inter80386

CYCLE 1 I CYCLE 2 I IDLE NON-PIPELINED NON-PIPELINED

(WRITE)(HALT)

T1

T2

T1

T2

Ti

Ti

Ti

Ti

CLK2 [

(82384 CLK) [

BEO~ BEl" BE3"[ MilO" W/R#

BE2#, A2-A31, [

O/C#

ADS#[

NA#[

READY# [

'rr-:":,~:-:--+:,-+---bV'\.ml::7o;",,od- 80386 REMAINS HALTED

UNTIL INTR, NMI OR ~"-lo"-..lj'-l"-lo"-~t-RESET IS ASSERTED.

I I

""",",,~-""'i"'--+a;..;..;....;,,;+...;.;..;;,.;,;;f->'~~f->"~"-t- 80386 RESPONDS TO

,--- i --- t --- t - HOLD INPUT WHILE IN THE HALT STATE.

LOCK#[

 

00-031 [

- (FLOATING) - - --

I I

231630-27

Figure 5-23.Halt Indication Cycle

The LOCK # output is asserted from the beginning of the first interrupt acknowledge cycle until the end of the second interrupt acknowledge cycle. Four idle bus states, Ti, are inserted by the 80386 between the two interrupt acknowledge cycles, allowing at least 160 ns of locked idle time for future 80386 speed selections up to 24 MHz (CLK2 up to 48 MHz), for compatibility with spec TRHRL of the 8259A Interrupt Controller.

During both interrupt acknowledge cycles, 00-031 float. No data is read at the end of the first interrupt acknowledge cycle. At the end of the second inter- rupt acknowledge cycle, the 80386 will read an ex- ternal interrupt vector from 00-07 of the data bus. The vector indicates the specific interrupt number (from 0-255) requiring service.

5.4.5 Halt Indication Cycle

The 80386 halts as a result of executing a HALT instruction. Signaling its entrance into the halt state, a halt indication cycle is performed. The halt indica- tion cycle is identified by the state of the bus defini- tion signals shown in 5.2.5 Bus Cycle Definition and a byte address of 2. BEO# and BE2# are the only signals distinguishing halt indication from shut- down indication, which drives an address of O. Dur- ing the halt cycle undefined data is driven on 00-031. The halt indication cycle must be acknowl- edged by READY # asserted.

A halted 80386 resumes execution when INTR (if interrupts are enabled) or NMI or RESET is assert- ed.

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Intel 80386 manual Halt Indication Cycle