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10.0.0 Data Communications
10.1.0 INTRODUCTION
The communications adapter (BSCA/SDLC) is an
optional feature that gives the System/32 the
ability to function as a po\nt-to-point or multi-
point processor terminal. Data is transmitted or
received serial-by-bit and serial-by-character over
voice grade communication channels (switched or
nonswitchedL The system can be connected to a
half-duplex or full-duplex facility but the adapter
operates in half-duplex mode only; that is, trans-
mission of data is only in one direction at a time.
During transmit operations, each byte to be trans-
mitted is sent to the communications adapter
where the data is serialized and then sent one bit
at a time to the modem. The modem, in turn,
sends each bit to the receiving terminal over the
communications network.
During receive operations, the communications
adapter receives each bit from the modem and
assembles the bits into bytes (deserializes). Each
byte of data is then sent to the processing unit as a
result of a character micro interrupt.
10.1.1 Data Communications Abbreviations
The following abbreviations are used with BSCA:
AA
AAC
ACO
AEO/AEL
AEO Seq
bps
BSCA
CBS
CCITT
CCT
CD
CDT
CSCD
CTS or CS
C1
DA
DAA
db
DPSK
DR
DSR
DT
DTE
DTR
EC
EIA
FET
F-O
LL
M-P
N/C
NRZI
PC1
Preamp
PSN
PTT
Rcv
RI
Automatic answering
Automatic answering, automatic
calling
Automatic call origination
Automatic equalizer
Automatic equalization sequence
Bits per second
Binary synchronous communica-
tions adapter
Data coupler for modem with AA
International Telephone and Tele-
gragh Consultative Committee
Coupler cut through
Carrier detect
Data access arrangement for man-
ual calling and answering
Clear to send, carrier detect
Clear to send
Adjustable equalizer for use with
type 3002 LL channel with C1
conditioning
Data modem ready
Data access arrangement
Decibel
Differential phase shift keying
Data ring
Data set ready
Data tip
Data terminal equipment (busi-
ness machine)
Data terminal ready
Edge connector or engineering
change
Electronic Industries Association
Field effect transistor
Fan-out
Leased line (dedicated channel)
Multipoint (not M-P implies point-
to-point, P-P)
Normally closed
Nonreturn to zero inverted
Printed circuit power supply board
Preamplifier card
Public switch network
Post telephone and telephone
Receive
Ring indicate
RS or RTS
SDLC
SG
SH
SN
SNBU
Standby
Sw
TB
T1
T2
T3
T4
Wrap
WT
XMT
2W
4W
Request to send
Synchronous data link control
Signal ground
Switch hook
Switched network
Switched network backup (standby)
Card at D6 (single modem)
Switch or switched network
Terminal board
Test 1
Test 2
Test 3
Test 4
Local loop within modem
World Trade
Transmit
Two-wire line connection (implies
half duplex)
Four-wire line connection (implies
duplex, but actual duplex depends
on DTE and telephone company
equipment)
Data Communications
10-1
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