The RX11 isn't DMA... when you give a command, it reads to a silo which the driver has to dump, a character at a time, or writes the silo which has been written, a character at a time... I just checked the RT-11 RX01 driver source to confirm it... Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | email: gentry at zk3.dec.com (work) | | Unix Support Engineering Group | mbg at world.std.com (home) | | Hewlett Packard | (s/ at /@/) | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 (DEC '77-'98) | required." - mbg KB1FCA | +--------------------------------+-------------------------------------+