Data Width Codes: Byte, Word, And Long Word - ZiLOG System 8000 Hardware Reference Manual

HRM Zilog HRM
Table 4-2 ZBI status Lines, Transaction Coding:
S4
S3 S2 S1 SO TRANSACTION
0 0 0
0 0
Internal operation
0 0 0
0
1
Memory refresh
0
0 0
1 0
I/O reference
0 0
0 1
1
Special I/O reference
0 0
1 0
0
Segment trap acknowledge
0
0 1 0 1 INT
1
Interrupt acknowledge
0 0
1 1
0
INT 3 Interrupt acknowledge
0 0
1
1
1
INT 2 Interrupt acknowledge
0
1
0 0
0
Data memory request
0
1
0 0
1
Stack memory request
0
1
0
1
0
Transfer between data memory and an EPU
0
1
0 1
1
Transfer between stack memor'y and an EPU
0
1
1 0 0
Program reference, nth
cycle~
0 1
1
0 1
Program reference, 1st c yc Ie
0 1 1
1
0 Transfer between CPU and EPU
0
1 1 1 1
Reserved
1
X X
X X
Reserved
Table 11-3 Data Width Codes: Byte, Word, and Long Word
B/W\
W/LW
DATA WIDTH
Sets the' data width to byte
width,
8
bits, data on lines
AD<7:0>
0 Sets data width to word size,
16
bits, data on lines AD<15:0>
0
Sets data width to double-word
size, 3
r
,
bits, data on lines
c..
AD<31 : 0)-
0 0 Reservec,
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