Intel 8253 - Table 7-2 B Timing Requirements of the Execution Unit; Table 7-2 C Other AC Parameters

Intel387
TM
SX MATH COPROCESSOR
Table 7-2b. Timing Requirements of the Execution Unit (Asynchronous Mode CKM
e
0)
Pin Symbol Parameter
16 MHz–
33 MHz
Conditions
Test Refer to
Figure
25 MHz
Min Max Min Max
(ns) (ns) (ns) (ns)
NUMCLK2 t1 Period 20 500 15 500 2.0V 7.2
NUMCLK2 t2a High Time 6 6.25 2.0V
NUMCLK2 t2b High Time 3 4.5 V
CC
b
0.8V
NUMCLK2 t3a Low Time 6 6.25 2.0V
NUMCLK2 t3b Low Time 4 4.5 0.8V
NUMCLK2 t4 Fall Time 7 6 From V
CC
b
0.8V to 0.8V
NUMCLK2 t5 Rise Time 7 6 From 0.8V to V
CC
b
0.8V
NUMCLK2/ Ratio 10/16 14/10 10/16 14/10
CPUCLK2
NOTE:
If not used (CKM
e
1) tie NUMCLK2 low.
Table 7-2c. Other A.C. Parameters
Pin Symbol Parameter Min Max Units
RESETIN t30 Duration 40 NUMCLK2
RESETIN t31 RESETIN Inactive to 1st 50 NUMCLK2
Opcode Write
BUSY
Ý
t32 Duration 6 CPUCLK2
BUSY
Ý
, ERROR
Ý
t33 ERROR
Ý
(In)Active to 6 CPUCLK2
BUSY
Ý
Inactive
PEREQ, ERROR
Ý
t34 PEREQ Inactive to 6 CPUCLK2
ERROR
Ý
Active
READY
Ý
, BUSY
Ý
t35 READY
Ý
Active to BUSY
Ý
0 4 CPUCLK2
Active
READY
Ý
t36 Minimum Time from 4 CPUCLK2
Opcode Write to
Opcode/Operand Write
READY
Ý
t37 Minimum Time from 4 CPUCLK2
Operand Write to Operand
Write
36
36