magicvoodooable wrote on 2022-08-09, 23:52:At a second look it appears the 1st 64KB are the Video BIOS of the on-board Cirrus Logic VGA controller and the System BIOS itse […]
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At a second look it appears the 1st 64KB are the Video BIOS of the on-board Cirrus Logic VGA controller and the System BIOS itself is in 2nd half.
Attached is my BIOS dump.
As far as I can tell it look OK but would appreciate a second opinion. I really don't understand my my board doesn't even beep, i.e. memory error, etc. it's like life-less.
I checked all the voltages, tried different jumper configs for the CPU configuration, installed/removed RAM, disabled the on-board VGA.
CPU gets warm and has proper 33 MHz clock on its clock pin. I triple checked now for broken traces due to battery damage and at this point I'm pretty sure I got them all repaired.
Seems to me I'm the only one that has problems getting this board even to show any form of life 🙁
Hi magicvoodooable,
About the BIOS for this board, your BIOS dump looks OK to me as well. These AMI BIOSes use a Little-Endian 16-bit checksum on the BIOS core, the upper 64KB part of the 128KB dump. When I let my hexeditor do this calculation, it comes up with the correct 16-bit outcome of zero.
I also tried your TMS27PC010A dump on 86Box and got a hang and bootloop at POST code D4h. This is exactly as expected and I got the same on another AMI WinBIOS for the PCChips M912 which uses the same UMC8498 chipset.
POST D4h occurs very early during POST and is where the BIOS jumps to code in Shadow RAM after the BIOS ROM is decompressed and copied there. As 86Box doesn’t know the UMC8498 chipset, it can’t control Shadow RAM and the jump at POST D4h will end up in oblivion. 😉
But your BIOS dump runs and produces POST codes and has a correct checksum. So I’m convinced it is sound and that your board must have a hardware problem…
@nathanieltolbert: Your BIOS dump is only 64KB and is missing the Video BIOS for the onboard VGA chip. Also the checksum is incorrect, so I’m afraid it is a corrupt BIOS. 🙁
I believe it is a decompressed Shadow RAM copy of the upper 64KB of the original BIOS and can’t be used to put in an EPROM. Maybe a good idea to have it pulled from The Retro Web. 😉
Can you make a full 128KB dump from your EPROM chip with an EPROM programmer, so I can compare it with magicvoodooble’s BIOS?
Cheers, Jan