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https://github.com/EranMorkon/AMTS.git
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43 lines
2.4 KiB
ArmAsm
43 lines
2.4 KiB
ArmAsm
;******************************************************************************
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;* Z80 Assembler program *
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;* Josef Reisinger *
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;* josef.reisinger@htl-hl.ac.at *
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;* 26/04/2015 *
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;******************************************************************************
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; ---------------------------- PIO 82C55 I/O ---------------------------------
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PIO_A: EQU $80 ; (INPUT)
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PIO_B: EQU $81 ; (OUTPUT) OUT TO LEDS
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PIO_C: EQU $82 ; (INPUT) IN from DIP SWITCHES
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PIO_CON: EQU $83 ; CONTROL BYTE PIO 82C55
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; --------------------------- CTC Z80 Timer Counter --------------------------
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CTC0 EQU $00 ; Channel 0
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CTC1 EQU $01 ; Channel 1
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CTC2 EQU $02 ; Channel 2
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CTC3 EQU $03 ; Channel 3
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; -------------------------- SIO (USART) ----------------------------------------
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SIO_A_D: EQU $40 ; Channel A Data Register
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SIO_B_D: EQU $41 ; Channel B Data Register
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SIO_A_C: EQU $42 ; Channel A Control Register
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SIO_B_C: EQU $43 ; Channel B Control Register
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;-------------------------- CONSTANTS ----------------------------------------
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RAMTOP: EQU $FFFF ; 32Kb RAM 8000H-FFFFH
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;******************************************************************************
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;* START AFTER RESET, *
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;* Function....: ready system and restart *
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;******************************************************************************
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ORG $0000
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DI ; Disable interrupt
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LD SP,RAMTOP ; Set stack pointer to top off ram
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LD A,$15 ; Configure CTC Channel 0:No Interrupt, Timer Mode, No Prescaler,
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OUT (CTC0),A ; trigger on positive edge, next word = time constant, Channel continuous result operation
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LD A,186 ; Write Time constant 186*560ns= 104µs
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OUT (CTC0),A
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AGAIN: IN A,(CTC0) ; Read actual status of CTC Channel 0
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JP AGAIN ; Endlos
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