Thanks! Where is that documented? I was getting lost looking at the T200's Technical Reference which was way too low level (there was a diagram for the banks, but it showed setting AD0, AD1, AD2 while asserting WR and Y, or some such silliness).
--b9 On January 29, 2026 5:13:03 AM PST, Stephen Adolph <[email protected]> wrote: >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 >>
