RCA 301, Programmer'S Reference Manual

Page: 145 / 235

H Block W rite Record Normal (BWN)
General Description
This instruction writes from a selected HSM location to designated cells of the Data Record File under control
of the Record File Control Unit. From one to ten blocks of information may be transferred to the Data Record File
with one instruction. A cell may contain a block of one to 900 characters of information. In writing, a block is
terminated by an End of Block (EB) Symbol or a cell count of 900 characters.
Format
Operation —H
N —Selects the Data Record File Unit and number of blocks to be written as indicated below:
Number of Blocks
to be Written
1
2
3
4
5
6 7
8
9
10
First File 1 2
3
4
5 6 7 8
9
0
Second File A
B C D E F G H I
&
A Address — HSM address of first character to be written to the Record File.
B Address — B
0
must be zero (0).
Bj determines if record stays on turntable after operation.
Bj = odd — record returned to cage.
Bx — ev en — record stays on turntable and arm is placed at beginning of previously selected
band.
B
2
specifies whether EB sensed or not.
B
2
= 1 — block is terminated on counting of 900 characters.
B
2
= 0 — count or EB recognition.
If EB sensed before 900 characters have been written, stop transfer into this cell. If
900 count reached before an EB sensed, stop transfer into this cell.
B
3
addresses cells 1 through 10, with cell 1 specified by zero and cell 10 specified by 9.
Direction of Operation
Left to right.
Outline of Operation
A start signal is sent to the Data Record File and the arm is placed on the previously selected record on the
turntable. The contents of the HSM location specified by the A address are transferred to the Data Record File
Buffer and from the buffer to the specified cell. The contents of the A Register are incremented by one, and the
contents of the next memory location are then transferred. When the end of a block is reached, determined by B
2
,
N is decreased by one. When N is decreased to zero the operation terminates. The record does not have to be returned
to the cage to perform additional read or write instructions to the same surface.
Final Register Contents
(A)
t
= Address of HSM location one to the right of the last character written.
(B)
f
= (B),
XI-11