P O R T C4 Read; P O R T C; Write; P O R T C5 Read - Tandy 1000 SL Technical Reference Manual

P o r t C4 Read
[
Readback a l l b i t s e x c e p t b i t 3.
I n a d d i t i o n :
]
-
b i t 7 = SAD-
-
S u c c e s s i v e A p p r o x i m a t i o n
d o n e . U s e f u l when p o l l i n g
i n s t e a d o f
DMA
f o r
s u c c e s s i v e a p p r o x i m a t i o n .
b i t 3 = D I O
- -
DMA
i n t e r r u p t h a s o c c u r r e d .
To
c l e a r t h e i n t e r r u p t i t
i s
n e c e s s a r y b r i n g D I C L
low, t h e n back h i g h .
P o r t C5 W r i t e
w s 1
wso
Where:
w s
1
0
0
1
1
P W 2
0
0
0
0
1
1
1
1
P o r t C5 Read
- -
( r e s ) ( r e s )
( r e s )
Pw2 PW1 P W O
w s o
=
Waveshape
s e l e c t
b i t s
-
-
P u l s e
-
Ramp
-
0
1
1
-
Reserved
-
0
-
T r i a n g l e
-
PW1
0
0
1
1
0
0
1
1
6.25% d u t y c y c l e
1 2 . 5 % d u t y c y c l e
18.75% d u t y c y c l e
25.0% d u t y c y c l e
31.25% d u t y c y c l e
37.5% d u t y c y c l e
43.75% d u t y c y c l e
5 0 % d u t y c y c l e
Direct r e a d of
DAC
(Succ. Approx.)
(DF1,O =
1 X b i n ) .
Direct
r e a d of
Snd C o n t r o l r e g i s t e r (DF1,O = 0 1 b i n ) .
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