Fantastic work! Thank you for sharing! Brian
On Fri, Jul 29, 2022 at 10:12 PM Henner Zeller <h.zel...@acm.org> wrote: > Hi, > > I recently got a TRS-80 Model 100 and for fixing the the main-board I > poured over various scans of the original schematic found on > archive.org; and while it is great that these exist, the original > schematic is still somewhat hard to read, so I decided to transcribe > them to a modern schematic format - KiCAD > > I put the schema and symbols file as well as a generated PDF on github > https://github.com/hzeller/trs80-100-schematic > > Status: Transcribed the full main-board (not the LCD board). All BOM > entries (number+value) match with the list found in the documentation, > all pin-assignments are accurate. Even deduced some values that are > missing in the schematic (R162, 100Ohm discharging C78 in the reset > circuit, as well as the designator for the 10n capacitor near the > primary in the power supply .. C62). Schematic passes electrical rule > check, so at least there are no obvious mistakes in there. > > I tried to keep the original layout as much as possible for easy > recognition, but did slight changes to improve readability. > For instance, I added a gap between the 'analog' and 'digital' part so > that it is possible to print out on two sheets and glue together > without losing content (or simply folding a large print-out without > damaging important stuff). Also using IEC resistor symbols for > readability and changed capacitor units where nanofarad is better > (3300pF -> 3.3nF; 0.047μF -> 47nF); they didn't seem to use 'Nano' > back in the day. Renamed some signals to be more useful, so `Ⓐ*` is > now `RDRW*`. Used color encoding for the different buses on the system > to easier see what is going on at a glance. > > If you find any mistakes (I am sure I missed something), please file > an issue in the github's issue tracker. > > Cheers, > Henner. >
