copy of SCSI 1 spec? (XT39.2)

Hiya, has anyone got a early copy of the SCSI spec which just covers SCSI 1 (i.e. 8bit bus, 5Mb/s transfers only)? I want to see if I can get the parallel port on a modern PC hooked up to one of the old SCSI/ST506 bridge boards that I have, but given that I only have 12 data out lines to play with and 5 data in (13 in if I assume a bidirectional port) things are pretty tight and I obviously need to do some loading of stuff into external registers. I've got some reasonable info on the SCSI protocol, but having a better idea of which signals do what (and at what time) would be useful. All the docs out on the web seem to be for the latest SCSI revision though (and therefore contain a lot of info that I don't need). Furthermore I only really need the low-level protocol now; software-driven higher level command structure can wait for a few days! cheers Jules