Bob Shannon <bshannon(a)tiac.net> wrote: Thanks for jogging my memory on this, I've been carrying the manual around for a couple of days. Looks like the 12699H, 12746H, 12747H, and 12749H boards each have a set of switches or jumpers labelled with some subset of letters A through H, and how these are set selects the base address of the board. Jumper in or switch closed is a logical 0 and jumper out or switch open is a logical 1. A is 0x004000 B is 0x008000 C is 0x010000 D is 0x020000 E is 0x040000 F is 0x080000 G is 0x100000 H is 0x200000 Some boards have some of the jumpers/switches hard wired, others require you to set them certain ways. E.g. 12746H needs A out, G out, H in and 12749H claims that A, B, C, D, G, and H are all hardwired out. All boards appear as a single chunk of memory, so a 12749H board with 256KW can only appear at 0x000000-0x03ffff, 0x040000-0x07ffff, 0x080000-0x0bffff, or 0x0c0000-0x0fffff (these are the four 256KW chunks from 0 to 1024KW). Most boards appear to be limited to appearing below 1024KW. The 12746H appears to be limited to appearing below 512KW. -Frank McConnell