My father had one of these advanced TI-99/4A compatible computers that was late to a very small market. It was so much faster than a 4A and it had 80 column text, and the same graphics capabilities as the MSX2.
There are ‘GENMOD’ version of the Geneve with a 2 megabyte MEMEX expansion card. This allows the Geneve to use a full 2 megs of 0 waitstate memory, making it even faster in its native mode of operation.
I had possession of one for a period. Knowledge of how to build the Turbo + TIMode switch box seemed to be missing.
I’ve heard of 2 other GENMOD Geneves in the US that are still operational, and both of those in possesion do not have the switch-box that came with the upgrade. The switch box is necessary to get maximum speed by using 0 wait state memory for all of the system ram. Otherwise, it defaults to TIMODE where the onboard wait state generator is used.
The switch box just has 4 components in it:
- 2 LED(red)
- 2 SPST(NO)
- 4 wires
- 4 Dupont connectors
There is usually a connector on the back of the modified Geneve 2.54mm spaced, 4 pins. I will refer to them with the top pin as pin 1 (matching the labelling on my connector), and the bottom pin as pin 4.
When the “TURBO” switch is in the off position, then turbo mode is active on the Geneve (0-wait state memory access)
When the “TI-MODE” switch is in the off position, then the 512k memory on the Geneve is used with wait states instead of memory on the MEMEX card (1.5meg of the memex can still be used at 0-wait state)
- pin1 - to positive lead on TI-MODE LED
- pin2 - (ground) to negative lead on TI-MODE & TURBO LED, as well as one terminal of each switch
- pin3 - remaining contact of TI-MODE switch
- pin4 - remaining contact of TURBO switch & positive lead of TURBO LED