Sinclair ZX80 questions

Jules Richardson julesrichardsonuk at
Tue Aug 22 12:57:44 CDT 2006

Rob O'Donnell wrote:
> At 08:30 22/08/2006, Jules Richardson wrote:
>> You know, my prototype Torch Z80 disk unit has power out at the back; 
>> I can't remember whether the production ones were like that or not. It 
>> had never occurred to me that someone would want to power the machine 
>> from it!
> There's one on eBay at the moment - Item 280020173050

Heh, I know the seller - he's tried to interest me in that one a few times :-)

My prototype one is the same design, but uses the (far more attractive) 
two-tone grey paint that Torch used for most of their systems, rather than the 
  "poop brown". For some reason they changed it for the production units...

 > - with a picture
> clearly showing the rear with a DC out connector.  It appears to only be 
> +/- 5V from the labeling, which I would have thought insufficient to run 
> a Beeb. 

Ahh, no - beebs use RS423 for serial, so only need +/- 5V internally on the 
system board. They do have +12V on the aux power connector on the beeb's PSU 
itself, but that's not used internally by the system.

I'm still surprised that there were any beebs incapable of running the Torch 
board from their own PSU though. I believe there was a change to PSU spec at 
some point early in the beeb's life though, so maybe very early systems 
couldn't cope.



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