8255A18255A·5

 

 

DATA FROM

 

 

 

 

 

A 8080 TO 8255

 

 

 

 

 

\

 

 

_ t AOB _

 

 

\

j

 

 

i

/

 

~'WOB-~

 

 

INTR

\

 

- tAK -

~

 

 

\

 

,

/~k:'

1

 

 

 

 

 

 

 

, _ tsT - _

 

 

 

 

 

\

V

 

 

 

 

 

 

 

 

 

 

'SIB-Ii

 

 

 

rBF

 

 

... -

1-"01- -

 

 

----------

 

BUS

 

---

' •.1-_ - - - - i---

PERIPHERAL

 

 

 

 

 

 

 

 

/

_

tpHI---

/

__ tRIB

 

 

 

 

 

 

OATAInOM

 

OATA~OM

/

 

 

PERIPHERAL TO 8255

 

8255 TO PERIPHERAL

 

 

 

 

DATA FROM

8255 TO 8OBO

Figure 30. MODE 2 (Bidirectional)

NOTE: Any sequence where WR occurs before ACK and STB occurs before RD is permissible. (lNTR = IBF • MASK· STB • RD + OBF • MASK'ACK • WR )

9-37

AFN-00744A-21

Page 352
Image 352
Intel mcs-48 manual SIB-Ii