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INTRODUCTION
The 2645
I/O
devices (display, cartridge tape units, and
printer) can be program-controlled from a computer
through use of the generalized escape sequences.
The following are examples of the escape sequence used to
control a device and/or transfer information.
ESC
&
p 2s 3d M
Transfer all information stored on the
right cartridge tape unit to the
display.
1-
DEVICE CONTROL
.1
IV
I
ESC
&
p 2d 25W
Write the next 25 bytes sent from the
computer on the right cartridge tape
unit.
USING THE GENERALIZED ESCAPE
SEQUENCE.
The generalized escape sequence for
I/O
device control is
as shown in table 4-1. Items in angle brackets
«»
are
replaced by an appropriate numerical value. Items in
square brackets [] are optiona.l.
ESC
&
p lu C
ESC
&
pIA
Rewind the left cartridge tape unit.
Fetch the status of the left cartridge
tape unit.
The
I/O
control escape sequence is initiated by the charac-
ters ESC
&
p and terminated by an upper case character
(B,C, D, F, M, P, R, S, D, W,
or A).
Table 4-1. Device Control Escape Sequences
ESC
&
P
[ <"from" device code>s]
[<"to" device code>d]
[<control parameter>p] [<device code>u] <control code>c
[ <device code>
]A
[ < read control byte> ] r
[<byte count>]w
[ <control bit> ] b
[ <control bit>] f
[ <control bit> ] m
Source Device Assignment
Destination Device Assignment
Device Command
Status
Read
Write
Copy (Compare) Record
Copy (Compare) File
Copy (Compare) All
where:
(If no value is specified, 0 is assumed.)
device codes (s, d, u) are:
1
=
left cartridge tape unit
2
=
right cartridge tape unit
3
=
display
4
=
printer
(If no value is specified, previous device assignments are in
effect.)
control code (c) is:
Control
Default
Code (c)
Device
o
"from"
1
"from"
2
"from"
3
"from"
4
"from"
5
"to"
6
"to"
7
"to"
8
"to"
9
10
Function
Rewind
Space "p" records
Space "p" files
locate end-of-data mark
Condition tape
Record file mark
Record end-of-data mark
Test cartridge tape unit
Skip "p" records immediateJy with-
out recording end-of-data mark
Turn on write-backspace-read mode
Turn off write-backspace-read mode
control parameter (p) is:
a positive (+ n), negative (- n), or (unsigned) (n) integer,
specifying the number of records or files for (c) control
codes 1 and 2.
(If no value is specified,
+
1 is assumed.)
read control byte (r) is:
0= transmit next record
1
=
retransmit last record only
2
=
send byte count before transmitting next record
3
=
send byte count before retransmitting last record read
4
=
transmit file
6
=
transmit file with byte count before each record
(If no value is specified, 0 is assumed.)
byte count (w) is:
if no value is specified, ASCII is assumed. Data is received
until a Line Feed (IF) character or 256 characters
(maximum) are received.
if a value is specified, binary data is assumed.
control bits (b, f, m) are:
o
or no integer
=
copy record (b), file (f), or all (m) from
source device to destination device.
1
=
compare record (b), file (f), or all (m) on source and
destination devices.
4-1
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