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198 lines
7.2 KiB
198 lines
7.2 KiB
;==================================================================================================
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; Z80 DMA DRIVER FOR ECB-DMA
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;==================================================================================================
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;
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; DUE TO LOW CLOCK SPEED CONTRAINTS OF Z80 DMA CHIP, THE HALF CLOCK FACILITY
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; IS USED DURING DMA PROGRAMMING AND CONTINUOUS BLOCK TRANSFERS.
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; TESTING CONDUCTED ON A SBC-V2-005 @ 10Mhz
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;
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DMA_CONTINUOUS .equ %10111101 ; + Pulse
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DMA_BYTE .equ %10011101 ; + Pulse
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DMA_BURST .equ %11011101 ; + Pulse
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DMA_LOAD .equ $cf ; %11001111
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DMA_ENABLE .equ $87 ; %10000111
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DMA_FORCE_READY .equ $b3
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DMA_DISABLE .equ $83
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;
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;DMA_RESET .equ $c3
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;DMA_RESET_PORT_A_TIMING .equ $c7
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;DMA_RESET_PORT_B_TIMING .equ $cb
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;DMA_CONTINUE .equ $d3
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;DMA_DISABLE_INTERUPTS .equ $af
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;DMA_ENABLE_INTERUPTS .equ $ab
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;DMA_RESET_DISABLE_INTERUPTS .equ $a3
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;DMA_ENABLE_AFTER_RETI .equ $b7
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;DMA_READ_STATUS_BYTE .equ $bf
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;DMA_REINIT_STATUS_BYTE .equ $8b
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;DMA_START_READ_SEQUENCE .equ $a7
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;DMA_WRITE_REGISTER_COMMAND .equ $bb
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;
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;==================================================================================================
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; DMA INITIALIZATION CODE
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;==================================================================================================
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;
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DMA_INIT:
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CALL NEWLINE
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PRTS("DMA: IO=0x$")
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LD A, DMABASE
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CALL PRTHEXBYTE
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;
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ld a,0
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out (DMABASE+1),a ; force ready off
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;
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ld hl,DMACode ; program the
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ld b,DMACode_Len ; dma command
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ld c,DMABASE ; block
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;
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ld a,(RTCVAL)
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or %00001000 ; half
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out (112),a ; clock
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di
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otir ; load dma
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ei
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and %11110111 ; full
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out (112),a ; clock
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ret
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;
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DMACode ;.db DMA_DISABLE ; R6-Command Disable DMA
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.db %01111101 ; R0-Transfer mode, A -> B, start address, block length follow
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.dw 0 ; R0-Port A, Start address
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.dw 0 ; R0-Block length
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.db %00010100 ; R1-No timing bytes follow, address increments, is memory
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.db %00010000 ; R2-No timing bytes follow, address increments, is memory
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.db %10000000 ; R3-DMA, interrupt, stop on match disabled
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.db DMA_CONTINUOUS ; R4-Continuous mode, destination address, interrupt and control byte follow
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.dw 0 ; R4-Port B, Destination address
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.db %00001100 ; R4-Pulse byte follows, Pulse generated
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.db 0 ; R4-Pulse offset
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.db %10011010 ; R5-Stop on end of block, ce/wait multiplexed, READY active HIGH
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.db DMA_LOAD ; R6-Command Load
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; .db DMA_FORCE_READY ; R6-Command Force ready
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; .db DMA_ENABLE ; R6-Command Enable DMA
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DMACode_Len .equ $-DMACode
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;
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;==================================================================================================
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; DMA COPY BLOCK CODE - ASSUMES DMA PREINITIALIZED
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;==================================================================================================
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;
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DMALDIR:
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ld (DMASource),hl ; populate the dma
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ld (DMADest),de ; register template
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ld (DMALength),bc
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;
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ld hl,DMACopy ; program the
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ld b,DMACopy_Len ; dma command
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ld c,DMABASE ; block
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;
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ld a,(RTCVAL)
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or %00001000 ; half
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out (112),a ; clock
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di
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otir ; load and execute dma
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ei
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and %11110111 ; full
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out (112),a ; clock
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ret
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;
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DMACopy ;.db DMA_DISABLE ; R6-Command Disable DMA
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.db %01111101 ; R0-Transfer mode, A -> B, start address, block length follow
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DMASource .dw 0 ; R0-Port A, Start address
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DMALength .dw 0 ; R0-Block length
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.db %00010100 ; R1-No timing bytes follow, address increments, is memory
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.db %00010000 ; R2-No timing bytes follow, address increments, is memory
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.db %10000000 ; R3-DMA, interrupt, stop on match disabled
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.db DMA_CONTINUOUS ; R4-Continuous mode, destination address, interrupt and control byte follow
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DMADest .dw 0 ; R4-Port B, Destination address
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.db %00001100 ; R4-Pulse byte follows, Pulse generated
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.db 0 ; R4-Pulse offset
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; .db %10011010 ; R5-Stop on end of block, ce/wait multiplexed, READY active HIGH
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.db DMA_LOAD ; R6-Command Load
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.db DMA_FORCE_READY ; R6-Command Force ready
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.db DMA_ENABLE ; R6-Command Enable DMA
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DMACopy_Len .equ $-DMACopy
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;
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;==================================================================================================
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; DMA I/O OUT BLOCK CODE - ADDRESS TO I/O PORT
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;==================================================================================================
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;
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DMAOTIR:
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ld (DMAOutSource),hl ; populate the dma
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ld (DMAOutDest),a ; register template
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ld (DMAOutLength),bc
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;
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ld hl,DMAOutCode ; program the
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ld b,DMAOut_Len ; dma command
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ld c,DMABASE ; block
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;
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ld a,(RTCVAL)
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or %00001000 ; half
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out (112),a ; clock
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di
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otir ; load and execute dma
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ei
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and %11110111 ; full
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out (112),a ; clock
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ret
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;
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DMAOutCode ;.db DMA_DISABLE ; R6-Command Disable DMA
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.db %01111001 ; R0-Transfer mode, B -> A (temp), start address, block length follow
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DMAOutSource .dw 0 ; R0-Port A, Start address
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DMAOutLength .dw 0 ; R0-Block length
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.db %00010100 ; R1-No timing bytes follow, fixed incrementing address, is memory
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.db %00101000 ; R2-No timing bytes follow, address static, is i/o
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.db %10000000 ; R3-DMA, interrupt, stop on match disabled
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.db %10100101 ; R4-Continuous mode, destination port, interrupt and control byte follow
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DMAOutDest .db 0 ; R4-Port B, Destination port
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; .db %00001100 ; R4-Pulse byte follows, Pulse generated
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; .db 0 ; R4-Pulse offset
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.db %10011010 ; R5-Stop on end of block, ce/wait multiplexed, READY active HIGH
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.db DMA_LOAD ; R6-Command Load
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.db %00000101 ; R0-Port A is Source
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.db DMA_LOAD ; R6-Command Load
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.db DMA_FORCE_READY ; R6-Command Force ready
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.db DMA_ENABLE ; R6-Command Enable DMA
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DMAOut_Len .equ $-DMAOutCode
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;
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;==================================================================================================
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; DMA I/O INPUT BLOCK CODE - I/O PORT TO ADDRESS
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;==================================================================================================
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;
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DMAINIR:
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ld (DMAInDest),hl ; populate the dma
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ld (DMAInSource),a ; register template
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ld (DMAInLength),bc
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;
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ld hl,DMAInCode ; program the
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ld b,DMAIn_Len ; dma command
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ld c,DMABASE ; block
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;
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ld a,(RTCVAL)
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or %00001000 ; half
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out (112),a ; clock
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di
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otir ; load and execute dma
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ei
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and %11110111 ; full
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out (112),a ; clock
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ret
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;
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DMAInCode ;.db DMA_DISABLE ; R6-Command Disable DMA
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.db %01111001 ; R0-Transfer mode, B -> A, start address, block length follow
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DMAInDest .dw 0 ; R0-Port A, Start address
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DMAInLength .dw 0 ; R0-Block length
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.db %00010100 ; R1-No timing bytes follow, address increments, is memory
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.db %00111000 ; R2-No timing bytes follow, address static, is i/o
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.db %10000000 ; R3-DMA, interrupt, stop on match disabled
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.db %10100101 ; R4-Continuous mode, destination port, no interrupt, control byte.
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DMAInSource .db 0 ; R4-Port B, Destination port
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; .db %00001100 ; R4-Pulse byte follows, Pulse generated
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; .db 0 ; R4-Pulse offset
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.db %10011010 ; R5-Stop on end of block, ce/wait multiplexed, READY active HIGH
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.db DMA_LOAD ; R6-Command Load
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.db DMA_FORCE_READY ; R6-Command Force ready
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.db DMA_ENABLE ; R6-Command Enable DMA
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DMAIn_Len .equ $-DMAInCode
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