DEC DECtape 551 Manual page 21

Bits
22
23
24
25, 26
27, 28, 29
30, 31, 32
33, 34, 35
Meaning
go - tape moves if 1, tape stops
if
0
reverse motion if 1, forward motion
if
0
time enable - if 1, permit time flag to cause an interrupt
start-stop delay encoded as follows:
00 = no delay
01 = reselection delay, tape is moving but another unit was
se
I
ec ted
([5
ms~
10= turn-around delay (225 msec)
11 = start de lay (300 msec)
command function encoded as follows:
0= no data transmission
1
=';~ead
allltape as a single record, beginning with the next
reverse block mark
2 = read the next block number
3 = read data unti
I
the data control disconnects
4 = write timing and mark track (the WRTM enable switch must be
on or th is command wi
II
not be executed)
5 = write all tape as a single record beginning with the next re-
verse block mark
6 = write the next block number
7 = write data unti I the data control discpnnects (the last block
/
is fill ed out with whatever happens" to be in the data accu-
mulator and the checksum is written automatically)
tape transport number - 0 is transport
8, 1
through
7
are transports
1 through
7
interrupt channel number
For a complete description of each of the functions above, see Chapter 5, Operation.
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