yes, you need to bank-switch. * first, disable interrupts and keep them off * then send a specific byte to a specific IO port to see multiplan
* access the memory, etc * then send a specific byte to a specific IO port to get back to the main rom * enable interrupts IN 0D8h ani 00001100b ; keep the ram bits, zero out the rom bits ori 00000001b; enable multiplan rom OUT 0D8H IN 0D8h ani 00001100b ; keep the ram bits, zero out the rom rom bits OUT 0D8H think this should do it. On Thu, Jan 29, 2026 at 4:29 AM B 9 <[email protected]> wrote: > What with talk of uploading the ROMs from Model-T computers, I spent some > time learning how to implement a tiny CRC-16 checksum in machine language > (using the Xmodem polyomial and a seed of 0). It works great on the Model > 100 and 102. However, I just realized I have no idea how to read the entire > ROM from a Tandy 200. > > I've heard it said that the Tandy 200 has 72K of ROM. I believe 40K is > visible from BASIC and the other 32K is visible when Multiplan is launched. > > Does anyone know how I can read the Multiplan ROM from either BASIC or > assembly language? > > Thanks! > > —b9 >
