Xerox WorkCentre 385, Руководство по обслуживанию

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WorkCentre 385
Circuit Description
12/98
7 - 30
Table 3: Hardware Interface Signal Descriptions
Signal PIN No. Type Description
RS4
RS3
RS2
RS1
RS0 56
57
58
59
60 I
Register select bus
These lines are used to address interface memory registers within the
modem. When CS is active, the modem decodes RS0 through RS4 to
address one of its 32 internal interface memory registers. RS4 is the
most significant bit. In a typical design, RS0-RS4 are connected to A0-
A4 address lines of the host microprocessor.
D7
D6
D5
D4
D3
D2
D1
D0 8
9
10
11
12
13
14
15
I/O Data bus
These bi-directional data bus lines provide parallel data transfer
between the modem and the host microprocessor. D7 is the most signi-
fication bit. The direction of the D0-D7 data bus is controlled by the
READ-
φ
2 and WRITE-R/W signals. When not being written into or read
from, D0-D7
assume the high impedance state.
CS 54 I Chip select
The modem is selected and decodes RS0-RS4 when CS becomes
active at which time data transfer between the modem and the host can
take place over the parallel data bus. Typically, CS is driven by address
decode logic.
READ-
φ
2 55 I
Read enable (bus mode) or phase2 (6500 bus mode)
If 8085 bus mode is selected (EN85 is connected to ground), this
signal acts as the READ input. If 6500 bus mode is selected (EN85
is pulled-up to +5V), this signal acts as the Phase 2 clock input.
WRITE-R/W 53 I Write enable (bus mode) or R/W (6500 bus mode)
If 8085 bus mode is selected (EN85 is connected to ground), this
signal acts as the WRITE input. If 6500 bus mode is selected (EN85
is pulled-up to +5V), this signal acts as the R/W strobe.
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