A 27C512 has the identical pin configuration as a 27C256 with the exception of pin 1. Pin 1 is used to access the upper 32k or the ROM.
On the system board, U11 is the chip of interest. Here is what happens when you go from bank 1 to 2 and to 3. 10 15 0 0 = Bank 1 0 1 = Bank 2 1 1 = Bank 3 If you tie pin 1 of the 27C512 to pin 15 of U11, then when you switch banks, you switch ROMs. I have two machines wired this way. My third machine has my REX in it because it's far easier to test ROM images with REX than to burn them to a ROM. Kurt On Wed, Mar 11, 2020, at 10:38 AM, Josh Malone wrote: > Details! This sounds great. I didn't realize that REXNEC (or whatever it's > called) was still being built, so I haven't REXed up my NEC. > > On Wed, Mar 11, 2020 at 1:30 PM Kurt McCullum <ku...@fastmail.com> wrote: >> __ >> Speaking of standard ROMS, a 27C512 can be burned with SARDOS on the lower >> 32k and UR-II on the upper 32k. Then pin one wired to a pin on the system >> board. This allows for bank 1 to have SARDOS and bank 2 to have UR-II. I >> have a couple of mine setup this way. >> >> On Wed, Mar 11, 2020, at 10:23 AM, Josh Malone wrote: >>> The 8201a can take a standard 27C256, so you can drop in a 'SARDOS' ROM or >>> some such. If you want one, I can burn it for you (I might have 1 or 2 >>> already made up from Tandy Assmebly). Contact me off-list >>> >>> On Wed, Mar 11, 2020 at 1:20 PM Jason Benson <jason.benson...@gmail.com> >>> wrote: >>>> Is there a loader for NEC TSDOS? My 8201A doesn't have an option rom, but >>>> I can transfer DO files to it from my M100. >>>> >>>> On Wed, Mar 11, 2020 at 12:33 AM B4 Me100 <b4me...@hotmail.com> wrote: >>>>> The attached file will generate TSLOAD. Quite a small Basic program that >>>>> loads the file into memory, the .do file can be deleted after loading. >>>>> >>>>> On 10/3/20, 8:47 PM, "M100 on behalf of Joshua O'Keefe" >>>>> <m100-boun...@lists.bitchin100.com on behalf of maj...@nachomountain.com> >>>>> wrote: >>>>> >>>>> >On Mar 10, 2020, at 8:39 PM, Kurt McCullum <ku...@fastmail.com> wrote: >>>>> >> TS-DOS and Sardine for UR-II attached >>>>> > >>>>> >Thanks for this. For those of us with optionless hardware you wouldn't >>>>> >happen to have the loader handy as well, would you? I think it's called >>>>> >TSLOAD? Ive been keeping DOS100 itself in RAM and it's kind of hefty. >>>>> >Using the loader seems more memory-friendly, but I have yet to figure out >>>>> >where to find a copy. >>>>> >>
