FlashROM99
FlashROM99
Produced in 2016, FlashROM99 was a circuit board designed by Ralph Benzinger which plugged into the cartridge slot on a TI99/4a, and allowed an SDHC memory card to be plugged into it allowing access to up to 171 different modules stored in the SDHC card. Different cards could be inserted so that the 171 limit was not an issue.
A user able to download files and transfer them to the root directory of an SDHC card was able to make an immediate start with no greater knowledge or skill.
To begin, copy up to 171 cartridge image files onto an SD or SDHC card. Switch off the TI 99 and plug in the FlashROM 99, then insert the SD card into the FlashROM 99. Switch on the TI 99 and wait until the activity indicator on the FlashROM 99 is no longer lit.Press any key to bring up the TI menu screen.
Some module dumps made for other purposes could be used but some required modification (a simple inversion using a Python script) and multi-file modules required the parts to be concatenated. A few modules could not operate with the board due to size or various bank switching approaches. The board will not run any Extended Basic but makes available some other languages, although the various forths still require a disk system.
A good collection of the required module images can be found on ftp://ftp.whtech.com/Cartridges/FlashROM99/. These include some newer programs such as Flappy Bird.
The board contained a 32M RAM which permitted module images to run in their normal address space.
Although there is no GRAM in the design, module files modified to run from disk with Editor Assembler loader option 5 (eg program format) could be modified to work with FlashROM99 and stored on the SDHC card, no longer requiring a disk drive - but as they require to work in the address space of the TI 32k ram expansion, that expansion ram must be available for the FlashRAM99 to move the code into.
An initial design incorporated a capacitor/resister on the right hand side of the board which caused difficulties for disk access when using a TI disk controller. Subsequent removal of the 1nF capacitor solved this problem.
The board contains an LED which lit to indicate BUSY or used a flash code to communicate some errors (eg bad SDHC card) (Do nothing until the LED goes out!) and a reset switch which reloaded the menu and reset on board memory. The instruction was to only use the module reset switch when the TI99/4a master title screen was displayed.
The project was fully described on https://endlos99.github.io/flashrom99/
The board could be fitted into an old TI99/4a Romox module, or 3d printed modules were being produced.
A subsequent project FinalGROM used emulated grom and a modified file structure allowing over 171 images per card, but was compatible with the cartridge image files used by FlashROM.