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PERIPHERAL COMMAND WORDS
The peripheral command words are stored in a constants area. In order to transfer the com-
mand words to a peripheral, they are moved from the constants area to memory locations 3,
4, and 5; and a select {SEL) instruction is executed.
Memory location 3 contains the address of the selected peripheral in bit positions 1, 2 and 3.
Since the commands for the peripherals are 20 bits in length and the DATANET-30 word only
contains 18 bits, two bits must be added to the two peripheral command words contained in
memory locations 4 and 5.
The two extra bits for command word 3 come from positions 13
and 14 of location 3.
Two extra bits for command word 2 come from positions 8 and 7 of
location 3:
18
14 13
8
7
3
2
1
Controller
Address
Memory Location 3 - CWl
(To controller selector only)
Memory Location 4 - CW2
Memory Location 5 - CW3
The controller selector stores the bits in positions 7, 8, 13, and 14 from command word 1
and automatically adds the extra bits onto command words 2 and 3 when they are sent to the
peripheral unit in order to have the proper length and bit configuration. This pattern is followed
for all peripherals on the controller selector.
The Disc Storage Unit (DSU)
This section contains only information special to programming the disc storage unit (DSU)
from the DATANET-30.
Additional information may be found in the manual for the DSU and
other publications.
A DSU consists of 16 storage discs.
Information can be recorded or retrieved from both sides
of each disc.
From one to four 16-disc file units can be connected into one DSU controller.
[ID£1r&~~1rc:J ~@---~--------
V-35
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