*** M E M O R U M ***

I've tried piggy-backing another 74LS08 on the top of 7E and it SEEMS to be better, as in I can run chess... for a while... until something warms up. Then it becomes unstable.

I'll swap that chip anyway as it's the last one in the whole memory addressing sub-system I've not changed.

Dave wrote: ↑16 May 2019 23:40 It’s easy enough to create an eye by looping a bit of bared wire and soldering it, without letting the hole fill with solder

I found a PDU earthing wire at work with an eye at the end. It's a bit of an overkill in terms of wire thickness but it's fitted.

I s'pose it could be a RAM paging issue... I ran Toado from SDX BASIC, immediately reset into CP/M mode and when CP/M crashed the game loop of TOADO started, with the logs going across the screen and the "fly" appearing and disappearing and the sounds being produced. Other than the CPU, PA...

Do you have a wire connecting the regulator bolt to the ground terminals on the AV connector? I didn’t see one in your photos. Again, probably nothing to do with the current (but hopefully fixed) problem but if it’s not there it can give display problems You can see it in this photo http://www.prim...

Bother! Spoke too soon. It's back to its old ways.

I think that I've possibly found the problem: (a) The lower case is somehow not being earthed by the screw-bolt going through the heatsink. (b) The TV is sending a 50Hz, 50V (very low power) noise down both the TV or composite video connection. (c) The CFX data signals are only marginally above the ...

I wonder if there might be a problem with the DRAM timing circuit? Assuming that all the chips in the circuit are working, it might be worth checking C5 and C6 for damage. With all the work on the machine, they might have taken a knock? I had a weird RAM fault that turned out to be a cracked capaci...

I wonder if there might be a problem with the DRAM timing circuit? Assuming that all the chips in the circuit are working, it might be worth checking C5 and C6 for damage. With all the work on the machine, they might have taken a knock? I had a weird RAM fault that turned out to be a cracked capaci...

I wonder if there might be a problem with the DRAM timing circuit? Assuming that all the chips in the circuit are working, it might be worth checking C5 and C6 for damage. With all the work on the machine, they might have taken a knock? I had a weird RAM fault that turned out to be a cracked capaci...

These are all from Farnell. Anyway, things have got interesting... Replacing the CPU with one of the scavenged Z80Bs I friend gave me and CP/M was a little bit more stable. Key presses in Spectron.com weren't always picked up though. Also, sometimes CP/M wasn't able to read the CF reliably when doin...