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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