Specifications

Teletype unit to release the tape feed latch. When releasea the latch
mechanism stops tape motion only when a complete character has been
sensed, and before sensing of the next character is statthd. When the charac-
ter is available in buffer (TKB), the busy bit (BUSY) i$ cleared and the done
flag (DONE) is
set.
If the interrupt is enabled, a request is made for the bus
at level 4 (BR4). The interrupt vector is at location 60,. The DONE bit is
cleared by any instruction which reads the contents of the buffer (TKB) into
the processor. If the DONE flag is cleared before the interrupt is granted, no
interrupt will occur. The keyboard must be read within 18 milliseconds of
DONE to ensure no loss of information.
Registers1
Teletype Keyboard Status (TKS)
IS 1t 7 6 0
I
0*
l-BUSY
$&TENB
L- ROR
ENB
Bit
0 RDR ENB
Requests that one character be read from the
reader; set from the bus: (Note: Setting RDR
ENB causes tape to advance by one character
which is shifted into TK8 if DONE is cleared.)
Receipt of START bit on the serial input line sets
BUSY, clears RDR ENB and clears TKB.
6
INT ENB O-No interrupt; l-Attach the keyboard and
reader to the priority interrupt system at bus
request level 4.
7
DONE
Character available; cleared by reading the buf-
fer (TKB).
11
BUSY
Character is being read; set by RDR EN8 going
to a 1. Cleared by DONE going to a 1.
I The following notation will be used throyghout this chapter for describing registers.
0 -A power clear sets this bit to 0.
1 -A power clear sets this bit to 1.
l
-This bit can only be read from the bus.
$-This bit can only be set from the bus. If it is read, it will
always appear
as zero.
Teletype Keyboard Buffer (TKB).
I
I
&BIT CHARACTER
*
15
B 7 0
TELEPRINTER/PUNCH-On program command, a character is sent in parel-
lel from a memory location (or a general register) to the TPB shift register
for transmission to the teleprinter/punch unit. The control generates the
. .
start “space,” then shifts the eight bits serially into the Teletype u&,-and
then generates the stop “marks.” This transfer of information from the TPB
into the teleprinter/punch unit is accomplished at the normal Teletype rate
and requires
100
milliseconds for completion. The READY flag in the tele-
printer/punch indicates that the TP8 is ready to receive a new character. A
maintenance mode is.provided which connects the TPB eutput to the TKB
input so that the parallel serial and serial parallel shifting may be verified.
54