couple of IC questions - mixer chips, PAL's, GAL's

Tancor · Post by **Tancor** » Wed Jun 08, 2005 1:54 pm

Hi all,

I came into a good collection of IC's, some of which I think I would like to use in a 6502 or 65816 system. I have a few problems I hope someone can help me with.

One is that I have a new set of PAL's and GAL's. I know that these are probably OTP IC's, but I don't know how I can tell if they have been programmed or not, so I was hoping someone could shed some light on what I need to do to find out if they are programmed. I wasn't sure if they could be just read by my programmer and then if they are some value they are blank, or if once programmed they couldn't be read or what...?

The other problem is I have this chip that is either a mixer chip or a midi chip, I'm not sure which - I think I would like to play with it tho to create some sound, but I can't locate any information on it so I was hoping someone on this board might either know where I can get information on or have information for a Media Vision MVA508B IC. its a 52pin plcc, and I'm having a heck of a time trying to get info on it.

Any help would be most appreciated!

leeeeee · Post by **leeeeee** » Sun Jun 12, 2005 4:31 am

GALs are reprogrammable, PALs generally aren't except for PALCE or PALEE parts.

Cheers,

Lee.

Tancor · Post by **Tancor** » Sun Jun 12, 2005 4:41 am

Is there a way to tell if a PAL has been programmed already?

leeeeee · Post by **leeeeee** » Mon Jun 13, 2005 12:19 am

Without a programmer I would guess that applying power would turn on some of the output drivers if the part had been programmed. This isn't 100% reliable as some PALs have output only pins with no output tristate.

It's a lot easier to program GALs, there are a few freely available GAL programmer designs and some very cheap commercial units. PALs are a PITA to program unless you have a programmer for that part. Even the same part from different manufacturers can need different programmers.

There are very few cases where a GAL can't replace a PAL part so unless you have 1000's of them I'd not bother and use the GALs instead.

Cheers,

Lee.