Hi Chesh,
Good progress, looks like the RESET is now working fine and you have now proven the RAM is all OK.
A) I have never used the BN55 myself and have no idea if that maybe a contributing factor.
Personally I would stick with either BN54 or BN56 for this system.
Is your BN55 boot ROM a CMOS variety? I have had some issues with the CMOS ones on this Coreboard in the past some makes are more of a problem than others. If it is a CMOS one, try burning the into a none CMOS EPROM and see if that works? I have a spare BN56 if you want to give that a go.
If you can’t jump into the Monitor with the M key held down during boot-up then it seams like the initialisation routines for the 6545 is not happening so there is no keyboard scanning.
Try getting into the monitor you could try removing your FDC 2793 chip and the system should then boot straight into the Monitor. But that may not work either if the 6545 is not getting initialised at all to see any screen output.
At this point I would be putting my money on you having a CMOS EPROM problem.
Does the Coreboard have a set of resistors in series with the Data lines coming in on Pins 18 - 25 of X1?
I have done this MOD on all my MB8342 Coreboards with SMD resistors.
Ernest
Good progress, looks like the RESET is now working fine and you have now proven the RAM is all OK.
A) I have never used the BN55 myself and have no idea if that maybe a contributing factor.
Personally I would stick with either BN54 or BN56 for this system.
Is your BN55 boot ROM a CMOS variety? I have had some issues with the CMOS ones on this Coreboard in the past some makes are more of a problem than others. If it is a CMOS one, try burning the into a none CMOS EPROM and see if that works? I have a spare BN56 if you want to give that a go.
If you can’t jump into the Monitor with the M key held down during boot-up then it seams like the initialisation routines for the 6545 is not happening so there is no keyboard scanning.
Try getting into the monitor you could try removing your FDC 2793 chip and the system should then boot straight into the Monitor. But that may not work either if the 6545 is not getting initialised at all to see any screen output.
At this point I would be putting my money on you having a CMOS EPROM problem.
Does the Coreboard have a set of resistors in series with the Data lines coming in on Pins 18 - 25 of X1?
I have done this MOD on all my MB8342 Coreboards with SMD resistors.
Ernest