General Stuff(tm)

[rubber_jonnie]

I've packed the Kaypro away until the new chips arrive. I thought I'd give it a break. It did mean that I could test the keyboard latch clip, and it works a treat.

It turns out I was given bad information about the QL's ROM socket pinout. I was told that the ROM enable line was on pin27 and A14 was moved to pin22. This was wrong. A14 was still on pin27!

Easy fix, just plug the trailing wires (with chip pins soldered on the ends) into the other position in the other socket and bingo! Minerva boots.

Nice one, but annoying the info was duff.

[stephen_usher]

Yeah. It would have meant one fewer bodge wire to wrestle with too if I'd known.

[stephen_usher]

The Z80 SIO/0 has arrived and the AY-5-8116 chips have been posted (apparently) so I can get back to the Kaypro later in the week.

Tonight I should have a load of right-angled "tactile" switches arrive from Amazon so that I can fix my bike lights/indicators.

Why do they call then "tactile" switches? They're switches which seem to have the least amount of tactile feedback of any switch known to man except maybe the ZX81 keyboard. The only tactile bit about them is the dimple they make in your finger when you press on the tiny button.

[rubber_jonnie]

The Z80 SIO/0 has arrived and the AY-5-8116 chips have been posted (apparently) so I can get back to the Kaypro later in the week.

Tonight I should have a load of right-angled "tactile" switches arrive from Amazon so that I can fix my bike lights/indicators.

Why do they call then "tactile" switches? They're switches which seem to have the least amount of tactile feedback of any switch known to man except maybe the ZX81 keyboard. The only tactile bit about them is the dimple they make in your finger when you press on the tiny button.

I'm in a similar position waiting for stuff for the C128, lord know when it'll get here, especially since the C128 ROM is coming from Germany...

Totally agree about the tac switches, they have all the tactile feel of a piece of wet warm lettuce.

[stephen_usher]

Is there a ROM image and socket pinout on-line? You may be able to fit a 27C256 etc. in there for the time being.

P.S. There are images and the pinouts look the same as a 27C256. The only fly in the ointment might be if Commodore selected to use active high of the OE and CE pins of the 23C256, which is an option given by the manufacturer, so you'd need a 74LS04 to invert them.

[rubber_jonnie]

Is there a ROM image and socket pinout on-line? You may be able to fit a 27C256 etc. in there for the time being.

P.S. There are images and the pinouts look the same as a 27C256. The only fly in the ointment might be if Commodore selected to use active high of the OE and CE pins of the 23C256, which is an option given by the manufacturer, so you'd need a 74LS04 to invert them.

TBH I spent rather more time on the Coco than I'd planned, so I didn't look at it, though I have more than enough spare 27C256's to play with.

I'll have to check it out though, I'm sure it's doable and I have no doubt I have an inverter in my stock somewhere. Trouble is it's now back into the usual weekly activities, and I don't really have any free time in the evenings at the moment due to work and Karate, so I'm a bit restricted to the weekends.

[stephen_usher]

Fair enough. I'm getting the opposite a bit at the moment, with no time at the weekends, at least for the next two or three.

Next Weekend: Saturday, deliver a bread maker, mugs and kilner jars over to Camberley. Sunday, trip over to Cromer (Norfolk) to rescue a machine.
Weekend after: Assisting with the model railway club annual exhibition, "Abrail24", Friday set-up, Sat & Sun help and teardown.

The weekend after that I may have to pop down to Cornwall.

[rubber_jonnie]

Fair enough. I'm getting the opposite a bit at the moment, with no time at the weekends, at least for the next two or three.

Next Weekend: Saturday, deliver a bread maker, mugs and kilner jars over to Camberley. Sunday, trip over to Cromer (Norfolk) to rescue a machine.
Weekend after: Assisting with the model railway club annual exhibition, "Abrail24", Friday set-up, Sat & Sun help and teardown.

The weekend after that I may have to pop down to Cornwall.

Definitely the opposite to me!!!

Cromer is nice though, I do like it, good luck with the other stuff :)

[stephen_usher]

Hmm... Just recapped the Astec power supply which used to be in my Third Coast Technologies disk unit.

Replaced the RIFAs and most of the other caps (any which looked odd on the tester) and...

The +5V is way too high, at 5.7V with a load. It looks like the only way you can adjust it is by replacing resistors. Why didn't they just add a trim? It wasn't a cheap PSU at the time and was an off the shelf product. *sigh*

Here's the regulation part of the circuit. R36, R37 and R38 are the voltage trim resistors.

R36 Brown Orange Black Brown Red (1.3K +/- 2%)
R37 Green Blue Orange Gold (56K +/- 5%)
R38 Orange Black Brown Red (1.3K +/- 2%)

Am I right in thinking that either R36 has to go up in resistance or R38 go down to bring the voltage down?

[stephen_usher]

OK. I think that it's a load issue. The hard drive isn't pulling enough load.

If I stick a car bulb on the +5 rail it comes down to a more acceptable 5.1V. Still a bit high.

So, Third Coast Technologies over speced the power supply. The drive I'm using is from the early 90s so should be pulling about the same as the original 5.25 half height Seagate 27MB drive.