exxos's Atari, Amiga & retro forum

Those legacy TV circuitry with some specialty RF components are awfuls...

Nonetheless, here is the last subsheet for the video.


Half of the next sheet is about analog circuitry again... progress will be slow, but I am near the end !

Today schematics is the pair of extended game ports... and I could not fit it inside a single sheet.

Now starting the dma sound path... today will be the DACs


edit: I was motivated enough to finish the pre-amp and filtering (before the lmc1992)


At first, I wanted to fit all those circuit into one subsheet... not a good idea... :lol:

And the end of the audio path... Did you know that "microwire" was just a reference to the microwire protocol and not the nickname of the LMC1992 ?


The end is near... one last sheet to capture. Then I will release a beta version before the final release...

The last sheet. After all those analog circuitry, it was quite quick to capture the RAM and the jumper pads...


The github repository is up to date.

So, now I will rework a little the whole project, tweak here and there to look better. Then I will create a noob question for proofreading the beta-version, then after that, I will post a final release in the schematics subsection. (of course, the release will also be hosted at github, and I might ask to be put on the atari document archive sites, too).

This is an updated version of the PAL/NTSC encoding circuit, with

• customs symbols for the variable coils and delay line. I studied this part of the schematics on the Falcon and Mega STE for those components
• updated comments

edit : fixed the pdf, too hasty, I forgotten to validate some comment edits... now the file is good.

edit 2 : starting to mess with Kicad footprints... By luck, the Atari Document Archive has a gerber of a "Falcon" motherboard (in fact there is a text stating that it is a "Sparrow", the prototype of the Falcon), where I could take the measurements for those footprints.


Next step is learning FreeCad and and a 3d model of each one...

One delay line...

The first release candidate of the schematics is ready, I need proofreader to spot typos :
By the way, the github release candidate is here : https://github.com/sporniket/retro-comp ... v1.0.0.rc1

I also did the 3d model for the variable coils :

Busy addressing the errors and warning of Kicad's ERC for the release candidate #2... and I found a rabbit hole to explore from time to time too...


This is done by extracting the silkscreen and the component side soldermask, from the field service manual of the STe (print to pdf each page of interest), put to scale (Gimp) and converted into footprints (Kicad's "Bitmap2component" tool) targeted at the Eco 1 and 2 layers.

I have already done the cut at the bottom right. The render parameter : not realist to show the 2 Eco layers, and wait one long minute.

This is out of the scope I have set for myself (the scope being the schematics), but some groundwork will never hurt.

Looks cool to see a render of the STE board. :thumbup: