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The Texas Instruments TI-99/4A is a home computer, released June 1981 in the United States at a price of $525 ($ adjusted for inflation). It's an enhanced version of the less successful TI-99/4 model, which was released in late 1979 at a price of $1,150 ($ adjusted for inflation). The TI-99/4 had a calculator-style chiclet keyboard 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 used 16-bit processors, making the TI-99/4 series the first 16-bit home computers. ==Features== The TI-99/4A's CPU, motherboard, and ROM cartridge ("Solid State Software") slot are 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, is 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 (a modified 13" Zenith color TV) as Texas Instruments could not get its RF modulator approved by the U.S. Federal Communications Commission in time . The TI-99/4A did ship with an RF modulator. 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 uses a variant of linear predictive coding 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 text-to-speech 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. The TI-99/4'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 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 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 power 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 which 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 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. 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 includes TI BASIC, a strict ANSI-compliant BASIC programming language interpreter which is 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 remove the ability for the system to execute unlicensed ROM-based cartridges, locking out third-party manufacturers such as Atarisoft.The system has a joystick port that supports two digital joysticks, which TI referred to as "wired remote controllers." The two joysticks are connected through a single nine pin DE-9 port which is identical with those used for Atari 2600 joysticks but with incompatible pins. Aftermarket adapters were available which allow the use of two Atari-compatible joysticks. The computer supports saving to, and loading from, two cassette drives through a dedicated port. Composite video and audio are output through another port on NTSC-based machines, and combine through 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Texas Instruments TI-99/4A」の詳細全文を読む スポンサード リンク
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