User`s guide

Page 22
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CP/M 3.0 On the Commodore 128 1 Aug 85
40 column display
A> (blinking cursor)
R A01 10
Well, I remember A> had something to do with the current
default drive, so I entered the following: B: <RETURN> and
this is what was displayed...
CP/M Error On B: Disk I/O
BDOS Function = 14
I know this is an error code – Time to hit the manuals!
While I'm looking for the error code, I will look up what the R
A01 10 displayed at the bottom of the screen means (I know,
all you CP/M veterans are probably laughing by now...). Oh,
also, I noticed that at the bottom of the screen, it has changed
from R A01 10 to R B03 00 (Could this be a hint as something
to do with disk access?).
Accessing the Manuals…
According to the Commodore 128D User’s Guide, the above
display is deciphered as follows:
This is how CP/M looks on the 128 in 40 column mode. The
screen is divided in two parts with the left half showing. I need
to use the Control Key and one of the Right Arrow keys (these
are the keys at the top of the keyboard!) to view the other part
of the screen. (Hmm, if this becomes too cumbersome, I’ll be
connecting the 80 column monitor).
The User’s Guide also states that I have access to 58k of
available RAM (in CP/M terms – TPA, or Transient Program
Area).
The opening screen shows the default user and drive letter (0
is the default and is not shown, drive A is the default disk
drive). Also, according to the manual, I can connect 4 physical
disk drives (lettered A, B, C, and D), and one “logical or virtual
drive”. I’ll investigate that later. I did check out what was
meant by the “default user” and according to the Digital
Research User’s Guide (see pg. 2-4), CP/M files can be divided
into “user” groups. There are 16 users possible numbered from
0 to 15. Here’s what the User’s Guide states,
“CP/M 3 further identifies all files by assigning each one a user
number which ranges from 0 to 15. CP/M assigns the user
number to a file when the file is created. User numbers allow
you to separate your files into sixteen file groups. User
numbers are particularly useful for organizing files on a hard
disk”.
I interpret this as a means of helping to organize when there
are likely to be multiple users (such as in a business
environment of some sort) that use the same machine. I’m
gonna have to investigate the hard drive issue later.
I think I will make a checklist of things I want to do later, so I
don’t forget…I’ll put this at the end of the article for easier
reference.
O.k., back to the manuals. The next titbit mentioned in the
128D User’s Guide mentions that a RAM Expansion module is
accessed as drive ‘M’. This is set up as a RAM Disk. The manual
mentions to reference the User’s Guide for the RAM expansion
unit being used. Since I have a 1750, I checked out the manual
to see what it says. I found another checklist item. Apparently
there is a disk that is supposed to have been included with the
REU for CP/M. I will have to research this since I don’t
remember seeing one with mine (the problems of buying a
used peripheral).
I just found a book in my collection about CP/M – it is book #8
from the Commodore 128 series published by ABACUS. Here is
what I was able to find out about those numbers at the bottom
of the screen…
“You've probably noticed that there are always some numbers
in the lower right corner during loading. Even when the initial
message disappears, these numbers don't go away. The last
line of the screen is the status line, which can't be written on.
The numbers in the corner show which block is being read
from or written to. An R stands for reading from, and a w for
writing to a block. Further down is an A or B message,
indicating the disk drive that's being used. The status line can
be turned on and off with the key combination (p. 25)”.
Now for that error message. I found in the Digital Research
Programmer’s Guide more information on BDOS errors,
“Physical and extended errors are displayed on the console in
the following format:
CP/M Error on d: error message
BDOS function = nn = filename.typ