RCA 301 Programmer's Reference Manual page 143

G Block Read Record Simultaneous (BRS)
General Description
This instruction reads from the Data Record File controlled by the Record File Control Unit to a designated
HSM location. From one to ten blocks of information may be transferred from the Data Record Fde with one
instruction. A cell may contain a block of one to 900 characters of information to be transferred. In reading, the
end of the block of information is designated by an EB symbol, or a count of 900 characters in the cell. This instruction
is performed in the Simultaneous Mode.
Format
Operation — G
N Selects the Data Record File Unit and number of blocks to be read as indicated below:
Number of Blocks
to be Read
First File
Second File
A Address — HSM location where first character is to be placed.
B Address — B must be zero (0).
0
B, determines if record stays on turntable after operation.
B, = odd — record returned to cage.
B, = even — record stays on turntable and arm is placed at beginning of previously selected
B specifies whether EB sensed or not.
2
B — 1 — block is terminated on counting of 900 characters.
2
B = 0 — count or EB recognition.
2
900 count reached before an EB sensed, stop transfer from this cell.
B addresses cells 1 through 10, with cell 1 specified by zero and cell 10 specified by 9.
3
Direction of Operation
Left to right.
Outline of Operation
Initially this instruction is staticized in the Normal Mode. If the Simultaneous Mode is free and the SMDI
button is not on, the contents of the NOR, N, A and B Registers are transferred to the SOR, M, S, T Registers
respectively, and this instruction is executed in the Simultaneous Mode. A start signal is sent to the Record File.
The contents of the cell specified in T
interruptable, from the buffer to the HSM location designated by the S Register. Transfer is accomplished one
character at a time, with the contents of the S Register being incremented by one after each character transferred.
When the end of a block is reached, determined by T
operation is terminated. The record does not have to be returned to the cage to perform additional read or write
instructions on the same surface.
Final Register Contents
(S)f — A ddress of HSM location one to the right of the last character put in memory.
(T) - (B)i
f
1 2
2
1
B
A
band.
If EB sensed before 900 characters have been read, stop transfer from this cell. If
are transferred to the Record File Buffer and when the Normal Mode is
3
6
4 5
3
6
4 5
3
F
D E
C
, M is decreased by 1. When M is decreased to zero, the
2
10
7 8 9
0
8 9
7
I &
G H
XI-9