Its not quite that simple Tony! We have used 82S129's from Jameco with a Xeltek SuperPro III and discovered many strange facts about old bipolar ROM's. Our first order arrived with 5 parts, one 74S287A and four 82S129A's. The Xeltek lists each of these parts, as well as the other (Harris and MMI?) manufactuers seperately. These were ordered as 74S287's. The 74S287A worked fine, but several of the 82S129A's died in the burner before I discovered the settings that would get them to program and verify corretly. These then also worked fine as boot ROM's in the HP1000 CPU's. Needing more ROM's, I re-ordered and learned that the 74S287 part number was discontinued, and they offered 82S129A's as compatible parts. Ok, they worked before, so why not... The new order of 5 82S129A arrived, but were from a different manufactuer. Again several died in the burner until I found the settings that would get these to program and verify in the programmer. With a few parts left, I programed and verifed several copies of an HP boot loader (for CS/80 drives) and all verifed correctly. However NONE of these roms will load good data into the HP-1000 CPU. The data loaded into memory is all 1's. So once programed, reading is not fully compatible from device to device due to access speeds, circuit loading, and maybe the phase of the moon as well. These ROM's that load all 1's still verify in a programmer. Now I do admit the Xeltek programmer is not one of the best out there, but this is clearly a real device compatibility issue. Steve has some Harris parts in hand, and we know that ROM is used by HP, so they should work fine as boot loaders (HP also used 82S129's, but not 82S129A's it seems). All thats needed is someone with a programmer who can duplicate some existing ROM's in-hand. Tony Duell wrote: