Typewriter User Manual

6- 44 MC68340 USER’S MANUAL MOTOROLA
***************************************************************************
* DMA Channel 1 equates
DMACH1 EQU $780 Offset from MBAR for channel 1 regs
DMAMCR1 EQU $0 MCR for channel 1
* Channel 1 register offsets from channel 1 base address
DMAINT1 EQU $4 interrupt register channel 1
DMACCR1 EQU $8 control register channel 1
DMACSR1 EQU $A status register channel 1
DMAFCR1 EQU $B function code register channel 1
DMASAR1 EQU $C source address register channel 1
DMADAR1 EQU $10 destination address register channel 1
DMABTC1 EQU $14 byte transfer count register channel 1
SARADD EQU $6001 source address is an ODD address
DARADD EQU $10000 destination address is and EVEN address
NUMBYTE EQU $14 number of bytes to transfer
***************************************************************************
***************************************************************************
* Initialize DMA Channel 1
***************************************************************************
LEA MODBASE+DMACH1,A0 Pointer to channel 1
* Initialize DMA channel 1 MCR
* Normal Operation, ignore FREEZE, dual-address mode. ISM field at 0. Make
* CPU32 SR I2-I0 bits are less than or equal to ISM bits for channel startup.
* Supervisor/user reg. unrestricted, MAID field at 4. IARB priority at 8.
MOVE.W #$00C8,(A0)
* Clear channel control reg.
* Clear STR (start) bit to prevent the channel from starting a transfer early.
CLR.W DMACCR1(A0)
* Initialize interrupt reg.
* Interrupt priority at 7, interrupt vector at $42.
MOVE.W #$0742,DMAINT1(A0)
* Initialize channel status reg.
* Clear the DONE, BES, BED, CONF and BRKP bits to allow channel to startup.
MOVE.B #$7C,DMACSR1(A0)
* Initialize function code reg.
* DMA space, supervisor data space for source and destination.
MOVE.B #$DD,DMAFCR1(A0)
* Initialize source operand address
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