[sdiy] Analysis of the TB-303 CPU timing

Tony K weplar at gmail.com
Thu Mar 16 20:04:48 CET 2017


I read out the SH-101 code so busy disassembling that one, but always happy to look at more Roland music software. 
(nudge nudge wink wink)

Incidentally it's been a while , which micro they using in there ? My XDASM cross-disassembler covers most of the popular ones of the day.


Tony

> On Mar 16, 2017, at 2:01 PM, Gordonjcp <gordonjcp at gjcp.net> wrote:
> 
>> On Thu, Mar 16, 2017 at 03:28:27PM -0000, Colin f wrote:
>> 
>>> While I was working on a reimplementation another guy over at the RE-303
>>> forum got this image working running on my AVR based CPU hardware using
>>> the MAME code.
>>> It runs surprisingly good, but even with a 20MHz clock it has timing
>> problems.
>>> There is a noticeable lag between clock input and reaction. About 1/2 to
>>> 3/4 of a whole clock cycle at medium tempo and the gate off latency seems
>>> to be more in the 10ms range than the 2.4ms I measured on the original
>> CPU.
>> 
>> You don't need to run it in real-time to use it to generate precise
>> measurements of the jitter & latency you would get from the real machine.
>> Did anyone disassemble the hex file to readable text ?
> 
> I could maybe take a look if someone has the hex file and a programming guide for the chip?  I'm quite deep into disassembling a car ECU right now but I bet there's hardly anything in the 303.
> 
> -- 
> Gordonjcp MM0YEQ
> 
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