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8272
A.C. CHARACTERISTICS
tA=
O'C
to
70'C,
Vcc=
+5.0V±
5%
SYMBOL PARAMETER
MIN MAX UNIT TEST CONDITIONS
ICY
Clock Period
125 ns
tCH
Clock High Period
40
ns
tRST
Reset Width
14
ICY
Read Cycle
tAR
Select Setup to AD! 0
ns
tRA
Select Hold from RD! 0
ns
tRR
AD
Pulse Width
250
ns
tRO
Data Delay from RD! 200
ns
C
L
=
100
pF
tOF
Output Float Delay 20 100
ns
C
L
= 100 pF
Write Cycle
tAW
Select Setup to WR! 0
ns
tWA
Select Hold from
WJ!!!
0
ns
tww
iiiiFi
Pulse Width
250
ns
tow
Data Setup
to
WR!
150
ns
two
Data Hold from
WJ!!!
5
ns
Interrupt.
tRI
INT Delay from RD!
500
ns
tWI
INT Delay from WR!
500
ns
DMA
tRQCY
ORO
Cycle Period
13
~s
tAKRQ
i5ACK!
to
ORO! 200
ns
tRQR
ORO!
to
RD!
800
ns
8 MHz
clock
tRQW
ORO!
toWR!
250
ns 8 MHz clock
tRQRW
ORO!
to
RD! or WR!
12
~s
8 MHz clock
FDD
Interlace
TYp1
t
WCY
WCK Cycle Time
20r4
---
--
- -
MFM=O---
~s
Note 2
r-
1..£r2_
-80--
35'0
- -
_MFM':..!..
___
tWCH
WCK
HlghTlme
250
ns
tcp
Pre-Shift Delay from WCK!
20
100 ns
tco
WDA Delay from WCK!
20
100
ns
twoo
Write Data Width
tWCH-50
ns
tWE
WE!
to
WCK! or WE!
to
WCK! Delay 20
IUU
ns
1---
----
------
tWWCY
Window Cycle Time 2
~s
MFM=O
I-.....!-
----
--
--
~B!1=..1
___
t
WRO
Window Setup to ROD!
15
ns
tROW
Window Hold from ROD!
15
ns
tROD
ROD
Active Time (HIGH)
40
ns
FDD
SeEKI
DIRECTIONI
STEP
tus
US
O
,1
Setup
to
RW/SEEK!
12
~s
Isu
~,1
Hold from RW/SEEK!
15
~s
tso
RW/SEEK Setup
to
LCTIDIR 7
~s
tos
RW/SEEK Hold from LCT/DIR
30
~s
tOST
LCT/DIR Setup to FRISTEP! 1
~s
tSTO
LCT/DIR Hold from FA/STEP!
24
~s
8MHz
clock
tSTU
DS
O
,1
Hold from FA/Step! 5
~s
tSTP
STEP Active Time
(H
igh)
5
~s
tsc
STEP
Cycle Time 33
~s
Note 3
tFR
FAULT
RESET
Active Time (High) 8
10
~s
tlO
X
INDEX Pulse Width
625
~s
tTC
Terminal Count Width
1
tCY
NOTES:
1.
Typical values for
TA
=
25'C
and nominal supply voltage.
2.
The former values are used
for
standard floppy and the
lalter
values are used for mini-floppies.
3.
tsc=
33~s
min. Is for different drive units. In the case
of
same unit,
tsc
can be ranged from 1 ms
to
16ms
with
8MHzclock
period, and
2ms
to
32ms
with 4 MHz
clock, under software control.
9-64