Date   : Mon, 30 Jul 1984 07:44:03 PDT (Monday)
From   : Chapman.ES@XEROX.ARPA
Subject: Problem with Creating a file

Last weekend, I needed to do a quick and dirty test of transfering data
from one computer to another over an RS232 direct hookup.

So I entered DDT and started hand assembling a short job to create a
file, read the appropriate port, and store the data in the file. Since I
wasn't sure the data would come over (hardware parameters needed to be
futzed with), I used the debugger breakpoint facilities to watch what
was happening. I found that the FCB at 5? (Hex) (I'm at work with no
documentation, so I don't remember the number off the top of my head,
but it's the default FCB) would be set up properly according to the
documentation by the appropriate BDOS Create file call, but after the
first sector of data had been stored, the "number of sectors used in
current extent" byte was garbage. Manually reseting it to 1 and
proceeding allowed me to capture the rest of my data. The byte was
properly incremented thereafter.

Any ideas what's going on? Is it an artifact of using the Debugger? (If
that were so, I might expect the byte to keep getting clobbered.) I have
used my system (an Imsai 8080, running CP/M 2.2) with many standard
programs with no problems. I don't usually bother to write my own, but I
do when I have to. I followed the documentation in the CP/M manuals for
making BDOS calls correctly, to the best of my knowledge.

Cheryl