Normally Ready System Timings - Intel 80C186XL User Manual

CLKOUT
ARDY
In a Normally-Ready system, a wait state will be inserted when 1 & 2 are met.
(Assumes SRDY is low.)
1. T ARYCH : ARDY low to clock high
2. T ARYCHL : Clock high to ARDY high (ARDY inactive hold time)
CLKOUT
ARDY
SRDY
Alternatively, in a Normally-Ready system, a wait state will be inserted
when1 & 2 are met for SRDY and ARDY.
1. T ARYCL , T SRYCL : ARDY and SRDY low to clock low
2. T CHARX , T CLSRY : ARDY and SRDY low from clock low
Failure to meet ARDY and SRDY setup and hold can cause a device failure
!
(i.e., the bus hangs or operates inappropriately).
Conditions causing the BIU to become idle include the following.
•
The instruction prefetch queue is full.
•
An effective address calculation is in progress.
•
The bus cycle inherently requires idle states (e.g., interrupt acknowledge, locked opera-
tions).
•
Instruction execution forces idle states (e.g., HLT, WAIT).
T2
2
1
T2
1
Figure 3-18. Normally Ready System Timings
BUS INTERFACE UNIT
T3 TW
T3 TW
2
T4
T4
A1512-0A
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