Date   : Fri, 25 Jan 1991 13:24:09 GMT
From   : bbn.com!gonzalez@apple.com (Jim Gonzalez)
Subject: Need Description of Disk Parameter Block

I'm in the process of getting UNARC16 working on my Cromemco under CDOS.
Since CDOS provides only CP/M 1.3 calls, it complains when UNARC16 does a
call to the CP/M 2.x function 0x1F.  

For those who don't have their function tables handy (add another Post-It
note to your favorite email/readnews terminal :-), 0x1F is Get Disk
Parameters Block, which is used to get a pointer in order to query and
(possibly) alter aspects of the disk via this DPB.  This function is used
mostly by file compression and disk directory programs like Super
Directory.

What I need to know is the format of a DPB.  Armed with that knowledge, I
can patch UNARC16 to request the same information from with appropriate
(non-CP/M 1.3) CDOS call.  It only uses one entry from the DPB, so I'm sure
it's just looking for the block size.

By the way, Waite & Lafore's _Soul_Of_CP/M_ has been no help in this
regard.  They acknowledge the existence of function 0x1F, but say nothing
more about it or DPB's.  So much for getting to the "soul" of CP/M.  What
they *do* cover they explain pretty well, but it's annoying what they leave
out.

                               -Jim.