General Category > Lisa Troubleshooting and Repair
Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
AlexTheCat123:
Is there a utility that will convert a DC42 image of a ProFile to a BLU image that I could transfer over to my ProFile? Since the floppy drive still isn't working, I was thinking about trying to install LOS in LisaEm, converting the resulting ProFile image to BLU format, and then sending it over to my Lisa, but I can't find a utility that will convert from DC42 format to BLU format.
rayarachelian:
--- Quote from: AlexTheCat123 on June 11, 2021, 10:20:51 am ---Is there a utility that will convert a DC42 image of a ProFile to a BLU image that I could transfer over to my ProFile? Since the floppy drive still isn't working, I was thinking about trying to install LOS in LisaEm, converting the resulting ProFile image to BLU format, and then sending it over to my Lisa, but I can't find a utility that will convert from DC42 format to BLU format.
--- End quote ---
This might work: https://github.com/rayarachelian/lisaem/blob/unstable/src/tools/src/raw-to-dc42.c if not let me know and I'll add an explicit dc42-to-blu command - not sure if BLU checks for the BLU signature or not. BLU is the same format as raw, but with the ffffff block first and in there it has a BLU version #
Easiest way to build this is to build the unstable branch of LisaEm.
AlexTheCat123:
The 6504 finally came in the mail and after putting it in, the floppy controller seems to be working slightly more than it was before, but it's definitely still broken. I don't get the error 57 anymore and the I/O ROM version is no longer FF, but the version is only reported as A8 every five or six times that I look at its memory address in service mode. Other times, it's seemingly random values. Sometimes, the Lisa lists two floppy drives in the Startup From... menu and other times it just lists one, so clearly something isn't right. It sometimes just hangs and sometimes gives error 39 (drive ROM can't keep up) when I try to boot from the floppy drive and BLU always gives floppy errors whenever I start it up. What should I try next?
rayarachelian:
--- Quote from: AlexTheCat123 on June 15, 2021, 11:06:21 am ---The 6504 finally came in the mail and after putting it in, the floppy controller seems to be working slightly more than it was before, but it's definitely still broken. I don't get the error 57 anymore and the I/O ROM version is no longer FF, but the version is only reported as A8 every five or six times that I look at its memory address in service mode. Other times, it's seemingly random values. Sometimes, the Lisa lists two floppy drives in the Startup From... menu and other times it just lists one, so clearly something isn't right. It sometimes just hangs and sometimes gives error 39 (drive ROM can't keep up) when I try to boot from the floppy drive and BLU always gives floppy errors whenever I start it up. What should I try next?
--- End quote ---
So either there's something wrong between the I/O board bus pins and the CPU board (i.e. motherboard connector) or the SRAM on the floppy controller is broken.
On initialization, the 6504 will write it's version to the shared SRAM. It will do this only once.
So if that value fluctuates, something is wrong either at the bus level (and we've seen this before with your Lisa) or at the SRAM level.
You can swap out the SRAM to be able to tell which.
One thing you could look at is to see the values that show up that are not A8 and map those in binary. This will tell you which bits are either broken in the SRAM or on the bus.
Another thing you could do is piggy back a second identical SRAM chip on top of the existing one. If the problem goes away that might indicate the SRAM.
However, if the existing SRAM is bad and reports "1" values where it should be "0", the 2nd SRAM will not help.
There's a tiny bit of danger to this since you're connecting two outputs together, but it's very small. Worst case you'll cause the new SRAM to burn out as well, but I don't think these are so expensive that it matters that much.
If the randomness issue doesn't go away, it's still either the SRAM or the bus.
If you have a large logic analyzer it may help you debug futher. i.e. the old Agilent/HP ones that you could interface directly to a chip. @Sigma7 introduced me to these early on in the days of LisaEm, but it turned out I didn't need to break out this big gun to work on LisaEm, and indeed I needed very little actual testing on a real Lisa in 99.999% of cases. So I'm not very well versed in how to use such test equipment. However, in this case, if you own one and have it handy it could immediately help you diagnose the issue.
All this said, the amount of time it will take you to diagnose, it might just be quicker to desolder to SRAM, solder in a socket, and then insert a new SRAM. If the problem goes away, you're done in ~30 mins. If it doesn't, you know exactly where to look next. (Well maybe some lines from the area on the I/O board where the SRAM and the logic gates that enable it to be visible to the 68000 - DISKDIAG?, to the fingers on the I/O board, to the motherboard connector, to the traces on the motherboard, to the CPU board connector, to the CPU board itself.
AlexTheCat123:
I just wrote a simple Arduino program that will test these RAM chips by writing every possible value to each address and then reading the value back and both chips passed just fine. I guess this means that it's a bus issue, which will not be very fun to troubleshoot :(.
--- Quote ---If you have a large logic analyzer it may help you debug futher
--- End quote ---
I have a USB logic analyzer, but the vast amount of data that it produces when connected to the Lisa makes it impossible to go through it all. The text and CSV files that it outputs are so large that I can't open them in any program without it crashing.
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