Bob: I don't know the exact Altair model the schematics relate to, but it's not the turnkey model. The ROM socket appears on the display/control board schematic, which has the front panel switches and LEDs. The Altair Turnkey would, I believe, have a different board in it called the Turnkey Module or something like that. If you want to see the schematic, go to my Altair32 Emulator page and look on the technical links page for the ZIP file containing scans of the schematics. I do not have an Altair, and I got these schematics from another source. The only designation on the page is "Figure 3-16; Display/Control Schematic (sheet 1 of 3)". The URL is http://highgate.comm.sfu.ca/~rcini/classiccmp/Altair32.htm I've had these schematics for a while, but I never looked at them that closely. Rich -----Original Message----- From: Kapteyn, Rob [mailto:kapteynr@cboe.com] Sent: Monday, July 28, 2003 2:37 PM To: cctalk(a)classiccmp.org Subject: RE: ROM on Altair front panel board Which version Altair ? The original Altair has no ROM anywhere. I think you are looking at the "turn-key" version. It has no switches for manual intervention, so it would have to have some intelligence, in the form of a boot-loader. I have never worked with a turn-key version, so I am not sure. -Rob -----Original Message----- From: Cini, Richard [mailto:RCini@congressfinancial.com] Sent: Monday, July 28, 2003 12:15 PM To: CCTech (E-mail) Subject: ROM on Altair front panel board Hello, all: I was just looking at the schematics for the display/control board for the Altair 8800 and saw that there is a 1702 EPROM on the board. The lowest 4-bits of the EPROM's address bus are connected to a 7493 binary counter and the highest 4-bits are connected directly to the address bus. What's the purpose of the EPROM? Did the front panel have some intelligence? Rich