FlexROM 200: Difference between revisions
(Created page with "Work in progress. NOT YET TESTED - PROCEED AT OWN RISK Like FlexROM_102 but for TANDY Model 200. Adapter boards to replace the main system ROMs in a TANDY 200 with a re-...") |
|||
| (2 intermediate revisions by the same user not shown) | |||
| Line 18: | Line 18: | ||
For Model 200, it's a little more complicated, because there are two chips to replace, and one of those is weird and needs an adapter with extra parts | For Model 200, it's a little more complicated, because there are two chips to replace, and one of those is weird and needs an adapter with extra parts | ||
For the 32K M15 chip | ==For the 32K M15 chip== | ||
The original chip is standard and you only need a [[FlexROM_102]], and connect it the same way as for 102, /CS_BUS goes to TP1 on the REX. | |||
Follow all the FlexROM_102 directions for programming, installing, connecting to REX. | |||
To program the | ==For the 8K M13 chip== | ||
This adapter exists but is not yet tested: [https://github.com/bkw777/aDIPters#flexrom_200_m13 FlexROM_200_M13]<br> | |||
BOM: https://www.digikey.com/short/q3zm9cf4<br> | |||
To program the M13 board:<br> | |||
set the small jumper to the PGM position<br> | set the small jumper to the PGM position<br> | ||
jumper /OE_BUS to /OE_IC<br> | jumper /OE_BUS to /OE_IC<br> | ||
| Line 32: | Line 37: | ||
otherwise jumper to /OE_IC | otherwise jumper to /OE_IC | ||
install board in position M13 on TANDY 200 motherboard | install board in position M13 on TANDY 200 motherboard | ||
Like the directions for FlexROM_102 show, also run a 2nd dupont jumper wire from /OE_IC out to the option rom bay but don't connect it to anything. Label it "M13_IC". To remove REX and revert to booting from the internal roms, remove the M13 wire from the REX TP2 and connect it to the M13_IC wire. | |||
Latest revision as of 01:08, 11 January 2023
Work in progress. NOT YET TESTED - PROCEED AT OWN RISK
Like FlexROM_102 but for TANDY Model 200.
Adapter boards to replace the main system ROMs in a TANDY 200 with a re-writable EEPROM or FRAM or FLASH, and provide revertable connections for use with the Main ROM feature of the REX_Classic.
The Model 200 needs two chips replaced in positions M15 and M13, each with their own chip-enable wires connected to the REX.
The original directions just say to remove the original ROM chips and install a couple of wires from the empty sockets to the REX.
With that setup, the machine can no longer run without the REX.
The goal here is to provide a way to use the REX main-rom feature while still leaving viable roms installed in the original sockets, inactive while REX is installed, but able to be re-activated without opening the case again. So the REX could be removed, or scrambled by installing a bad rom image, and the machine can boot from the internal roms.
For Model 100 and 102 this is fairly simple.
For Model 200, it's a little more complicated, because there are two chips to replace, and one of those is weird and needs an adapter with extra parts
For the 32K M15 chip
The original chip is standard and you only need a FlexROM_102, and connect it the same way as for 102, /CS_BUS goes to TP1 on the REX.
Follow all the FlexROM_102 directions for programming, installing, connecting to REX.
For the 8K M13 chip
This adapter exists but is not yet tested: FlexROM_200_M13
BOM: https://www.digikey.com/short/q3zm9cf4
To program the M13 board:
set the small jumper to the PGM position
jumper /OE_BUS to /OE_IC
place the board into a programmer
To install:
set the small jumper to the RUN position
If using REX main-rom feature: connect /OE_BUS to TP2 on the REX
otherwise jumper to /OE_IC
install board in position M13 on TANDY 200 motherboard
Like the directions for FlexROM_102 show, also run a 2nd dupont jumper wire from /OE_IC out to the option rom bay but don't connect it to anything. Label it "M13_IC". To remove REX and revert to booting from the internal roms, remove the M13 wire from the REX TP2 and connect it to the M13_IC wire.