Schematic diagrams and best practices

[Chuck(G)]

You don't use the DeMorgan equivalent by default. You switch to the DeMorgan equivalent to help the person reading the schematic understand what the circuit is doing.

Exactly. It's not uncommon for circuit designs to use negative logic. Using the DeMorgan equivalents can shed light on the functioning.

 

[tech58761]

It really is hit and miss as to which boards have a silkscreen layer. I should probably make note of that, I guess?

 

[cj7hawk]

It really is hit and miss as to which boards have a silkscreen layer. I should probably make note of that, I guess?

Can you embed a reference grid over a photograph of the PCB?

Or a PCB and Chip outline diagram ( like a wireframe view of the PCB ) that just shows where the chips are and what they are.

A silkscreen is nice, but sometimes a simple diagram solves the problem much more quickly,.

This sort of information is really nice to have when you have an unfortunate even and the chip cooks and the markings are lost.

 

[tech58761]

I do need to take pictures of the boards, but I need to find a good setup that doesn't underexpose or leave visible glare on them.

But - I'm rapidly running out of steam on this project... A sudden loss of confidence in my ability to draw a good schematic (there are two boards that are impossible to rearrange and unify without going to max sheet size). Finding all but two of the boards I sought has mostly satisfied my curiosity (of the two that remain, one is a potted assembly and the other is unobtainium - all I have for the latter is a picture). There were a few forum threads I made elsewhere seeking some information, and nobody has been interested enough to provide useful input.

And this after running into a similar brick wall on my other project on another system from that same era. Discouraged? Looks like I am.

 

[cj7hawk]

I do need to take pictures of the boards, but I need to find a good setup that doesn't underexpose or leave visible glare on them.

But - I'm rapidly running out of steam on this project... A sudden loss of confidence in my ability to draw a good schematic (there are two boards that are impossible to rearrange and unify without going to max sheet size). Finding all but two of the boards I sought has mostly satisfied my curiosity (of the two that remain, one is a potted assembly and the other is unobtainium - all I have for the latter is a picture). There were a few forum threads I made elsewhere seeking some information, and nobody has been interested enough to provide useful input.

And this after running into a similar brick wall on my other project on another system from that same era. Discouraged? Looks like I am.

I thought the schematics were pretty good - definitely above average - but you did ask for what more you could/might do with them so you got lots of responses -

My apologies if my responses came across as overly critical though - I think it's an interesting project. It's only because someone like you did this with something else out there that we have information on just about everything that was lost in the 90s.

 

[tech58761]

Well... as it is, though, it did wipe a good chunk of the enthusiasm I had.
I have other things that now need my attention and I'm in the process of moving this to cold storage.
I did find one of the few original schematics a coworker misfiled years ago.

 

[cj7hawk]

I quite like that schematic also - It tells a story. There's things I'd have added to it from the perspective of a tech reading it ( eg, localised labels outside of the chip from which they originate - so I don't have to follow lines to tell which is an address line ) but it's still easy enough to understand. I like it when the lines flow like that.

In any event, your schematics were completed, are still of sufficient quality, and there's no real need to return to them - Apply what you learn to the next round.

I just recently finished writing an assembler pair. Just a couple of weeks ago. The process took me a few years. First I wrote a simple cross-assembler, then I write a native assembler, and for that I asked this forum for some suggestions, and I got flooded way more in my thread... I took some idea, others I rejected, and some I liked but I could never find a good way to make them work. Then I finished the cross-assembler as a third project to replace the original simple assembler I wrote. There's a lot I learned from the process, but I never took that back to the original assembler I wrote. I'll just leave that one the way I originally wrote it, and concentrate all my future efforts around the two new paired ones ( A matching z80 native assembler and a Windows 10/11/Linux Cross assembler ).

No one will ever use it ( except for me, most likely ) and I will continue developing it because it's a fun project. When the enthusiasm wanes, it's time to find another fun project