System information

To get the memory image of CP/M into the TPA configured for the desired memorv size, type
the command:
MOVCPM xx*
where xx is the memory size in decimal K bytes, for example, 32 for 32K. The response is as
follows:
CONSTRUCTING xxK CP/M VERS 2.0
READY FOR "SYSGEN" OR
"SAVE 34 CPMxx.COM"
An image of CP/M in the TPA is configured for the requested memory size. The memory image
is at location 0900H through 227FH, that is, the BOOT is at 0900H, the CCP is at 980H, the
BDOS starts at 1180H, and the BIOS is at 1F80H. Note that the memory image has the standard
MDS-800 BIOS and BOOT on it. It is now necessary to save the memory image in a file so that
you can patch the CBIOS and CBOOT into it:
SAVE 34 CPMxx.COM
The memory image created by the MOVCPM program is offset by a negative bias so that it loads
into the free area of the TPA, and thus does not interfere with the operation of CP/M in higher
memory. This memory image can be subsequently loaded under DDT and examined or changed
in preparation for a new generation of the system. DDT is loaded with the memory image by
typing:
DDT CPMxx.COM Loads DDT, then reads the CP/M image.
DDT should respond with the following:
NEXT PC
2300 0100
- (The DDT prompt)
You can then give the display and disassembly commands to examine portions of the memory
image between 900H and 227FH. Note, however, that to find any particular address within the
memory image, you must apply the negative bias to the CP/M address to find the actual address.
Track 00, sector 01, is loaded to location 900H (the user should find the cold start loader at 900H
to 97FH); track 00, sector 02, is loaded into 980H (this is the base of the CCP); and so on
through the entire CP/M system load. In a 20K system, for example, the CCP resides at the CP/M
address 3400H, but is placed into memory at 980H by the SYSGEN program. Thus, the negative
bias, denoted by n, satisfies
6.2 First-level Regeneration CP/M Operating System Manual
6-7