Tandy 1000
Technical Reference Manual
8255A18255A·5
ABSOLUTE MAXIMUM RATINGS·
Ambient
TemperatlHL'
Under
Bias
Storage
Tt~mperalLJre
Voltage on
Any
Pin
With
Respect
to
Ground
Power
DisSlflation
o C
10
70 C
65
C
II)
'150
C
o 5V
to'
7V
1
Wdll
'NOTlCE:
Stresses
above
those
listed
under
"Absolute
MaXimum
RatlOgs"
may
cause
permanent
damage
to
the
deVice. This is a
stress
rating
only
and
functIOnal
opera-
tion
of
the
deVice
at
these
or
any
other
conditions
above
those
Indicated
In
the
operatIOnal
sectIOns
of
this
specifi-
cation
IS
not
Implied
Exposure
to
absolute
maximum
rating
eondllions
for
extended
pertods
may
affect
device
reliability
• 5V
'10%.
GND
OV) .
Max.
Unit Test Conditions
0.8
V
-------
Vee
V
----
0.45
•
V
IOl
2.5mA
0.45'
V
IOl
1.7mA
V
IOH
-40011A
V
IOH
- -20011A
-4.0
mA
R
EXT
75OU, V
EX1
'
1.5V
--------
120
mA
'10
I1A
V
,N
Vee
to
OV
--_.-
'10
I1
A
VOUT
Vee
to
45V
--~--
.-
IOF
l
Output
Float
Leakage
III
Input
Load
Current
ICC
Power
Supply
Currenl
IOAR
"1
Darlington
Drive
Currenl
-1.0
VoHIPERI
Output
High
Voltage (Peripheral Port I 2.4
VOH(DBI
Output
High Voltage (Data Bus)
24
VoLlPER)
Output
Low
Voltage (Peripheral
Portl
VOL
(DB)
Output
Low
Voltage (Data Busl
Symbol
Parameter
Min.
f------t--------------------i------+----+--I------
V,l
Input
Low
Voltage
-0.5
V'H
Input
High
Voltage 2.0
D.C, CHARACTERISTICS (TA C 0 C
to
70 C.
Vee
NOTE:
1.
Available on any 8 pins trom Port
Band
C
A.C. CHARACTERISTICS (TA
~
O'C
to
70C.
Vee
'5V'
10%,
GND
OV)'
Bus Parameters
READ
8255A
8255A5
___
'
Symbol
Parameter
Min.
Max. Min.
Max.
Unit
tAR
Address Stable Before
READ
0
0
ns
tRA
Address Stable
After
READ
0
0
ns
t'1R
READ
Pulse
Width
300 300
ns
tRO
Data
Valid
From
R EAD" I
250
200
ns
tOF
Data
Float
After
READ
10
150
10
100
ns
IRV
Time
Between
READs
and/or
WR
IT
Es
850 850
ns
6-182
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