Hi Mike,

I think it is common. I think a lot of these parts were ordered pre-programmed
at the factory, so a lot of "New" old-stock parts may actually be programmed,
and it would be difficult for a distributor to tell without actually testing.

For what it's worth, I hadn't heard of Unicorn at that time, and by now, I have
bought a number of parts from them, and have found their service and their parts
to be excellent. I would definitely call them if your part it pre-programmed.

A while back, I repaired an Asteroids Deluxe board, and I bought several 74S287
and 82S129 proms from one mail order company and Fry's, and found them all to be
pre-programmed. At first I thought I was doing something wrong. Here's the
thread:

http://groups.google.com/group/rec.games.video.arcade.collecting/browse_thread/t\
hread/f9b9c721a8130baa/8281bfdf48f56808?q=#8281bfdf48f56808

I finally got a couple of blank PROMS from a vintage arcade parts seller online.

BTW, here's my repair log for that board:

http://groups.google.com/group/rec.games.video.arcade.collecting/browse_thread/t\
hread/9e7c79a72ed8a8af/673211fb622143f1


Dave