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1.2.1
CPU
16-bit processor 8088 executes the microprogram which has been
loaded previously from floppy disks into the system memory
and the ROM (
Setting of system media
Power ON
Start of ROM (
Operation of OS (CP/M-
System memory map under the OS
00000H
Basic
256KB
System
^
memory
/ / / S ' / / //
y/memo ry
(512KB)
80000H''
VRAM (32KB)
' / / / / / / / / / / / / / ;
90000H
i f l i f l i z
y / Z / / . Y / V / Y / / ,
FE000H
ROM (
FFFFFH
8
KB) to control the entire functions.
8
KB)
. Initialization of hardware other than FDD
•
controller
. Initial checks (1) RAM check
. Clearing of VRAM in display controller
. Initialization of hardware for FDD
controller
. OS loading from the system media into RAM by
I
DMA controller
86
. Henceforth management under OS.
Z ' / /
y
s
V 7 A
8
KB)
Fig. 1.2.2
System Memory Configuration
(2) ROM check
(3) Timer check
(A) Key check
'
, MS-DOS)
00000H
BIOS
OS
SUB
SYSTEM
User
area
Option
1-6
RAM ,
Firmware to link
OS to hardwares
32 KB
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