on a partially loaded PEB and allowing for future expansion cards which might have unusual voltage requirements.

Even more unusual was an analog sound input on the expansion bus. This allowed the TI Speech Synthesizer's audio to be carried through the console to the monitor. The audio was also carried through the ribbon cable ("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.

Early models (the TI-99/4, identified by its keyboard and "(C)1979 TEXAS INSTRUMENTS" on the title page) included a built-in equation calculator, but in the 99/4A ("(C)1981 TEXAS INSTRUMENTS") this feature was discontinued. All consoles included TI BASIC, a strict ANSI-compliant BASIC programming language interpreter which was largely incompatible with the more popular, and frequently imitated, Microsoft BASIC. Later consoles, identified by "(C)1983 TEXAS INSTRUMENTS V2.2" on the title page, also removed the ability for the system to execute unlicensed ROM-based cartridges, locking out third-party manufacturers such as Atarisoft.

The system also supported saving to, and loading from two cassette drives through a dedicated port, and had a joystick port that supported two digital joysticks, which TI referred to as "wired remote controllers". The two joysticks were connected through a single nine pin port, which therefore supported only TI joysticks directly. Aftermarket adapters were available which allowed the use of two Atari-compatible joysticks. Composite video and audio were output through another port on NTSC-based machines, and combined by an external RF Modulator for use with a television. PAL-based machines output a more complex YUV signal which is also modulated to UHF externally.