[sdiy]RE: Re: [sdiy] TB-303 cpu question - impossible

[rdrake]

what about these guys: 

http://www.ladyada.net/make/x0xb0x/index.html

did they reverse engineer the cpu? sample the sound of a factory 303 and burn new roms? or are you talking about something completely different (i obviously don't know much about the guts of these machines, but i'm curious).

b  

>----- ------- Original Message ------- -----
>From: rw at firstpr.com.au
>To: synth-diy at dropmix.xs4all.nl
>Sent: Wed, 16 Nov 2005 09:52:12
>
>The TB-303 is a mask programmed 4 bit NEC CPU. 
>There are no such CPUs
>available, including as far as I know any such CPUs
>with external ROM.
>I don't think there could have been an external ROM
>version, because it
>would take most of the pins to access the ROM. 
>Other than a special
>device for development, I doubt if NEC ever made a
>chip with all the
>extra pins required for operation with an external
>ROM.
>
>There is no way anyone knows of reading the ROM. 
>Probably there is a
>way of doing so as part of NEC's test procedure.
>
>So no-one has the object code.  The CPUs are not
>available in any form.
> Other CPUs in devices such as TR-606s have
>different ROM data.
>
>Its my impression that a lot of talk about this
>subject is not based in
>reality, but on optimistic hopes that what happens
>in completely
>different situations might somehow apply to the
>TB-303 CPU.
>
>It is technically possible to analyse the operation
>of the CPU and to
>create a new PCB to take its place, with some chip
>like a PIC programmed
>to emulate its functions.  That would be a huge
>project.  For the actual
>demand for CPU chips, which I guess in 12,000 or so
>TB-303s in
>existence, are failing at about one a week
>somewhere in the world - it
>is probably a lot easier to either write off the
>TB-303, buy another
>TB-303 and grab its CPU, or forget about the
>sequencer and have a MIDI
>In system installed.
>
>I have installed the Devil Fish mods, with MIDI In
>for a TB-303 without
>a CPU.
>
>   - Robin
>
>    http://www.firstpr.com.au/rwi/dfish/