On 7/7/05, Joe R. <rigdonj at cfl.rr.com> wrote: In _this_ case, an EPROM would work fine - a 1.7MHz 1802 will in no way flake out if an EPROM appears at address $0000 rather than a bi-polar PROM. These designs used 82S123s because a) in 1977, 1702As were somewhat expensive, b) 82S123s use less board real estate, c) 32 bytes is enough for an 1802 ROM Monitor program, etc. What I'd thought of making, though, since it's not something that I'm going to be doing massive software development on, is a _GAL_ replacement - perhaps an 8-bit tri-state buffer and a 16V8 with the various bits (256) encoded as logic equations. Yes, an EPROM would work, but I happen to have a tub of GALs, and the daughter card wouldn't be any larger. It's the trick Commodore used with AUTOCONFIG on the Amiga - a PAL to simulate a 4-bit ROM that held the manufacturer/device codes requested of each board at power-on. I know it would be tedious, but it should work. Perhaps. I myself wouldn't need more than about 10 82S123s, and a similar number of whatever PROMs are on the OMNIBUS KM8AA (if I ever wanted to write a custom bootstrap for some as-yet-unbuilt OMNIBUS SCSI card). Other than that, I'm not a big consumer of PROMs. The last time I burned one was probably 1985. -ethan