Bell System 921A Description And Operation

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BELL SYSTEM PRACTICES
AT & TCo Standard
CONTENTS
1. GENERAL
2.
PHYSICAL DESCRIPTION
3. FUNCTIONAL DESCRIPTION
HUMAN INTERFACE
DAT A INTERFACE ACCESS
MEASUREMENT HARDWARE
MICROCOMPUTER
SECTION 107-402-100 .
Issue 3, October
1979
921A DATA TEST SET
DESCRIPTION AND OPERATION
PAGE
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13
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CONTENTS
PAGE
Inquiry Response, Switched Carrier
Test (IR SW) . . . . •
67.
Inquiry Response, Continuous Cafrier
Test (IR CONT) 69
K. Distortion Tests
L. Data Services Tests
M. Self-Tests
5. APPLICATIONS OF TESTS
4. DESCRIPTION OF DTS OPERATION AND
TESTS 26
26
31
A. Loopback Line Tests
71
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74
75
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DTS OPERATION
DESCRIPTION OF TESTS
A.
Utility Displays
B.
Utility Routines
C. General Purpose
D. Line Operations
E.
Interface Operations
F .
Programmable Clock
B. Start-Up Monitoring Test
C. Loopback Start-Up Test
D. Isochronous Distortion
Monitoring Test
32 77
32
33
36
37
39
E. Full Duplex Start-Stop Distortion Test
F. Preprogrammed Terminal Test
6. REFERENCES
1. GENERAL
77
77
79
G. Assignable Connections 41 1.01
This section provides a description and
operation of the 921A data test set (DTS),
hereafter ref erred to in this section as the DTS.
H. Sequence Generator and Error Tests . 41
I. DDS Codes
J.
Start-Up Tests
One-Way Test
61
64
65
1.02
A third version of the DTS (Version 3) has
been developed to provide increased tesdng
capabilities for new data sets and services and to
improve on the capabilities of Versions 1 and· 2,
This section has been reissued to incorporate these
NOTICE
Not for use or disclosure outside the
Bell System except under written agreement
Printed in U.S.A.
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