Zenith Z-100 PC series Service Manual page 83

Chapter 3
Theory of Operation
This chapter explains the operation of the CPU/memory card in terms of
a simplified block diagram. For more information on the operation of
this card, refer to Chapter 4, "Detailed Circuit Description."
Block Diagram
A simplified block diagram of the CPU/memory card is shown in Figure
3-l. This diagram represents only the major functions of the CPU/mem­
ory card. Refer to this block diagram while reading the descriptions in
the following paragraphs.
l
BACKPLANE BOARD CONNECTOR
,
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e/)
::l
::l
::l
TO OTHER
III
III
III
DEVICES
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l-
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0
ct
w a:
e
a:
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e
z
e
0
ct
()
8088-2
(8087-2)
BUFFER
-,
GATE
PROGRAMMABLE
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BUFFER
INTERNAL TIMER
ARRAY
BUFFER
BUFFER
INTERRUPT
h
CONTROLLER
f-I
MU
9
CRYSTAL
I
PARALLEL PORT
jE-
~
I
RAM
OSCILLATORS
AND
ROM
I
DIP SWITCHES
I+-
L..--j
KEYBOARD
I
Figure 3-1: CPU/Memory Card Block Diagram
Backplane Board Connector -- The backplane board connector is used to
connect the CPU/memory card to the rest of the system. This connector
also supplies the CPU/memory card with power from the power supply.