Hi everyone,

another day, another board and some issues. I got this board for a few bucks but did not noticed how much the traces on the board were attacked by the battery, however, I have found just one that was really broken and checked the continuity on the rest of them around the battery and the KB controller. After turning the board for the first time it did not post or anything but the KB controller got extremely hot. I took it out (https://www.ebay.com/itm/255916972193 - this one was the original) and replaced by another 8042. Then I have found some jumper issues, etc... took some time to post but eventually the board started to post. However, it is in a "boot loop".

The reference for the board is here: https://theretroweb.com/motherboards/s/shuttl … 9-ver.-2.2#docs, however, feeding the RAM to BANK 0 according to the jumper setting manual will cause CODE 1312 on the post card and 3-short beeps. It seems like a RAM problem, feeding the RAM to BANK 1 - again according to the manual at RetroWeb, the board stops to claim about the RAM and post further, however, after reaching the CODE 5523 it will start over in a loop, every time stopping at CODE 5523 - no beep. There is no CODE for 55 but 23 refers to Reading the 8042 input port .... Different 8042 will result in the same issue, no difference.

Strange thing which I do not understand is how the clock generator behaves. For 40MHz CPU it is set to 80MHz, the CLK on the socket is however 40MHz - can anyone explain this? The CLK on the ISA slot is 8MHz.
Another strange thing is the OSC between the ISA slots, between the 1 and 2 ISA slot. It outputs 64... kHz, I would be expecting 32... kHz, how is this possible? The OSC gives the frequency only at one leg, the second one is dead, no voltage, no signal. Measuring the resistivity to GND of this leg gives me nothing, not a short, just no connection.

My questions now are:
- Why the former 8042 went to short? and if this could result in more damage of course that I do not see. Any idea?
- Why the CLK generator outputs 80MHz but on the CPU CLK I do have 40MHz, how this works?
- Is the behaviour of the OSC that should, I guess, outputs 32kHz output 64kHz, does the dead second leg could indicate something?

A few days ago I would be de-soldering stuff already but decided to ask first for your opinion.

best regards, Tomas