CPIM-86 Bootstrap and Adaptation Procedures
(0040:0) CS DS ES
SS
OOOOH:
(0040:) 2500H:
(0040:)
2AOOH:
Figure 8-2 CPM.SYS File Organization
G D#
1\
0 V I I I I I I I I I I I I
(CCP
and
BDOS)
JMP
INIT
JMP
SETIOB
(BIOS)
INIT:
..
JMP
OOOOH
GD#1
is
the
Group
Descriptor containing the A-Base value followed
by
a "0"
terminator. The BIOS contains
an
"INCLUDE"
statement
that
reads the
appropri-
ate file containing the disk definition tables.
The CPM.SYS file is read by the
LOADER
program
beginning
at
the address given
by A-Base (byte address 0400H),
and
control
is
passed
to
the
INIT
entry
point
at
offset address 2500H. Any additional initialization,
n,ot
performed
by
LOADER,
takes place in the
INIT
subroutine. On completion,
INIT
executes a
JMP
OOOOH
to
begin execution
of
the CCP. The actual
load
address
of
CPM.SYS
is
determined
entirely by the address given in the A-Base field which
can
be changed if you wish
to
execute
CP/M-86
in
another
region
of
memory. Note
that
the region occupied by
the operating system must be excluded from the BIOS memory region table.
8-5
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