[sdiy] Understanding 80s Synth Architectures

[grant musictechnologiesgroup.com]

I agree it must have been a focused effort to pull that off. As a casual 
observer I can say that it was most definitely written in assembler (as 
almost everything was at that time). Your closest HLL would probably 
have been PL/M at the time (but that was Intel focused).

GB


------ Original Message ------
From: "rburnett at richieburnett.co.uk" <rburnett at richieburnett.co.uk>
To: "Synth-Diy mailing list" <synth-diy at synth-diy.org>
Sent: 2/5/2022 10:16:02 AM
Subject: Re: [sdiy] Understanding 80s Synth Architectures

>Wow, that is pretty impressive.  And a substantial undertaking to figure
>out how it all works and then comment it!  How long did that take you!?
>
>Do you think the original code was written in assembly, or compiled from
>a higher level language like C?
>
>-Richie,
>
>On 2022-02-05 04:10, Anthony via Synth-diy wrote:
>>  In case you're interested in understanding how the firmware of these
>>  80s synthesisers was implemented, I've done an annotated disassembly
>>  of the Yamaha DX7's firmware ROM. This repository contains a lot of
>>  information regarding how the synth itself functioned, and was
>>  designed. Hopefully it provides a little bit of insight into how
>>  synths in this era were designed! That's the reason I began this
>>  project. I was interested in understanding the exact same topic.
>>
>>https://github.com/ajxs/yamaha_dx7_rom_disassembly
>>
>>   ------- Original Message -------
>>  On Friday, February 4th, 2022 at 9:22 PM, ackolonges fds via Synth-diy
>>  <synth-diy at synth-diy.org> wrote:
>>
>>>  Hi Everyone,
>>>
>>>  As the local SDIYer I sometimes get asked to try and fix synths
>>>  from the 80s like various Rolands, Korgs, Oberheims etc. and I
>>>  generally just try to pinpoint the rough area of the issue and
>>>  replace logic chips until the issue is resolved...
>>>
>>>  Most of these synths have a CPU connected to everything via a
>>>  parallel address bus and a parallel data bus, with all sorts of glue
>>>  logic chips doing various things. They also usually just have 1 DAC,
>>>  time-domain multiplexed to all of the different parameters via more
>>>  logic chips.
>>>
>>>  Obviously this is very different to the modern ways that
>>>  microcontrollers and DACs are used in synths, and since I wasn't
>>>  around in the 80s, these older architectures are very foreign to me.
>>>  To aid in my troubleshooting efforts, I would love to better
>>>  understand the details of how these architectures work, so I was
>>>  wondering if anyone on here would be able to point me to any
>>>  resources that could explain these types of systems to me, be they
>>>  websites, articles, or books?
>>>
>>>  Thanks a lot for any advice you might have.
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