Word Polarity - Control Data Corporation INFORMATION SYSTEMS TERMINAL II Hardware Maintenance Manual

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Figure 4-S. Transmitter Word Format
Word Polarity - The transmitter output is in the TTL high
state during the idle (inactive) state. The Start bit is a
logical O. The data is inverted; that is, if bit 4 output
from the processor was a logical 1, it goes out of the
transmitter as a logical O.
These TTL levels show at the connectors as follows:
TTL 0 RJl-2, RJl-14 (RS-232-C) =
Space
AJS-6 (TTL) = TTL high
TTL 1 RJl-2, RJl-14 (RS-232-C) =
Mark
AJS-6 (TTL)
=
TTL low
Word Parity - The transmitter logic does not generate
parity.
Data Rate - The transmitter can transmit at 7S, 120, and
1200 bps.
Data Transfer/Disassembly - When the transmit data has been
correctly loaded, the two output bytes shift out as shown
in figure 4-6.
Bits 0, 1, and 2 of the load low bits output are not used
(they can have any value). Bits 3 through 7 hold Transmit-
ter Data bits 11 through 07, respectively. Bits 0 through
S of the load upper bits output contain bits 06 through 01
of the Transmitter data word. Bits 6 and 7 are ignored and
the transmit logic inserts the Start bit.
82100083 B 4-9
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