Questions tagged [ti-99]

For questions about the Texas Instruments TI-99 series of micro-computers, in particular the TI-99/4A.

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17
votes
4answers
3k views

Why did the TI-99/4 have two databuses?

Wikipedia says on Russian page: Однако к 16-разрядной шине были подключены только 256 байт статической памяти и системное ПЗУ. Остальная память (ОЗУ) и периферийные устройства были 8-разрядными и ...
10
votes
2answers
1k views

How to fix a TI99/4a membrane keyboard?

I recently purchased a 1982 TI99/4a that has a defective keyboard. The keyboard is a Mitsumi with normal keys, but membrane type contacts. When I press the contacts (gently) with a plastic stylus ...
9
votes
2answers
1k views

Is it possible to use a TI-99/4A cassette cable with Digital Audio devices?

I would like to save and load BASIC programs with my TI-99/4A. The TI-99/4A can be connected to a cassette recorder for this purpose. Buying a cassette recorder and cassette tapes seems unnecessary ...
4
votes
1answer
762 views

What was the purpose of GROM (vs ROM) in the TI-99/4a?

The TI-99/4a had a cartridge slot on the front of the computer which accepted "solid state cartridges" (as TI called them). These cartridges would typically contain ROM (Read Only Memory) like many ...
4
votes
1answer
323 views

Why did Extended BASIC on the TI-99/4A only allow 28 of the 32 sprites?

The Video Display Processor (VDP) of the TI-99/4A was capable of displaying 32 hardware sprites. These sprites were unusable with the default, built-in BASIC that TI provided. However, an enhanced ...
2
votes
0answers
120 views

How many units did TI Invaders sell?

I'm trying to get a feel for the scale and dynamics of the early home computer game industry. Statistics for arcade games and console cartridges are relatively easy to come by, e.g. that Pac-Man on ...