Article-I.D.: mitre-be.8603171654.AA07440
Posted: Mon Mar 17 12:49:33 1986
Date-Received: Wed, 19-Mar-86 00:55:05 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The MITRE Corp., Bedford, MA
Lines: 35
I just noticed that "Inside Atari DOS" apparently has an error in describing
the sequence of the control bytes at the end of DOS sectors. I would
appreciate confirmation by anyone who knows.
Inside Atari DOS (IAD) says that a sector consists of 128 bytes, numbered 0
through 127, and that in DOS files only 125 bytes (0 - 124) are used for data.
(This much is true.) They go on to say that byte numbers 125, 126, and 127
are numbered as follows:
125 126 127
IAD | # of bytes actually 6 hi bits=file number low 8 bits of next-
Version| used in the sector 2 lo bits=hi bits of sector number (link)
next-sector number
Documentation supplied with David Young's OMNIMONXL resident monitor/debugger
says that the numbering is
125 126 127
The | 6 hi bits=file number low 8 bits of next- number of bytes
Truth!| 2 lo bits=hi bits of sector nr (link) actually used in this
| next sector nr (link) sector.
Based on what I can see in the actual sectors I have looked at, both with
OMNIMONXL and with another independently developed debugger, David Young's
information appears to be correct and Inside Atari DOS appears to have
incorrect information.
I would appreciate confirmation of my conclusion by others who have noticed
the error in IAD. (Also if they have any other errors I would like to be
made aware of them!)
John Sangster
jhs at mitre-bedford.arpa
!ihnp4!linus!mbunix!jhs