System Block Diagram - Radio Shack TRS-80 Service Manual

1.3 SYSTEM BLOCK DIAGRAM
The System Block Diagram (Figure 1.2) shows the various internal components and connections of the Model 4P
Microcomputer.
# 1
FLOPPY
DISK
DRIVE
8790121
CONNECT TO
RS-232-c
SERIAL
PORT
FOC CABLE
#8709457
# 0
8790121
FLOPPY
DISK
DRIVE
#8709456
DC FAN
*8790406
#8709460
DC HARNESS
RS-232-C
SERIAL
PORT
I/O
BUS
PORT
KEYBOARD CABLE
RESET SWITCH
CABLE
#8709457
E1
# 8 7 D
70-KEY KEYBOARD
iB790530
[J
~~8~~OT
ROM
64K OR 128K RAM
REAL TIME . ._ _..
CLOCK VIDEO
INTERFACE
HI - RES KEYBOARD INT.
GRAPHICS LINE PRINTER INT.
BOARD
r/o
PORT INT.
(OPTIONAL) RS232-c SERIAL
INT. FLOPPY
DRIVE INT.
HI-RES GRAPHICS
BOARD INT.
#8709427
LINE
PRINTER
PORT
RESET
SWITCH
8489071
#8709455
CRT PC
BOARD
iB790612
CONTRAST
CONTROL
#8261150
POWER
SUPPLY
#8790049
POWER CORD
#8709475
50---4'
VIDEO HARNESS
#8709452
BRIGHTNESS
CONTROL
#8262450
Figure 1-2. Model 4P Block Diagram
5