backing up PAL chips

[Jules Richardson]

Philip Pemberton wrote:
> Jules Richardson wrote:
>> what's the most sensible format for backing up PAL chips such that 
>> they can be  recreated on a different system to that which they were 
>> backed up on?
> 
> JEDEC fuse map 

bugger - I was afraid someone would say that.

For some reason that's the one format that seems to not work; I can read the 
device OK, but as soon as I try and spit jedec format data down the serial 
line to the remote machine it gives me 'illegal operation' on the programmer's 
LCD display. Other formats *seem* to work, in that I get binary data at the 
remote end that is variant in nature.

> , if possible, logic equations. Strictly speaking 
> though, a JEDEC-format fuse map file is enough to copy a PAL. Equations 
> just make it easier to move to a different chip.
> 
>> ... some of which are presumably EPROM-only formats (I don't have a 
>> manual for the programmer)
> 
> Which programmer are you using? One of the Elan multipurpose programmers?

Yeah, it's an Elan universe 1000 - previous owner never found a manual 
anywhere for it, and nor have I :-(

It's possible the jedec prob. above is just user error (or, alternately, that 
the programmer is failing to read the chip despite what it says, and when I 
dump data down the serial line it's just giving me what happens to be in the 
programmer's RAM at the time)

>> is there some sort of common format/size for PALs too when reading 
>> (akin to always being able to read a 27128 EPROM as a 16KB device 
>> regardless of who actually manufactured it)? 
> 
> Not to my knowledge. You have to get the programming algorithm right 
> otherwise you'll either blow the chip (literally) or get a garbage 
> readback.

Ahh, but I mean purely for reading, not programming. This programmer seems to 
have a pretty comprehensive number of supported chips, but as it's done by 
cartridges and the programmer's old I'm unlikely to be able to find any other 
cartridges for it.

I'm mainly interested in backing up PALs to share the data online for others, 
so it's less of a concern if my programmer can't actually program them again - 
reading them is the important bit!

>  > I'm concerned that this programmer
>> might be too old to have data on some of the PAL chips that I want to 
>> archive - but if I'm only interested in archiving them (and so can set 
>> the type to something of the right 'geometry' from a different 
>> manufacturer) that's not necessarily that big a deal.
> 
> I'd be more worried if it was too new. A lot of manufacturers remove old 
> programming algorithms from their programmer firmware to make space for 
> new ones...

Well it does a good job of 80's-era EPROMs, at least, so I suspect it's good 
for any PALs from that era too. It just won't do 3-rail EPROMs or any form of 
EPROM over 1Mbit (which can be problematic for early 90's hardware)

cheers

Jules