Z80181 Zilog., Z80181 Datasheet - Page 10

• Manufacturer Part Number: Z80181
• Description: SMART ACCESS CONTROLLER (SAC)
• Manufacturer: Zilog.

Zilog
SYSTEM CONTROL SIGNALS
Pin Name
ST
2-10
Pin Number
3
Input/Output, Tri-State
Out, Active 1
Function
Status. This signal is used with the /M1 and /HALT output
to decode the status of the CPU machine cycle. Note that
the /M1 output is affected by the status of the M1E bit in the
OMCR register. The following table shows
the status while M1E=1.
ST
0
1
1
0
0
1
/HALT
1
1
1
X
0
0
/M1
0
0
1
1
0
1
Operation
CPU Operation
(1st Opcode fetch)
CPU Operation
(2nd and 3rd Opcode fetch)
CPU Operation
(MC other than Opcode fetch)
DMA operation
HALT mode
SLEEP mode
(Incl. System STOP mode)
S
MART
A
CCESS
C
DS971800500
ONTROLLER
Z80181
SAC
™