From: <Paul_Koning at Dell.com> FWIW, DMC and DMR are the same at the programmer level. (Except for some trivial differences.) My notes say the limit on outstanding TX or RX buffers is 7 for DMC vs. 64 for DMR. Also, BSEL3 is a read/write reg that survives master clears on DMC but gives diag completion status on DMR (which is how INIT.SYS tells them apart). And opcode 02 is HALTR on DMR and reserved on DMC. Is there other stuff? They are somewhat different at the protocol level -- DMC uses an older version of DDCMP and has some bugs in that implementation, especially in the "high speed" (1 Mb/s) version. Buggy WRT dealing with correct implementations, or buggy even talking to each other? Just curious (I have a pair of them around here somewhere). John Wilson D Bit