Greetings to all at Vogons! I was recently granted an account, and seeing as I've done very little with forum sites, I'll be sure to make some mistakes, but here we go. I had a few questions on burning an Eprom for a 386 Motherboard. I haven't burned a prom since I did so (at work) on a Zenith CP/M computer back in the mid-eighties. The 386 motherboard is a replacement board purchased recently to replace one I was using that got killed with voluminous battery leakage. So, after skimming thru Vogons, Stason & Win3X, the replacement board would seem to be a generic clone of a "Shuttle HOT 307" (or the HOT 307 is a clone of whatever I've got). When I got to testing the unit, the initial result was really depressing- Nothing happened. No beeps, no computer activity at all other than that of the power supply. After a few moments stewing about what I could be doing wrong, it occurred to me that the board may not recognize the Ram present in bank 1 until bank 0 was filled. So, relocating the Ram to bank 0 produced.... JOY... the computer and screen came to life, and I was able to get into the bios. (Theres something fabulous about that monitor LED going from yellow to green to let you know the MBD and graphics card are at least alive, Yes?) Joy turned to cautious optimism, however, when along the way a message appeared "RAM pattern test failed at 0C0000H". Further cold water was thrown when although the memory base was reported to be 640K, the extended Ram and system Ram sizes were reported by the bios as 0K (that's zero Kbytes, not ooh-kay). That was not good. I had equipped the board with 4 megs of memory, so where was the rest? The board did allow the working of DOS, however, so it seems the functionality of the board was there. Since the board had been in storage for a long time, it could not hurt to reseat the processor, the memory sticks, the bios chip, and the two chips I read are the "Tag" chips. So, that's what I did (VERY carefully). Next power up, No change. I could not miss, however, that the pins on the bios chip had that telltale bend towards one end that indicated the bios chip had been not-to-carefully pulled out previously. Hmmm. The bios screen has on it "Opti 306". The board indeed has an OPTi chipset, but there are no 306 anythings. My suspicions now hang over the bios chip and I want to burn an Eprom to the image that user Skyscraper uploaded a few years ago for the Shuttle HOT 307. As of June 1 2021, I had no burner, no UV eraser, and no chips but all were ordered. Now later at 6/12/2021 - I got hold of a couple chips, a burner and a UV eraser, the burner being the Autoelectric.cn / Xgecu TI866 II Plus.
My first questions are, why do you need to fill an eprom completely? And what do you fill the rest with? A Vogons forum entry suggested theres a reason to fill it with additional copies of the bios hex file. As to why you need to fully fill the chip, I get from reading various entries that there's some sort of parity check failure if you don't fill the chip. As for an Eprom fill, from a Vogons entry of 2016-08-19, user Jesolo wanted to repair one MBD and upgrade another by giving them modified Eproms, and received the caution from user Keropi that he needed to fill the rest of the 64K image before burning it into the Eprom. The quote being : "For 386 and 486 mobos though you'll be fine with the W27C512s Jesolo - just keep in mind to fill the whole 64kbytes in case a 386 BIOS is only 32kB and was using originally a 27C256."
Third question - Nowhere in the step-by-step directions of the burner device's lit does it tell you when it's safe to put the chip into the socket of the burner. It would make sense to be at least when the thing has been powered up and after you've selected the device in the burner's devices list. Having the chip installed when you power up seems like a bad idea. Maybe someone has been successful at finding this info.
I'll be checking up on this site only on weekends and during the week only past 6:00 due to time limitations. Thats it for now.