Hi Steve, Where to begin...
First of all, you're talking about two different and separate ROMs and their sockets, the System ROM which runs the computer and provides the various built-in applications, and an Option ROM which, as the name suggests, adds one or more optional programs or features. They are both 28-pin 32KB (256Kb) chips, so your 32-pin 128KB 27C010 chips will not fit without major adaptation. As you (re)discovered regarding North American models, early M100s (prior to late 1983) used a non-standard pinout while later M100s and the T102, T200 etc. used standard 27C256-compatible ROMs; the change seems to have been made somewhere between serial numbers 309xxxxxx and 401xxxxxx. If you want to replace an early M100 System ROM you will have to make or buy an adapter; a fellow list member just built some using this board: https://www.oshpark.com/shared_projects/Kil9S1ya Replacing a later model M100 System ROM is just a matter of plugging it in, but in the T102 it is soldered to the board and would require unsoldering the original ROM. The Option ROMs use a completely different socket arrangement, a Molex IC 'carrier' with non-standard pinout but you can use the adapter above which lets you combine the System and Option ROM in one chip that plugs into the System ROM socket (old or new). At one time there was an adapter available from several sources that would let you put an OTP (not re-programmable) EPROM into the option ROM socket but they seem to not be available any longer. Most people use Steve Adolph's REX module, which lets you put several different ROM images into one flash memory and I believe the later versions also permit changing the System ROM; see: http://bitchin100.com/wiki/index.php?title=Rex Another very useful add-on is/was the NADSbox but I believe they're no longer available unless you find a used one; a newer version may or may not become available in the future. Can't really give you a step-by-step since I don't know exactly what you want to do with/to what. Good luck! m ----- Original Message ----- From: Steven Ranft To: Club 100 Model T Sent: Monday, May 09, 2016 11:32 AM Subject: [M100] ROM burning questions I am pretty new to retro computing. But have become an addict in the last year or so. I have Several M-100, M-102, M-200, NEC-8201 and NEC-8300 systems in working order. I also have a ROM Booster PAC. I really have only scratched the surface of learning to use these machines. I bought some "D43256AC-10L" chips and increased the Ram to 32 K on the ones I could. I managed to get Virtual T running on my Windows 7 desktop. I built a cable, and can connect and transfer files to and from a laptop running DOS via desklink I also bought a Tandy floppy drive and got that working too. I haven't yet tried to use the BoosterPAK I did buy a e-prom burner (USB MiniPro TL866CS Universal BIOS Programmer) and some blank e-proms (27C010-12), but HAD come to the conclusion that the M100s will not accept Standard ROMs. I found a file named What ROM.txt (... AND NOW know that was not accurate) it has a section like this: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Board Code ROM type ROM Code Comment ============================================================================== PLX110CH1X custom LH535618 early North America PLX110EH1X 27C256 compatible 3256C07-3J1 late North America PLX120CH1X 27C256 compatible 3256C05-3E1 European/Italian I did a quick survey of serial numbers vs. PCB code and here are the results. Generally, later serial numbers use the 27C256 compatible board. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I forgot about this information and just found it again. I have 102s and a 200 to try, and probably several of 5 M-100s. I am tempted to try to burn SARDOS and try to plug it in. I know i need to run a BASIC command to "jump to an address" to get it to use the new ROM. Does anybody know if there is a step by step "How to guide" for what I am going to attempt and if not, do you have any words of wisdom or warnings? I am pretty sure the "27C010-12" are "27C256" compatible chips or will find some, and I know to check the serial number list and that there are different versions of SARDOS for the various flavors of Model-T. Anything I am missing? I hope to create a document to guide other neophyte Model-T'ers through this an post it on the repository if I get through it! Thanks, Steve Ranft Savage, MN
