Spectravideo SVI 318 Service – Technical Manual page 130

Inpu t / Ou t p u t S i gna l s
2 .
I n p u t s i g n a l s t o t he P r i n t e r
( 1 )
*
DATA
1
DATA
2
DATA 3
DATA 4
DATA 5
DATA
6
DATA
7
DATA 8
* S TROBE
* I N IT IAL
O u t pu t s i g na l s f rom t he P r i n t e r
( 2 )
* BUSY
* ACK
N o t e : The BUSY and
a c c e p t s da ta inpu t .
* E RROR
d a t a
8 -b i l s i gna l s .
S ig n a l
" H I GH " r e p r e s e n t s Log i c ' 1 ' .
e
T h i s s t r o b e s i g na l i s us e d t o re a d i n 8 b i t s of da t a .
i s r
Da t a a d i n when t he s i g n a l g oe s ' LOW ' .
Th i s s i g na l i s u s e d t o s e t the P r i n t e r to an ini t i a l
s t a t e and i s n o rma l l y " H IGH " .
a n d re t u rn i ng i t "H IGH" s t a r t s the c l ea r ing a c t i o n
s e t s t he P c i n t e r t o an i n i t i a l s t a t e .
Th i s s i g na l i s us e d f o r the se l f-p r i n t ing t e s t wh ich
is e x e c u t e d by b r i ng i n g t he l i ne "LOW" .
Th i s s i gna l i n d i ca t e s the BUSY s t a t u s of the P r i n t e r .
Wh e n "H I GH" t he P r i n t e r cannot a c c e p t d a ta .
Th i s s i gna l i s u s e d to i n d i c a t e t h a t the P r i n t e r i s
awa i t ing d a t a .
ACK
s i g na l s a r e a l wa y s outpu t when the P r in t e r
A p r i n t e r e r r o r con d i t i on c a u s e s th i s s i gna l to go
"LOW" . Wh e n t h i s h a p p e n s a l l t he cont r o l c i rc u i t s
i n t e rna l t o t h e P r i n t e r ha l t .
c o r r e c t t h i s s i t ua t i on .
Turn the P r i n t e r o f f - a n d t h e n back on two seconds
l a t e r .
Input t he I N I TIAL s i g n a l
A n ERROR o c c u r s if the d o t t i ming goe s b a d .
T h i s i s a 400 KHz c l ock s i g na l .
int e r f a c e if n e e de d .
4 . 97
B r ing i ng the l i ne "LOW"
Ther a r e two ways t o
I t can b e use d w i t h an
w
h i ch