Date   : Tue, 05 Sep 2006 18:08:50 +0000
From   : Jules Richardson <julesrichardsonuk@...>
Subject: Re: *INFO

Joel Rowbottom wrote:
> At 10:07 31/08/2006, Tennant wrote:
> 
>> I've long since lost my EPROM burner. Is it still possible to buy burners
>> (possibly ones to burn EPROMs for the BEEB from a PC) and blank EPROMs?
> 
> I've got two EPROM burners. The Watford mk2 is 21V only (so 27128's), 
> whereas the other (can't remember the brand) will do 12.5V and 21V. The 
> latter was a bit annoying - the cable had been crimped on upside down.
> 
> That said, I've not managed to use either to write an EPROM - maybe my 
> EPROMs are knackered (not beyond the bounds of possibility, they're 
> old). Is there a "maximum" UV exposure time for them before they totally 
> screw up?

I generally cook 'em for about 15 minutes which seems to work well. Can you 
distinguish between not managing to write anything at all, and writing 
*something*?

Not being able to even start writing might suggest a power supply fault and 
there's a problem with the 12.5V / 21V supplies.

I think out of the last 30 or so EPROMs I've dealt with, I've only had one 
that was bad. I'd think it unlikely that all of yours were faulty (unless they 
all came from the same system and that had suffered some catastrophic failure)

What do you get if you *read* data out of your blanked EPROMs? I can't 
remember if you'll get all zeros or all ones now, but it'll be one or the other.

(my big old standalone programmer's a Z80-based thing and handles all that 
kind of stuff for me, including the idiot operator putting things in backwards 
  or displaced by a couple of pins ;)

cheers

J.