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Z8018x
Family MPU User Manual
86
Last MC
Phi
INT1,2
–
A0
A19
M1
MREQ
IORQ
RD
WR
–
D0
D7
ST
MC: Machine Cycle
Dynamic RAM Refresh Control
UM005004-0918
INT1, INT2, internal interrupt acknowledge cycle
T1
T2
TW*
TW*
T3
Ti
T1
PC
Figure 43.
INT1, INT2 and Internal Interrupts Timing Diagram
The Z8X180 incorporates a dynamic RAM refresh control circuit
including 8-bit refresh address generation and programmable refresh
timing. This circuit generates asynchronous refresh cycles inserted at the
programmable interval independent of CPU program execution. For
systems which do not use dynamic RAM, the refresh function can be
disabled.
When the internal refresh controller determines that a refresh cycle should
occur, the current instruction is interrupted at the first breakpoint between
machine cycles. The refresh cycle is inserted by placing the refresh
address on A0–A7 and the RFSH output is driven Low.
PC Stacking
T2
T3
T1
T2
T3
T1
T2
SP-2
Vector
SP-1
PCH
PCL
* Two Wait States are automatically inserted.
Op Code
fetch cycle
Vector Table Read
T3
T1
T2
T3
T1
T2
Starting
Address
Vector+1
Starting
Starting
address (L)
address (H)
T3
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Questions and answers
are there a timing diagrams for PUSH and POP instructions?
The timing diagrams for the PUSH and POP instructions for the ZiLOG Z8018 Series are as follows:
POP Instruction (e.g., POP IX or POP IY):
- Machine Cycle 1 (MC1): Fetch POP opcode.
- Machine Cycle 2 (MC2): Fetch address code.
- Machine Cycle 3 (MC3): Read from memory at SP (Stack Pointer); data goes to low byte (e.g., IXL or IYL).
- Machine Cycle 4 (MC4): Read from memory at SP+1; data goes to high byte (e.g., IXH or IYH).
PUSH Instruction (e.g., PUSH IX or PUSH IY):
- Machine Cycle 1 (MC1): Fetch PUSH opcode.
- Machine Cycle 2 (MC2): Fetch address code.
- Machine Cycle 3 (MC3): Decrement SP by 1 and write high byte (e.g., IXH or IYH) to memory at SP.
- Machine Cycle 4 (MC4): Decrement SP by 1 and write low byte (e.g., IXL or IYL) to memory at SP.
Each machine cycle includes three T-states (T1, T2, T3), and memory control signals (such as MREQ, RD, WR) are active as needed during these cycles.
This answer is automatically generated