Organization Of Cpm.sys - NEC CP/M-86 System Reference Manual

CP/M-86 Bootstrap and Adaptation Procedures
8-4
The command LDCOPY copies LOADER.CMD to the system tracks. These steps
produce a diskette with a LOADER program which incorporates the custom
LDBIOS capable of reading the CPM.SYS file into memory. For standardization,
LOADER executes at location 4000H. LOADER is statically relocatable, however,
and its operating address is determined only by the value of A- Base in the header
record.
You must, of course, perform the same function as the BOOT ROM to get
LOADER into memory. The APC controller provides a power-on "boot" operation
that reads the first disk sector into memory. This one-sector program, in turn, reads
the LOADER from the remaining sectors and transfers to LOADER upon
completion.
ORGANIZATION OF CPM.SYS
The CPM.SYS file, read by the LOADER program, consists of the CCP, BDOS,
and BIOS in CMD file format, with a 128-byte header record similar to the
LOADER program.
G-Form G-Length A-Base G-Min G-Max
1
xxxxxxxxx 040 xxxxxxx xxxxxxx
8b 16b 16b 16b 16b
A-Base load address is paragraph 040H, or byte address 0400H, immediately
following the 8086 interrupt locations. The entire CPM.SYS file appears on disk as
shown in Figure 8-2.