Vi-1. General - Canon A-200 series Service Manual

VI-1. General
Figure 6-1 shows a typical system cofiguration of the A-200 and peripherals.
As this figure shows, the A-200 is constructed by the main P.G.8., power supply, monochrome
displa.y adapter board or color display adapter board, one or two floppy disk drive unit(s) and
keyboard.
Coloror
Monochrome
Monitor
IIF
C V
Optional
Color or
R I RAM
Monochrome
T R
256KB
Board
C A
M
1
2 3 4 5
·16·bit l6-bit B-bit B-bit
B-bit
Data Bus Data Bus Data Bus
Optional Slots
Printer K/B K/B
Interface
Interface
(CPU8048)
CPU 8086
RS-232C FDD FDD
Interface
Interface
MDD-21l
Control Citcuit
D-RAM
ROM
'" 1:>
(.O"'l~t..
FDD
256KB l6KB
eol'\~
MDD-2l1
Personal Computer Main P.C.B.
•
: . " ....".. 'l'A~A,* ]
Power Supply
AC Power
+12V
Unit
-12V
Figure 6-1
The main P.C.B. consists of the
BOB6
16-bit microprocessor, 256K bytes of system RAM, 16K­
byte ROM which contains the power-on diagnostic program, BIOS and IPL (initial program load­
er), the printer interface, asynchronous communication interface, keyboard interface, floppy disk
drive interface. Another various control circuits are also equipped with the computer in order
to work these elements effectively.
The power supply unit outputs three different power sources - +5V B.SA, + 12V2.0A and -12V
0.3A. Output voltages are stabilized with the switching regulator. therefore this unit takes less space
and is light-weight.
The monochrome display adapter board uses the
6B845
LSI as CRTC (Cathode-Ray Tube Con­
troller). The 4K bytes of static RAMs are used as video-RAM
(V-RA~)
which supports one screen
of 25 rows x
BO
characters and attribute. The 256 characters to be displayed on the screen
are involved into the BK-byte ROM. Output signals such as intensity signal, horizontal drive sig­
nal and vertical drive signal are sent from the 9-pin connector mounted on this display board.
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