CDP1851,
CDP1851C
March 1997
CMOS Programmable I/O Interface
Features
Description
• 20 Programmable I/O Lines
THE CDP1851 and CDP1851C are CMOS programmable two-
port I/Os designed for use as general-purpose I/O devices.
They are directly compatible with CDP1800-series micropro-
cessors functioning at maximum clock frequency. Each port
can be programmed in either byte-I/O or bit-programmable
modes for interfacing with peripheral devices such as printers
and keyboards.
• Programmable for Operation in Four Modes:
- Input
- Output
- Bidirectional
- Bit-programmable
Both ports A and B can be separately programmed to be 8-bit
input or output ports with handshaking control lines, RDY and
STROBE. Only port A can be programmed to be a bidirectional
port. This configuration provides a means for communicating
with a peripheral device or microprocessor system on a single
8-bit bus for both transmitting and receiving data. Handshaking
signals are provided to maintain proper bus access control.
Port A handshaking lines are used for input control and port B
handshaking lines are used for output; therefore port B must be
in the bit-programmable mode where handshaking is not used.
• Operates in Either I/O or Memory Space
Ordering Information
PKG.
NO.
PACKAGE TEMP. RANGE
5V
10V
o
o
PDIP
Burn-In
SBDIP
Burn-In
-40 C to +85 C CDP1851CE CDP1851E E40.6
CDP1851CEX
-40 C to +85 C CDP1851CD
-
-
E40.6
D40.6
o
o
Ports A and B can be separately bit programmed so that each
individual line can be designated as an input or output line. The
handshaking lines may also be individually programmed as
input or output when port A is not in bidirectional mode.
CDP1851CDX CDP1851DX D40.6
The CDP1851 has a supply-voltage range of 4V to 10.5V, and
the CDP1851C has a range of 4V to 6.5V. Both types are sup-
plied in 40-lead dual-in-line plastic (E suffix) or hermetic
ceramic (D suffix) packages. The CDP1851C is also available
in chip form (H suffix).
Pinout
CDP1851 Programming Modes
CDP1851, CDP1851C
(PDIP, SBDIP)
TOP VIEW
(2)
PORT A
(2)
PORT B
(8)
(8)
PORT A
DATA PINS
HANDSHAKING
PINS
PORT B
DATA PINS
HANDSHAKING
PINS
CLOCK
CS
1
2
3
4
5
6
7
8
9
40 V
DD
MODE
Input
39 RD/WE
38 WR/RE
37 TPB
RA0
Accept Input
Data
READY, STROBE
Accept Input Data READY, STROBE
RA1
BUS0
BUS1
BUS2
BUS3
BUS4
36 A RDY
A
35
STROBE
34 A0
Output
Output Data
READY, STROBE
Input Handshaking
Output Data
READY, STROBE
33 A1
32 A2
31 A3
30 A4
29 A5
28 A6
27 A7
26 B7
25 B6
24 B5
23 B4
22 B3
21 B2
Bidirectional Transfer In-
(Port A Only) put/Output Data for Port A
Must be Previous- Output Handshaking
ly Set to Bit-Pro-
grammable Mode
for Port A
BUS5 10
BUS6 11
BUS7 12
CLEAR 13
A INT 14
B INT 15
B RDY 16
Bit-Program- Programmed In- Programmed Individ- Programmed Indi- Programmed Individ-
mable
dividually as In- ually as Inputs or
puts or Outputs Outputs
vidually as Inputs ually as Inputs or
or Outputs
Outputs
B
17
STROBE
B0 18
B1 19
V
20
SS
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
File Number 1056.2
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