Tandy
1000
intJ
8255AJ8255A·5
Technical
Reference
Manual
A.C. CHARACTERISTICS (Continued)
WRITE
8255A
8255A-5
Symbol Parameter
Min.
Max.
Min. Max.
Unit
tAW
Address Stable Before
WR
IT E 0
0
ns
tWA
Address Stable
After
WR
ITE
20
20
ns
tww
WRITE
Pulse
Width
400
300
ns
tDw
Data
Valid
to
WR
ITE
IT.
E)
100
100
ns
tWD
Data
Va
lid
After
WR
I
TE
30
30
ns
OTHER
TIMINGS
8255A
8255A-5
Symbol Parameter
Min.
Max.
Min.
Max.
Unit
tWB
WR
~
1
to
Output
lll
350
350
ns
tlR
Peripheral Data Before RD
0
0
ns
tHR
Peripheral Data
After
RD
0 0
ns
tAK
ACK
Pulse
Width
300
300
ns
tST
STB
Pulse
Width
500
500
ns
IpS
Per.
Data Before T.E.
of
STB 0 0
ns
tpH
Per. Data
After
T.E.
of
STB 180
100
ns
tAD
ACK
= 0
to
Output
lll
300
300
ns
tKD
ACK
.-
1
to
Output
Float
20
250 20
250
ns
tWOB
WR
= 1
to
0 BF = 0
111
650
650
ns
tAOB
ACK
= 0
to
OBF =
11
1
1
350
350
ns
tSIB
ST
B = 0
to
IBF = 1
11
I
300
300
ns
t
RIB
RD=
1
to
IBF
=0
111
300
300
ns
tRIT
R0
= 0
to
INTR = 01' I
400
400
ns
tSIT
STB = 1
to
INTR
= 1
111
300 300
ns
tArT
ACK
= 1
to
INTR
= 1
111
350
350
ns
tWIT
WR
~
Oto
INTR
=
011.31
450
450
ns
NOTES:
1.
Test
Conditions C
L
=
150
pF.
2.
Period
of
Reset pulse must
be
at least
50ILs
during
or
after power on. Subsequent Reset pulse can
be
500
ns
min
3.
INTRf may occur
as
early
as
WRt
• For Extended Temperature EXPRESS.
use
M8255A electrical parameters
A.C. TESTING INPUT, OUTPUT WAVEFORM
>TEST
POINTS
<
A.C. TESTING LOAD CIRCUIT
'V
EX
TIS SET A
r'VAAIOUS
VOL
rAGES
DuRING
TESTING
TO
GuARANTEE THE
SPECIFICATION
6-183
AFN·OO7
....C
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