Date   : Tue, 23 Dec 2008 15:19:09 +0000
From   : pete@... (Pete Turnbull)
Subject: Music 500 to Music 5000 hardware mod

On 23/12/2008 15:10, Jules Richardson wrote:
> Mike wrote:
>> If the capacitor mod is actually used, then I think it will be to do with
>> the timing of the 1MHz bus. I believe there are subtle differences between
>> the 1MHz implementation on the BBC B and the Master 128.
> 
> I've got photos here of the topsides of both 500 and 5000 PCBs, and can't make 
> out any differences between them. If there is a capacitor hack (and I've 
> heard* that tale, too) then it must be to the underside of the PCB.

Music 5000 hardware is just a Music 500 with a small alteration to 
stretch signals on one of the select lines on the 1MHz Bus, specifically 
for the Master 128 which has slightly different bus timing.  There's no 
other difference AFAIK.  The mod is a single capacitor on the underside, 
but alas I can't remember which signal or what value.  On a more 
positive note, the difference is marginal and not always required, so 
try it without and see if it works.

What really distinguishes a 5000 from a 500 is the software upgrade (a 
ROM and some disks), and you don't need to change the hardware for that.

-- 

Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York