RCA 301, Programmer'S Reference Manual, Page: 141 / 235

F Block Read Record Normal (BRN)
General Description
This instruction reads from a selected cell of the Data Record File to a designated HSM location. From one
to ten blocks of information may be transferred from the Data Record File 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.
Format
Operation — F
N Selects the Data Record File Unit and number of blocks to be read as indicated below:
Number of Blocks
to be Read
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 where first character is to be placed.
B Address — B
0
must be zero (0).
B, determines if record stays on turntable after operation.
B, = odd — record returned to cage.
Bj = even — record stays on turntable and arm is placed at beginning of previously selected
band.
B
2
specifies whether EB is 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 read, stop transfer from this cell. If
900 count reached before an EB sensed, stop transfer from this cell.
B
3
addresses cells 1 through 10, with cell 1 specified by zero and cell 10 specified by 9-
Direction of Operation Standard Location
Left to right in HSM. STA (0212 - 0215)
Outline of Operation
A start signal is sent to the Data Record File and the read-write head is placed on the record on the turntable.
The contents of the cell specified in B
3
are transferred to the Record File Buffer and from the buffer to the HSM
location designated by the A Register. Transfer is accomplished one character at a time, with the contents of the
A Register being incremented by one after each character 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 from the same surface.
Final Register Contents
(A)
t
= Address of HSM location one to the right of the last character put in memory.
(B)t = (B)
t
XI-7