Tandy 1000 SL Technical Reference Manual page 251

5.0.2
COMWNICATION MCDE 2
(AT MCDE)
The
keyboard camunicates with the host ccmputer using a
synchronous serial protocol at approximately 96OOBPS. One s t a r t
bit, eight data bits, odd parity, and one stop bit form the
eleven bit data wxd.
T h i s
conmmication is bi-directional, with
the keyboard clocking all data transfers. When no comnunications
are in progress, the data and
clock
lines are high, indicating
an idle state.
<
KEYBOARD DATA OUTPUT-AT MODE
>
Figure 3A
START D O
DI
D
' : - -
DATA
T1 ; 104ys 220%
T2
;
20ysMIN.
T3 ; 20ysMIN.
T4 ; 35p.s ?20%
<
KEYBOARD DATA INPUT-AT MODE
>
Figure 38
T5 ; 60
ys
MIN.
T6 ; 5ysMIN.
(WAITING TIME FOR HOST DATA OUTPUT)
FIGURE
3
12