Hi all,
After replacing the ROMs (document to come soon), I got on to the RAM.
Replaced all 91L24 chips with 2x HM62256B (that's all I had at hand), thinking to first try out the simple SRAM and then, if all OK, to move over to NVSRAM like DS1230.
First boot with the new chips went fine, but then, to my surprise, from the second boot on, it bypassed the self-check routines, booting (seem correctly) directly into the scope mode. Quickly digitized a wave and display it. All good. Powered off and then on again...
...It booted directly in the "stored" mode with the right wave displayed.
I can assure you that the first impulse was to check if the battery backup is present. The second was to see if, by mistake, I did not inserted the NVRAM chips instead. None of this was true. It must be some energy stored in the caps. Tested some more and got to fully discharge in about 3-4 minutes, when it boots with the self-check.
One question, before proceeding further: is it normal to bypass the self-check if the contents of the RAM is still present, like when the backup battery is present? I find this a little weird.
Sorry for the long post and thank you inadvance!
Bogdan
