Random crashes on boot.

[chriskgnr]

Hello.
A few weeks ago, i repaired a QL with a dram ic issue by replacing one 4164. From then, i get a few random crashes on boot. I installed the Minerva 1.98 OS, but i don't get any ram errors on boot. What i spotted is when i press the reset button i get a white stripe in the middle of the screen, which i haven't see it on any other QL. The second peculiar thing is that when i format a microdrive cartridge i get a "NUL" as the photos show. Does anybody knows what is going on ?

[lliont]

I think the line is ok on systems with Minerva.

[jobdone]

not really an answer, but the 'nul' is telling you the mdv has been formatted with a name of chr$(0).

[Chr$]

I've seen the NUL things for carts before. I think it's the default name given to a cart when formatted without a name and with a certain ROM version (no idea which)... or perhaps the cart name that is read when formatted with no name and with a different ROM version to that currently in use. Can't remember, but definitely seen it before and I don't think it's significant.

[Martin_Head]

I don't know if you've sorted the crashing problem out yet. But just a thought.

Is the speed rating on the RAM chip you replaced the same as the others?

I'm thinking, if it's faster/slower than the others. Maybe there is a timing problem that just shows up during booting.

Have you tried changing the RAM chip for another one, or one from another manufacturer.

I'm assuming that the QL was working OK before the RAM failure.

[chriskgnr]

Hello again. As @lliont stated, the white line occured only with the Minerva firmware. When i switched to JM the white line disappeard. As for the dram ic, i replaced a TMS4164-15NL with a TMS4164-12NL and i think that is ok.

[tofro]

On startup, the QL video circuitry just shows the random values that happen to be in the DRAM chips for video memory.

These random values might just be different for your new DRAM - if Minerva's memory test passes, I wouldn't bother.

(This does, however, absolutely not explain why you do not see the same stripes with a JM ROM - while the random pattern is shown, the ROM and CPU mostly haven't done anything yet. The only explanation for that could be different electrical characteristics of that ROM (i.e., not the contents) that happen to influence the bus, and thus the random pattern)

[chriskgnr]

(This does, however, absolutely not explain why you do not see the same stripes with a JM ROM - while the random pattern is shown, the ROM and CPU mostly haven't done anything yet. The only explanation for that could be different electrical characteristics of that ROM (i.e., not the contents) that happen to influence the bus, and thus the random pattern)

I believe this is the best explanation.