v1.0: works on later 3C505 cards

Fixed Crynwr packet driver for the 3Com EtherLink Plus (3C505), for later card revisions where the stock 3C505.COM reports "apparently not present", hangs, or corrupts TCP transfers.

Download 3c505fix.zip: it contains 3C505.COM, README.TXT, COPYING and SOURCE.ZIP.

3C505 0x60 10 0x300

Same command line as the original. Loading can take up to 30 s while the card runs its self-test; -d isn't supported.

Fixes: reset wait (Crynwr's timeouts ran at double speed), acknowledging every reply from the card, even-length and interrupt-safe transmit, and per-stage startup messages. Details are in docs/TECHNICAL.md.

Tested on an IBM XT-286 (DOS 3.3) with a later-revision 3C505 at 300h/IRQ 10, using mTCP DHCP, FTP and NetDrive. Reports from other cards, especially older revisions, are welcome.

3C505.COM sha256: 4cf548819d8407ec89a523fc3fb25ec0caa9f7cb64afcbf42b49c7a971f03162