Re: [M100] TRS-80 Model 100 schematic transcribed to KiCAD

[Brian Brindle]

Fantastic work! Thank you for sharing!

Brian


On Fri, Jul 29, 2022 at 10:12 PM Henner Zeller  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.
>

Re: [M100] TRS-80 Model 100 schematic transcribed to KiCAD

[Henner Zeller]

>
>
> Ohh, that is a very nice scan indeed, nicely readable! I didn't find it
> coming up in a search,  my sources were the ones I listed in the README.
> The URL you supplied looks a bit ephemeral - is there a stable URL
> somewhere (Maybe upload it to archive.org) ? I'd also like to link it in
> the README if you don't mind.
>

Ah, found it:
https://archive.org/details/trs-80-model-100-main-pcb-schematic-from-tech-ref-manual/
Added the link to the README.

-h

> TRS-80 Model 100 Main PCB Schematic (from Tech Ref Manual).jpg
>> 
>> --
>> *From:* M100  on behalf of Henner
>> Zeller 
>> *Sent:* Saturday, July 30, 2022 2:11 AM
>> *To:* m100@lists.bitchin100.com 
>> *Subject:* [M100] TRS-80 Model 100 schematic transcribed to KiCAD
>>
>> 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.
>>
>

Re: [M100] TRS-80 Model 100 schematic transcribed to KiCAD

[Brian White]

This is wonderful, thank you!

bkw

On Fri, Jul 29, 2022, 10:12 PM Henner Zeller  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.
>

Re: [M100] TRS-80 Model 100 schematic transcribed to KiCAD

[Scott McDonnell]

Maybe a good thing you never found it! You might not have done the Kicad 
schematic.Great work and thanks so much for sharing it!
 Original message From: Henner Zeller  Date: 
7/30/22  12:51 AM  (GMT-05:00) To: m...@bitchin100.com Subject: Re: [M100] 
TRS-80 Model 100 schematic transcribed to KiCAD On Fri, 29 Jul 2022 at 21:23, 
you got me  wrote:






The job you did must have taken a loong time. Yes, about 
two weeks working on it in the evenings. I started with the power-supply 
section, but then I just kept going. Time-consuming was to create a bunch of 
new symbols to match the ones in the original schematic in pin-out to keep the 
same visual flow.I am happy about the result.Perhaps some people will be able 
to make a M100 kit in time for the 40th anniversary. Thank you for your hard 
work!This seems to be in reach. I do consider using the scans of the PCB to 
maybe, import these as images of the copper, assign the nets and see if this is 
a good way to re-create the PCB electronically. Maybe not as easy as the PCB 
image in the manual has the silk-screen on top of it - so some re-work 
required. For an actual re-build ... there are some parts that don't exist 
anymore (is the 80C85 still in production ?), and some that can be simplified 
(say the 4x8k modules which each are 4x2k with their four enable lines could be 
replaced with a single 32k static ram), and others could probably left 
unpopulated entirely (who needs a modem with a pulse dialler ?). Many parts of 
the era that don't exist anymore can be replaced with modern equivalents (40Hxx 
-> 74HCxx).




You were saying that the schematics you had access to were hard to read? Years 
ago I made a scan of the schematic in what I considered to be 'high 
definition'. Ohh, that is a very nice scan indeed, nicely readable! I didn't 
find it coming up in a search,  my sources were the ones I listed in the 
README.The URL you supplied looks a bit ephemeral - is there a stable URL 
somewhere (Maybe upload it to archive.org) ? I'd also like to link it in the 
README if you don't mind.Cheers,  Henner.TRS-80
 Model 100 Main PCB Schematic (from Tech Ref Manual).jpg




From: M100  on behalf of Henner Zeller 

Sent: Saturday, July 30, 2022 2:11 AM
To: m100@lists.bitchin100.com 
Subject: [M100] TRS-80 Model 100 schematic transcribed to KiCAD
 


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.