Spectravideo SVI 318 Service – Technical Manual page 125

P IN
NO . PIN NAME
DATA ACCESS
7 - 1 4
CLOCK
24
DATA REQUEST
38
INTERRUPT
3 9
REQUEST
FLO P PY DISK INTERFACE :
1 STEP
5
1 6 DIRECTION
1 7 EARLY
18 LATE
SYMBOL
LINES
CLK
DRQ
INTRQ
STEP
DIRC
EARLY
LATE
4 . 92
FUNCT I ON
E ight b i t inverted B i d i rect iona l bus
used for t rans fer of data , cont ro l ,
and s t a t us . Th i s bus is rece ive r
enab l e d by WE or transm i t t e r ena b l e d
b y RE .
Th is input re qui res a f ree-running
squa re wave c lock for internal t iming
re f e re nce , for
2 MHz
for mini-drive s .
Th is open d ra in output indicates that
the D� cont a ins assemb l e d data in Read
ope ra t i o ns , or t he DR
Wr i t e ope rat ions .
reset when se rv iced by t he computer
through rea ding or loading the DR in
Read or Wr i te ope rat ions , respec­
t ive l y . Use 1 0K pul l-up re s is tor to
+5 .
Th is open d ra in output is set at the
comp l e t ion of any command and is
reset when the STATUS reg i s te r is
read or the command reg i s t e r is
wr i t t en to . Use 1 0K pu l l-up res i stor
to
+ 5 .
The s t ep output contains a pul se for
each s t ep .
Direct ion Output. is act ive high when
stepp ing in , act ive low when stepping
out .
Indica tes that the WRITE DATA pulse
occuring whi l e Ear ly is act ive ( high)
be
shou ld shi f ted ear ly for wr ite
preco•pensa t ion .
Indicates that the wr ite data pu lse
occuring whi l e Late is act ive ( h igh)
be
should sh if ted late for wr it e
precompens a t i on .
MHz
8"
drive s , 1
is empty in
Th is s i gnal is