Features; Cpu Block Diagram - Radio Shack TRS-80 Service Manual

3. CPU (Central Processing Unit) HD61913
3-1. Features
o CMOS one-chip CPU
o Built-in ROM: 100864 bits
o Built-in RAM: 1896 bits
o Built-in display driver
o Memory backup function
o
Clock: 400 kHz
Internal machine cycle: 200 kHz
Minimum instruction execute time: lOpS
3-2. CPU Block Diagram
Control signals
11
ROM
Instruction
(System
)
Program)
Decoder
0 0
-"-
~
_.
- . III
-v""
<
'tl
CD -
>-
~ Ql
-<
RAM/ROM
r
aI
Address ----"..
i
0
/
Control
Internal Bus
./
(')
..
0
:;,
...
2-
·vl,
•
?
"\./
Keyboard
ALU
Control
.(
~
~ I,
Keyboard Signals
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