Tandy 1000 SL Technical Reference Manual page 263

5 . 4 AUTOREPEAT
The - - o n
default condition W i l l cause the last key pressed to
repeat at 1 0 . 9 characters-per-second after a 500 millisecond
delay. This may be changed b y the
system when
the keyboard is
using the AT Canrmnications Wde.
5 . 5
-
The
keyboard is capable of storing 1 6 scan codes in a first in/
first out (FIFO) circular buffer. When the buffer overfluws, the
last code is replaced b y a Hex 00, in AT W e and a Hex FF, in XT
Mode,
5 . 6
!?X' A TUS
INDICATORS
T h r e e
L E D Status Indicators are provided: Num Lock, Caps Lock,
and Scroll Lock,
T h e s e
indicators are located in the keytop of each respective
key.
The
keyboard will power up with a l l indicators OFF, except
when the host system (such as the
Tan@
3000 NL) sets them t o
a .
The
interface consists of two bi-directional lines, clock and
data, which are controlled b y 74Ls125 equivalent buffers. The
keyboard side is terminated by 2200
Ohm
resistors. All voltage
levels are
?TL
catpatible and the keyboard drivers are capable of
sinking 2 0 m~ minimum including the current
sourced
b y the pullup
resistors on the keyboard,
The
connector is a 5-pin
DIN
connector. Connections are shown in
the follming table.
Table 4
PIN
#
SIGNAL
1
CLocu
2
DATA
3 No
C0NNM;rrION
4
IQGIC GFaJND
5 +5 VOLTS
Dc
24