Sporniket's log on hardware stuff

[sporniket]

After the long slumber of winter, I am slowly get energy to allocate to projects. After working on an 8-bit computer, I go back to the ST -slow and steady-, warming up with dealing with the ACSI port.

Capture d’écran du 2024-04-05 09-17-37.jpg

[tOriman]

Hi @sporniket

KEEP GOING! :) :yay:

tOri

[sporniket]

Yes I keep going :)

[sporniket]

A little session today, I was a bit unsatisfied on the parts where original traces were not turning at an angle of 45 degrees... I would end up with lots of twists and turns.

Capture d’écran du 2024-04-15 21-23-52.jpg

So I reworked some of those parts to be more faithful to the original drawing.

Capture d’écran du 2024-04-15 21-32-03.jpg

[exxos]

:thumbup: I hate those "zig-zag" traces. Makes PCB designers look lazy IMO.

[sporniket]

I am usually happy with 45 degrees turn, and it's true that the result with free angles looks neater. However with Kicad, switching to the free angles mode require to switch routing mode too, to a less automated mode, so it's cumbersome -to my taste-.

I am about to finish another computer remake (the 8-bit Thomson MO5), where the orthogonal routing is more strictly used (diagonal traces where limited to a minimum), and it was quite pleasant too.

[sporniket]

With the exception of the DMA that is only partially done, all the circuitry for ACSI port and Floppy drive port is done.

Capture d’écran du 2024-04-27 05-41-55.png

DMA is wired to the data and address bus, so I will need to rework and complete the cartridge port area...

Also, I leave GND/VCC at the end for completion, although I put some of the traces here and there, when it's easy

[sporniket]

Once again, a proof that remaking the PCB is an effective way of proofreading the conversion of the schematic : here is a close-up of the U12 pins 48 and 49 in the schematics

Capture d’écran du 2024-04-28 08-06-32.png

Pins 48 and 49 are named "D0" and "D1" respectively, and doing the conversion, I "obviously" wired to the data bus D0 and D1. I did not notice the small "8" and "9" marking from the databus.

I noticed there was a problem while trying to wire that, following the pathes on my reference material and on an actual motherboard, testing continuity, and finally realized the actual wiring, and then where I went wrong in converting the schematic. This is now fixed.

It makes me recall about a mind trick, where the word "RED" is written using a blue pen, and the word "BLUE" is written using a red pen, and then asking a question where the mind will be misdirected because of the discrepancies between the visual signals and the words meaning...

[sporniket]

With the DMA and the cartridge port done, the North-West corner looks fine.

Capture d’écran du 2024-04-30 06-31-59.png

[sporniket]

The RS-232 port and the MFP is done. I spotted a missing pull-up for MFP interrupt (R105) that is also fixed.

Capture d’écran du 2024-05-01 11-46-43.png

As usual, the git repository is up to date.