Spectravideo MKI, Сервисное – Техническое руководство, Страница: 125 / 134

P IN
NO . PIN NAME SYMBOL FUNCT I ON
7 - 1 4
DATA ACCESS LINES
E ight b i t inverted B i d i rect iona l bus
used for t rans fer of data , contro 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 enabled
by RE .
24
CLOCK
CLK Th is input re qui res a f ree-running
squa re wave c lock for internal t iming
re fe re nce ,
2 MH z
for
8"
drives , 1
MHz
for mini-drive s .
38
DATA REQUEST DRQ
Th is open d rain output indicates that
the D� contains assemb l e d data in Read
ope ra t ions , or the DR is empty in
Wr i t e ope rat ions . Th is signal is
reset when se rv iced by the computer
through rea ding or loading the DR in
Read or Wr i te ope rat ions , respec­
t ive l y . Use 10K pul l-up re s is tor to
+5 .
39
INTERRUPT
REQUEST
FLOPPY
DISK INTERFACE :
1 5 STEP
1 6 DIRECTION
1 7 EARLY
18 LATE
INTRQ
STEP
DIRC
EARLY
LATE
4 . 92
Th is open drain 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 ister is
wr i t t en to . Use 10K pu l l-up res istor
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 while Ear ly is act ive ( high)
shou ld
be
shi f ted ear ly for wr ite
preco•pensa t ion .
Indicates that the wr ite data pu lse
occuring while Late is act ive (high)
should
be
sh if ted late for wr ite
precompensation .