Specifications

by setting a DONE bit. If the interrupt is enabled and the interrupt is granted,
the processor traps to location 70, and may immediately begin executing the
service routine for the paper tape reader.
Reghters
Paper Tape Reader Status Word (PRS)
15 15 11 11
7 7 6 6 0 0
* *
it it * *
0 0 0 0 0 0 0 0 0 0
l- l-
ERROR ERROR
L BUSY L BUSY
L L
LINT EN6 LINT EN6
L L
ROR RDR
DONE DONE
ENB ENB
Bll ~
0
RDR ENB Requests read of next character; can be set from
bus only if ERROR = 0. Clears PRB, sets BUSY.
6 INT ENB O-No interrupt;
1 -attached to priority interrupt
system at BR4. (Note: Interrupt occurs when INT
ENB is a 1 and either the error flag, ERROR, or
the done flag, DONE, becomes a 1.)
7 DONE Set by character available; cleared by reading the
paper, tape reader buffer (PRB).
11 BUSY
Set by RDR ENB going to a 1; cleared by DONE
going to a 1.
J
15 ERROR Error Flag -
Set or cleared by out-of-tape sensor
*
or off line switch.
Paper Tape Reader Buffer (PRB)
I
I
E-BIT CHARACTER
it
15
8 7
0
PROGRAMMING EXAMPLE/Gape reading subroutine (not using interrupt):
READ: INCB PRS ; enable reader
TEST: BIT $100 200 PRS
; test for error or done
BEQ TEST
; branch back if not done
BML ERROR
; branch if error = 1
MOVB PRB. RO ;~ get character from buffer
RTS R
; return to caller
ERROR:
(message type out routine)
HALT
; wait for operator intervention
JMP READ
; try again when continue switch is hit.
TAPE PUNCH-This option of a Royal McBee paper tape punch that per-
forates B-hole tape at a rate of 50 characters per second. Information to be
punched on a line of tape is loaded in an B-bit punch buffer (PPB) from a
memory location or one of the general registers. The punch flag, READY,
becomes a 1 at the completion of punching action, signaling new information
may be transferred into the punch buffer and punching initiated.
56