TI-99 sidecar expansion

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The TI-99 sidecar expansion components were originally released to provide expansion capability to the TI-99/4. Several expansion devices were designed, though not all were released commercially. At least one, the P-Code Peripheral, may be vapor ware. Each of the devices, with the exception of the Disk Controller, allows the bus to pass through to additional peripherals. TI rethought their expansion strategy when the FCC tightened RFI requirements at the beginning of 1982. The train of peripherals did not meet the requirements for an FCC Class B device, and so most of them were discontinued in favor of the PEB.

Speech Synthesizer

Refer to article on Speech

RS-232 Expansion

This peripheral adds a pair of RS-232C ports to the computer. No provision is made for parallel devices. It has its own power supply and can be placed anywhere in the peripheral chain after the Speech Synthesizer and before the Disk Controller.

32K Memory Expansion

This peripheral adds 32K of 8-bit CPU memory to the computer. It has its own power supply and can be placed anywhere in the peripheral chain after the Speech Synthesizer and before the Disk Controller. It requires specialized software to access it, as it is not recognized by TI BASIC. Several cartridges make use of the additional memory: TI Extended BASIC, TI Writer, TI Multiplan, Editor Assembler, Mini Memory, and both versions of TI LOGO (I and II).

HexBus Interface

The TI HexBus Interface was effectively the last peripheral device TI specifically developed for the TI-99/4A. Other items were in development at the same time, but they could be used with both the TI-99/4A and the TI-99/8. It added the capability to connect HexBus peripheral devices while allowing concurrent connection with a PEB. Unfortunately, TI withdrew from the home computer market before the device went into serial production, so only a few prototype devices survive. The HexBus Interface was eventually reverse-engineered by TI enthusiasts in Germany, though they also only produced a few of their HexBus Interface clones (the last count stood at three, though they were willing to produce more).

Single-Density Floppy Disk Controller

Catalogue PHP1800

This peripheral adds the capability to connect up to three Single-Sided, Single-Density (SSSD) disk drives to the computer. It has its own power supply and must always be the last peripheral in the peripheral expansion chain. The disk drives can be formatted as either 35 or 40 tracks of nine sectors each. As 35-track drives were no longer standard at the time it was released, all known disks used the 40-track format.

Video Controller

The Video Controller allowed connection of several models of videotape recorders and laser disk players to be connected to the TI-99/4A. It was designed to allow interactive instruction using a combination of computer software running on the machine and video instruction materials retrieved from the tape or laser disk as part of the lesson. The Video Controller was listed on TI price lists in 1981, but the device failed the necessary FCC certification, and so could not be sold to consumers. It could be used in industrial environments, but was apparently never put into production for that market. Only a few prototypes survive. It maintains full forward compatibility with the Video Controller Card for the PEB.

Thermal Printer


Catalogue PHP1900

The first printer that Texas Instruments made available for the TI99/4 was a 32 column thermal printer which attached to the right hand side port. In a daisy chain the printer had to be the last unit as there was no pass through.

Routines were built in to allow you to print screen graphics to the Thermal Printer. The character set was a 5x7 matrix.

The TI paper unfortunately suffered from fading.