Spectravideo MKI, Сервисное – Техническое руководство, Страница: 130 / 134

2 .
Inpu t / Output S igna l s
( 1 )
Input signa l s t o t he P r i n t e r
*
DATA
1
DATA
2
DATA
3
DATA 4
DATA
5
DATA
6
DATA
7
DATA 8
* S TROBE
* IN IT IAL
8-b i l da t a s i gna l s .
S ignal " H I GH" repre s e n t s Log ic
' 1 ' .
T h i s st robe s i gna l i s us e d to re a d in 8 b i t s of da t a .
Da t a
i s r
e
a d i n when t he s i gna l g oe s ' LOW ' .
Th i s s i gna 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 norma l l y "HIGH " . B r ing i ng the l ine "LOW"
and re t u rn i ng i t "H IGH" s t a r t s the c l ea r ing act ion
w
h ich
s e t s t he P c i n t e r to an i n i t i a l s t a t e .
Th i s s i gna l i s us e d for the se l f-p r i n t ing t e s t wh ich
is e x e cu t e d by b r ing ing t he l i ne "LOW" .
( 2 )
O u t pu t signa l s f rom t he P r i n t e r
* BUSY Th i s s i gna l i n d i ca t e s the BUSY s t a t us of the Print e r .
Wh en "HI GH" t he P r i nt er cannot accept d a ta .
* ACK Th i s s i gna l i s used to ind i c a t e that the P r in t e r i s
awa i t ing da ta .
Not e : The BUSY and
ACK
s i g na l s a r e a lway s outpu t when the P r in t e r
accep t s da ta input .
* ERROR A p r i n t e r e r ror cond i t ion cause s th i s s i gna l to go
"LOW" . Wh e n t h i s happens a l l the cont r o l c i rc u i t s
inte rna l to the P r i n t e r ha l t . Ther are two ways t o
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 of f - and then back on two seconds
l a t e r .
Input t he INITIAL s i gnal
An ERROR occurs if the dot t iming goe s ba d .
This i s a 400 KHz c l ock s i g na l . I t can b e use d with an
int e r face if neede d .
4 . 97