Date   : Thu, 04 May 1989 02:32:31 GMT
From   : xanth!rlb@ames.arc.nasa.gov (Robert Lee Bailey)
Subject: Synchronization Error

In article <2382@csd4.milw.wisc.edu> paravia@csd4.milw.wisc.edu (Mark David
Kakatsch) writes:
>Hello. I've had a CPM 2.2 boot disk for a while, but just recently managed to
>get a hold of the MOVCPM program for it. When I ran it to make a 56K version
>(using "CPM 56 *"), I got a sync error. This means that the serial numbers in
>the MOVCPM program and in the CPM on the disk don't match. The only way out of
>this is to change the serial numbers to match. Is there any way of doing this
>without having to go through the problem of disassembly, changing code,
>reassembling, etc...? I have a disk editor, but I don't know where the serial
>number is stored on a CPM 2.2. disk. Also, is there any way I can use
something
>like DDT to change the number in the MOVCPM program?
>

Its been a while, but, as best I recall, the serial number is located in
the first 6 bytes at the start of BDOS.  To patch it you will need to
know the starting address of BDOS.  There are several programs that will
find the address for you: PROBE, SYSTEM, SURVEY, or STATUS.  When you
find the BDOS entry, it should start on a boundry like xx00H.  The
actual BDOS entry point is xx06H.  I believe that the bytes between
xx00H & xx06H contain the serial number of your CP/M.  I am not sure
where the serial number is located in MOVCPM.  Maybe some other kind
soul can tell you where it is in MOVCPM.

Hope this helps. 

               Bob Bailey