Timex Computer 2068 upgrades
DOCK cartridges and /ROMCS on edge
The /ROMCS on edge slot is in fact the ROMDIS signal as
in ZX Spectrum and disables both 68 ROM (HOME and EXROM)
and HOME ROM cartridges. But doesn't disable DOCK
memory, what can cause memory conflicts.
The solution is to use 151 demultiplexer with the input
selected with A14, A15 and /ROSCS. And provide the not
inverted output to /ROSCS pin of cartridge slot.
| /ROSCS | A15 | A14 | Input |
|---|
| 0 | 0 | 0 | ROMDIS (/ROMCS on edge) |
| 0 | 0 | 1 | 0 (low) |
| 0 | 1 | 0 | 0 (low) |
| 0 | 1 | 1 | 0 (low) |
| 1 | 0 | 0 | 1 (high) |
| 1 | 0 | 1 | 1 (high) |
| 1 | 1 | 0 | 1 (high) |
| 1 | 1 | 1 | 1 (high) |
See also
- Timex Computer 2068
- Timex Computer 2068.
- Unipolbrit Komputer 2086
- Unipolbrit Komputer 2086. Polish version of Timex Computer 2068.
| | CPC
Sam Coupé
MSX
Spectrum
Timex
Timex FDD
ZX81
|