SN74ALS29833
8-BIT TO 9-BIT PARITY BUS TRANSCEIVER
SDAS119D – FEBRUARY 1987 – REVISED JANUARY 1995
DW OR NT PACKAGE
(TOP VIEW)
• Functionally Similar to AMD’s AM29833
• High-Speed Bus Transceiver With Parity
Generator/Checker
OEA
A1
V
CC
B1
1
24
23
22
21
20
19
18
17
16
15
14
• Parity-Error Flag With Open-Collector
2
Outputs
A2
B2
3
• Register for Storing the Parity-Error Flag
• Package Options Include Plastic
Small-Outline (DW) Packages and Standard
Plastic (NT) 300-mil DIPs
A3
B3
4
A4
B4
5
A5
B5
6
A6
B6
7
A7
B7
8
description
A8
B8
9
ERR
CLR
PARITY
OEB
10
11
The SN74ALS29833 is an 8-bit to 9-bit parity
transceiver designed for two-way communication
between data buses. When data is transmitted
from the A bus to the B bus, a parity bit is
GND 12
13 CLK
generated. When data is transmitted from the B bus to the A bus with its corresponding parity bit, the parity-error
(ERR) output indicates whether or not an error in the B data has occurred. The output-enable (OEA, OEB) inputs
can be used to disable the device so that the buses are effectively isolated.
A 9-bit parity generator/checker generates a parity-odd (PARITY) output and monitors the parity of the I/O ports
with an open-collector ERR flag. ERR is clocked into the register on the rising edge of the clock (CLK) input.
The error-flag register is cleared with a low pulse on the clear (CLR) input. When both OEA and OEB are low,
data is transferred from the A bus to the B bus and inverted parity is generated. Inverted parity is a forced error
condition that gives the designer more system diagnostic capability.
The SN74ALS29833 is characterized for operation from 0°C to 70°C.
FUNCTION TABLE
INPUTS
CLK
OUTPUT AND I/O
†
Bi
∑ of Ls
FUNCTION
Ai
∑ of Hs
‡
A
B
PARITY
OEB
OEA
CLR
ERR
Odd
L
L
H
X
X
NA
NA
A
NA
A data to B bus and generate parity
Even
H
Odd
Even
X
H
L
H
X
L
H
NA
B
X
NA
NA
NA
NA
B data to A bus and check parity
Clear error-flag register
↑
X
L
H
L
X
No↑
No↑
↑
X
X
H
NC
H
X
§
H
L
H
L
X
Z
Z
A
Z
Isolation
H
H
Odd
Even
Odd
Even
H
↑
L
H
L
A data to B bus and generate inverted
parity
X
X
NA
NA
NA
NA = not applicable, NC = no change, X = don’t care
†
‡
§
Summation of high-level inputs includes PARITY along with Bi inputs.
Output states shown assume ERR was previously high.
In this mode, ERR, when clocked, shows inverted parity of the A bus.
Copyright 1995, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
1
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