Tandy 1000 SL Technical Reference Manual page 253

Self
Test Passed
-
AA
H e x AT
and
XT
M o d e s
The keyboard issues this cornnand upon successful c a p l e t i o n of
t h e keyboard s e l f test.
The
s e l f test c o n s i s t s of t h e following.
X T MODE
1.
&mry
is cleared.
2.
Keyboard buffer is cleared.
3.
ROM
checksum is read and canpared.
4. RAM
is
tested.
5.
Self test c a p l e t i o n code is output.
6 .
AA
Hex is output t o i n d i c a t e successful s e l f test.
7. Fc
Hex
is output to i n d i c a t e a d e f e c t i n t h e s e l f test.
AT
MODE
1. ROM
checksum is read and carpared.
2. RAM
is tested.
3.
AA
ex
is output t o i n d i c a t e successful self test.
4. Fc H e x
is output t o i n d i c a t e a d e f e c t i n t h e s e l f test.
This s e l f test is i n i t i a t e d by t h e h o s t system reset (ctrl,
at,
Delete) or by Pwe.r-on Reset. Upon successful c a r p l e t i o n of t h e
Self Test
during Paver-
R e s e t ,
t h e keyboard is set t o
X T
mude
i f t h e keyboard detects a l o w level on t h e data l i n e for m o r e
than 10 microseconds a f t e r 5 microseconds fran t h e f a l l i n g edge
of the clock l i n e . I f t h i s condition is not met, t h e keyboard is
placed i n t h e
AT
M o d e , and
Typgnatic
Rate and Delay are set to
t h e following defaults:
Typematic Rate 10.9
cps
Delay 500 milliseconds
E H O
-
EE H e x AT
and
XT
M o d e s
The
Echo
C a m m d (EE
H e x )
is s e n t i n response t o an Echo camnand
f r a n t h e host system instead of t h e normal Acknowledge (PIJK) f o r
d i a g n o s t i c purposes.
Acknuwledge
-
FA
Hex
AT
Mode
The
keyboard
sends
an Acknowledge
(FA H e x )
i n response t o a
v a l i d carmand f r a n the host
system,
with t h e exceptions of t h e
R e s e n d
and Who
cara~nds.
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