Vintage Synth Repair

On Monday 21 April 2008 10:47, oxygeno1313 wrote:
> You can't just replace the CPU 8049 with another 8049, you need get
> it from roland if still available or from other 101 working CPU.
>
> The fact is that the CPU it's programmed, it has an internal ROM.
> the same processor as Polysix, Juno 60 and other synthesizers.

I was wondering how long it was going to take before somebody brought this 
up. :-)

> The other option is to take a working CPU and copy the information
> with a burner capable to read and write 8049 and buy a new 8049 or
> 8749.

Nope.

> The difference between 8049 and 8749 is that the first one you 
> can program it just one time and you can't erase the information.

That's incorrect.  Those are not "One-time Programmable (aka OTP) devices,  
they're mask-programmed,  which means that this gets done at the factory 
where the chip is made.  Which means that they're only practical for high 
volume applications.

> The 8749 it's the same version as 8049 but it has a EPROM, that you
> can erase it with a UV Eraser.

Yup,  but I'm not sure that you can take one and just drop it into a socket 
that's intended for an 8049 and have everything else work with no changes. A 
detailed examination of the datasheets might answer that one...


-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin