Tape Read Forward Normal - RCA 301 Programmer's Reference Manual

4 Tape Read Forward Normal (RFN)
General Description
This instruction brings a series of consecutive characters from magnetic tape or punched paper tape into the
HSM. Transfer from tape begins with the first character following a gap and ends when the next gap is sensed or
the specified HSM area is filled. When reading gapless paper tape, transfer begins with the first character and ends
when the specified HSM area is filled or a gap is sensed.
Format
Operation —4
N — Identification character of Tape Station, Paper Tape Reader, or Interrogating Typewriter. (See
Appendix G.)
A Address — Address of HSM location which is to receive the first character read.
B Address — Address of HSM location which is to receive the last character read.
Direction of Operation
Left to right.
Direction of Tape Motion
Forward
Outline of Operation
Initially this instruction sends a start signal to the input unit specified by the contents of the N Register.
When this input unit is a Tape Station or the Paper Tape Reader, the first character following a gap, or the next
character of gapless paper tape, is then placed in the input buffer and this instruction operates in the following cycle:
When reading other than 66 KC tape, the character in the input buffer is transferred to the HSM location
specified by the A Register. The contents of the A Register are compared with the contents of the B Register.
The contents of the A Register are incremented by one. If the comparison proved equal and a gap is passed in
sequence, PRZ is set, and the instruction terminates. If the comparison proved equal and a gap is not passed,
PRP is set, and the instruction terminates. However, the tape movement continues to gap unless gapless paper
tape is being read. If the comparison proved not equal and a gap is passed in sequence, PRN is set, and the instruction
terminates. If the comparison proved not equal and a gap is not passed the cycle is repeated.
When reading 66 KC magnetic tape two characters are transferred from tape to the input buffer and then to
HSM, and the A Register is incremented by two. Otherwise, the instruction operates as stated above.
If an EF or ED alone is read from magnetic tape, the EF/ED Normal Indicator is set. The EF/ED Normal
Indicator is not set whert reading from paper tape.
Final Register Contents
(A), = One location to the right of the last character read into HSM.
(B), = (B),
PRI (TAPE)
PRP: The A and B Registers are equal before a gap has been found on tape.
PRN: A gap has been found on tape and the A and B Registers are unequal.
PRZ: At the time a gap has been found on tape the A and B Registers are equal.
Standard Location
STA (0212 - 0215)
y ST P fo"2-!fc-
Repeatable
IX-3