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SECTION VII
TYPES 204B-ll, 204B-12 MAGNETIC TAPE UNITS
The Type 103 consists of a tape control and a Type 204B-ll primary
tape unit.
Up to three Type 204B-12 secondary tape units may be added to
the tape control.
The primary unit contains the vacuum system and readl
write circuitry for all four units.
The Type 103 processes 1/2-inch mag-
netic tape having a record density of 556 bits per inch.
Tape moves at a
speed of 24 inches per second during reading or writing; rewind speed is
144 inches per second.
The programmer-defined interrecord gap may be
set to a "short" gap of
O.
45 inche s or a "long" gap of
O.
75 inche s.
The
above physical properties define the following Type 204B-ll and 204B-12
tape characteristics:
1.
Data transfer rate is 13,344 characters per second.
2.
Time required to cross the interrecord gap is 19 milliseconds for the short
gap and 31 milliseconds for the long gap.
3.
Erase time is 146 milliseconds (an erase command automatically erases
3 112 inches of tape).
4.
Time to reach the first tape record is 344 milliseconds (a rewound or newly
mounted tape must be moved 8 1/4 inches before the first record is reached).
The tape control regulates data transfer between tape units and the central processor
and checks for read and write errors.
One six-bit character (occupying one tape frame) is
transferred at a time.
Data transfer terminates when a record mark is sensed in memory
or, alternately (for a read operation), when an entire tape record has been read.
TAPE STATION
o
2
3
TAPE ADDRESS
EHJOEJ
(J
MAY BE ANY NUMBER
ZERO THROUGH THREE
Figure 7-1.
Manual Controls for Type 103 Tape Control
7-1
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