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CPIM-86 Bootstrap and Adaptation Procedures
8-2
THE COLD START LOAD OPERATION
The LOADER program is a simple version of
CP/M-86
that contains sufficient file
processing capability to read CPM.SYS from the system diskette to memory. When
LOADER completes its operation, the CPM.SYS program receives control and
proceeds to process operator input commands.
Both the LOADER and CPM.SYS files are preceded by the standard CMD header
record. The 128-byte LOADER header record contains the following single group
descriptor.
G-Form
G-Length
A-Base
G-Min
G-Max
1
xxxxxxxxx
0400
xxxxxxx
xxxxxxx
8b
16b
16b
16b
16b
•
G-Form
=
1 denotes a code group
•
"x" fields are ignored
•
A-Base defines the paragraph address where the BOOT ROM begins filling
memory. A-Base is the word value which is offset three bytes from the
beginning of the header.
NOTE
Since only a code group is present, an 8080
Memory Model is assumed. Further, although
the A-Base defines the base paragraph address
for LOADER (byte address 04000H) the
LOADER can, in fact, be loaded and executed
at any paragraph boundary that does not over-
lap
CP/M-86
or the BOOT ROM.
The LOADER itself consists of three parts:
•
Load CPM program (LDCPM)
•
Loader Basic Disk System (LDBDOS)
•
Loader Basic I/O System (LDBIOS)
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