Resistor pack values for Compaticard IV

[ECNeilson]

A few years ago I acquired a Compaticard IV that that did not have the BIOS and other components populated on the board. I'm going to add the missing components, and I have everything I need except the two bus resistor arrays. Does anyone know what the resistor array values are for RP2 and RP3 (see pictures I snagged from the Internet)? The lettering on the part looks to be 10C9X2220, but I'm not translating that into a resistor value.




Thanks,
Eric

 

[Chuck(G)]

10 pin bussed 2.2K resistor network--the 10th pin is unused. See, for example Bourns 4310R101222 or Vishay CSC10A012K20GPA

 

[ECNeilson]

Thank

10 pin bussed 2.2K resistor network--the 10th pin is unused. See, for example Bourns 4310R101222 or Vishay CSC10A012K20GPA

Thank you so much! The parts are on order now. It should be a fun project.

 

[ECNeilson]

After completing the upgrades to the card, it looks like my Pentium-166 ISA/PCI PC may be too new for the Compaticard to work. I'm getting "Divide overflow" errors when I load the CC4DRV.SYS driver. Even going the norom route and loading the BIOS through CC4BIOS.SYS (the newer 1.06 version available online) does not give me a working disk controller.

If anyone has any ideas, please share. For now, I'm shelving my pretty Compaticard IV.

 

[Chuck(G)]

Try disabling the BIOS on it and see if ImagDisk will run it. There's a possibility that your system's primary controller isn't playing nice with the DMA 2 selection.

 

[ECNeilson]

I disabled the primary FDC and set the Compaticard IV as primary to remove any potential conflict with other disk controllers and still no success. I also tried different DMA and I/O address locations. I tested both with BIOS enabled and on-board BIOS disabled. No luck in any scenario. It's possible the parts upgrades are incompatible in some manner. I'll have to look for an older PC to test with in the future.

 

[Chuck(G)]

ImageDisk doesn't use the BIOS and lets you specify the port number, though I believe that the IRQ and DMA are fixed at 6 and 2, repsectively.

 

[jxm]

Maybe the GALs of the defeatured card do not provide select logic for the added components. This would be a simple way to thwart end user upgrades. You can use debug to dump/examine the cards EPROM to see if it's readable.

 

[Chuck(G)]

A few years ago, one of these depopulated cards crossed my desk and I added the missing components, like you. Never got it to work as a full-featured card--I never figured out why.

 

[ECNeilson]

ImageDisk doesn't use the BIOS and lets you specify the port number, though I believe that the IRQ and DMA are fixed at 6 and 2, repsectively.

I can access the disk controller directly using ImageDisk, but I really want to use the full functionality of the card.

@jxm I burned my own EEPROM and verified the contents are identical to the 1.05C .bin files available online.

@Chuck(G) It's possible maybe there is a trace or something in the PCB that prevents upgrades like this.

I wonder if using DOS 7.1 as my OS would cause any issues? I might try a bare bones DOS 6.3 install as a last ditch effort.

 

[jxm]

Did you verify the EPROM contents on the programmer or read the EPROM from the card when installed in the PC? If the GAL logic of the defeatured card does not provide the correct chip select logic the EPROM can not be read. If you know the address where the EPROM is mapped then using the dump command in debug.exe you can verify read access to the EPROM.

 

[Chuck(G)]

With or without the PROM BIOS extension, CC4BIOS.SYS should have provided the functionality.

 

[ECNeilson]

Did you verify the EPROM contents on the programmer or read the EPROM from the card when installed in the PC? If the GAL logic of the defeatured card does not provide the correct chip select logic the EPROM can not be read. If you know the address where the EPROM is mapped then using the dump command in debug.exe you can verify read access to the EPROM.

Great idea, thanks! I'll try this.

 

[ECNeilson]

I am not able to read the BIOS through Debug/Dump, so something is definitely up with the bus logic on the card. I don't see any missing or cut traces on the PCB compared to online photos. Next step would be a logic analyzer, or maybe I'll just wait for one to pop up on eBay...

 

[Chuck(G)]

I suspect the programming on one of the GALs is responsible.

 

[ECNeilson]

I suspect the programming on one of the GALs is responsible.

I think you're right. There are three GALs on the board, and the one just to the right of the BIOS looks to plug into the ISA pins.