W8SDZ@mit-mc.arpa (05/09/83)
From: Keith Petersen <W8SDZ@mit-mc.arpa> More from GZ@MC about ITS .COM file format: From: Gail Zacharias <GZ at mit-mc.arpa> Re: ITS binary format There are two separate issues here. First is packing 8 bit bytes into PDP-10's 36 bit words. This is unavoidable, standard, and the ITS ftp server deals with it just fine. The problem is getting the unix user end to tell ITS to do it. SEE BELOW FOR HOW TO DO THIS. The second problem is the 4-byte header put in the binary CP/M files stored in the CPM; directory. This has nothing to do with ITS, and was a decision made by those involved with maintaining this directory and related programs. SEE BELOW FOR HOW TO DEAL WITH THIS. I might suggest that someone fix umodem to recognize those header bytes (they are 93H,3AH,D8H,00H) and strip them off. umodem could also use them for their intended purpose, differentiating between ascii and binary files, so the user wouldn't have to give a "b" switch (I assume that's what the -sb below does). The TOPS-20 modem program already does this. Anyhow, unix people, here are the answers: From: bridger at rand-unix To: Gail Zacharias <GZ> Re: downloading .com files Thanks for the protocol, which enabled our resident expert, jim guyton, to develop this method of downloading binary files. At Rand-unix we are using a version of the BBN ftp program. 1. to retrieve "AR14:CPM;NAMEXX COM" from mit-mc: ftp mit-mc type i quote type "l 8" get "AR14:CPM;NAMEXX COM" longnamexx.com bye 2. to strip off the 4 header bytes: dd if=longnamexx.com of=namexx.com bs=1 skip=4 3. to download to a cpm machine: umodem -sb namexx.com bridger --end--