03.01.2015 Views

80C186EC/80C188EC Microprocessor User's Manual

80C186EC/80C188EC Microprocessor User's Manual

80C186EC/80C188EC Microprocessor User's Manual

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

BUS INTERFACE UNIT<br />

CLKOUT<br />

ALE<br />

T4<br />

T1 T2 T3 T4 T1 T2 T3 TI TI TI TI<br />

S2:0<br />

Valid Status<br />

Valid Status<br />

AD15:0<br />

[AD7:0]<br />

Addr<br />

Addr<br />

Valid Data<br />

[A15:8]<br />

Note<br />

Address<br />

Address<br />

A19:16<br />

Note<br />

Addr<br />

8H<br />

Addr<br />

8H<br />

BHE<br />

[RFSH=1]<br />

Note Valid Valid<br />

NOTE: Drives previous bus cycle value<br />

A1090-0A<br />

Figure 3-28. Returning to HALT After a DMA Bus Cycle<br />

3.5.6 Exiting HALT<br />

Any NMI or maskable interrupt forces the BIU to exit the HALT bus state (in any power management<br />

mode). The first bus operations to occur after exiting HALT are read cycles to reload the<br />

CS:IP registers. Figure 3-29 and Figure 3-30 show how the HALT bus state is exited when an<br />

NMI or INTn occurs.<br />

3-34

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!