Motorola M6800 manual Reset Sequence

Page 16

MPU-16

RESET SEQUENCE

1.While HALT is high, RESET goes low for at least eight cycles of Øl, Ø2 during which all internal registers are cleared and interrupt bit (I) in CC is set.

2.Data at FFFE loads into PCH.

3.Data at FFFF loads into PCL.

4.PC contents go out on ADRS bus during Øl.

5.Contents of cell addressed enters instruction register during and is decoded as first instruction.

6.If two or more byte instruction, additional bytes enter MPU for execution. If not, go to next step.

7.After execution, step 5 is repeated for subsequent instructions.

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Contents MPU-1 Introduction MPU-2 MPU-3 MPU-4 MPU-5 BIT N0 Function MPU-7 Data BUS Enabledbe MPU-8READ/WRITE R/W Valid Memory AddressvmaMPU-9 NON-MASKABLE InterruptnmiBUS Available BA THREE-STATE Control TSC Address BUS AO/A15ABA INSADC INXPage MPU-14 Summary of MPU Operation Reset Sequence IRQ Sequence NMI Sequence RTI ExecutionSWI Instruction Page Page Page Page Page Page Page Page