Commodore 64 Handbook page 86

Modems -for parallel data transmission using telephone
signalling frequencies.
020
Parallel data transmission modems standardised for universal
use in the general switch telephone network.
021
200—baud modem standardised for use in the general switched
telephone network.
022
Defines the procedures and standards for 1200 baud full
duplex communications over the public switched network.
023
6 0 0 / 1200-baud modem standardised for use in the general
switched telephone network.
024
List of definitions for interchange circuits between data
terminal equipment and data circuit terminating equipment.
025
Automatic calling and/or answering equipment on the general
swiJ ched telephone network, including disabling of
echo-suppressors on manually established calls.
026
2400 bits per second modem standardised for use on 4-wire
leased telephone-type circuits.
026 (alternative)
2400/1200 bits per second modem standardised for use in the
general switched telephone network.
027
4800 bits per second modems with manual equaliser
standardised for use on leased telephone-type circuits.
027 (alternative 1)
4800 bits per second modems with automatic equaliser
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