Following up on the Amstrad 386 laptop restoration
https://tech.lgbt/@nina_kali_nina/112691249304838992
We've probed the VGA card all around, and even suspected one of the chips to be dead... But as it turns out, our tinkering made the card working. "Have you tried disassembling and assembling it back" approach, with thorough washing from the corrosion, helped.
The complication with the debugging was caused by the fact that VGA D-SUB works only when turned on from DOS.
The LCD screen looks much better in person than on the photo. The shades of grey on it are quite remarkable. So far it is the second most readable monochrome screen I have, second only to Playdate.
One of the fanciest things with this laptop: a custom DIN connector with a switch that detects that there's something plugged in. If there's a keyboard connected to the plug, it switches off the internal keyboard.
The hard drive, Connor CP-3044, seemed to have issues with the inner plate. Some people on the net say that resin inside could cause issues, but that didn't seem to be the case. Instead, there were major signs of corrosion inside. The head was moving quite erratically, and the disk refused to work.
Given that the disk is not especially rare and only 42MB in size, we declared it dead. It is interesting to see the lines on the disk - it has only 980 cylinders, so only 980 head positions, and so maybe this is what we see?
I wanted to try to scavenge parts from a hard disk in a long time, so this is as good opportunity as any. There is a 8KB static RAM chip in a convenient body, a 32KB one-time programmable ROM (that can be used to figure out the internal registers of the CPU), and a Motorola 68HC11 CPU which is binary compatible with 6800 but has more registers. It is labelled as SC80566FN on the chip. IT will be fun to de-solder it and wire as a stand-alone CPU.
The biggest chip on the board is a hard drive<->IDE interface. Very specific, not very useful. Another Motorola chip on the board and a Cirrus Logic chip are unidentified.
@nina_kali_nina@tech.lgbt That's far further than I've ever gone in salvaging from failed hard drives. I've seldom gone further than taking platters as tree decorations, and head magnets (though I did swap working controllers onto otherwise-working drives with bad controllers a few times). Most of today's drives you can't even get useful head magnets out of.
I took apart a full-height CDC 525MB narrow-SCSI drive once that was still working, but no longer worth the power to spin it up. As soon as I got the end off the casing and actually saw the head array, I said to myself, "Either this drive has a seek time measured in tenths of a second," (which I knew it did not, it was quite fast actually, somewhere in the 6ms range I think) "or it has god's own head magnet."
The latter proved to be the case. That head magnet could hold a pair of welding gloves to the refrigerator door.
(Yes, if you regularly make home-made pizza, you keep a pair of welding gloves — or something equivalent — in your kitchen. Because a burn off a 500°F oven rack is no fun.)
@zakalwe D: ahaha, wonderful, thank you for sharing the story!
p.s. I have VERY sturdy gloves in my kitchen, too
@infosecdj@infosec.exchange@nina_kali_nina also a bunch of FETs in DIP4!
@nina_kali_nina the 68HC11 is so much fun!
My very first embedded dev kit was one of those with a Forth interpreter on Serial.
@nina_kali_nina if you want any assistance/inspiration/whatever with hc11 disassembly to make sense of what happens in this rom dont hesitate to tell me, I spent quite a lot of time with this cpu.
@f4grx thanks! One day, one day!
@nina_kali_nina I recently stumbled on switched DIN-connectors, too. Never knew they existed but this beauty from 1969 contains a variety of them
@stargazer it is so preeeettyyyyyyyyy (
ω)
@nina_kali_nina it was love at first sight at the second hand store. It was missing the power cord and untested and all it needed besides that was some canned air...
@stargazer does it sound lush? I bet it does
@nina_kali_nina not as lush as the tube based models one generation before, but with a built in spring reverb...
For greater lushness one of these switched DIN outputs is for a rotational speaker (Leslie style) - which is very elusive, I have not been able to find a picture of one yet