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Esercizio esame DMAC. I/O AB I/O DB I/O CB Dec SELECT START IRQ SCO R Q S Q STATUS STARTDEV COMPLETE CLEAR IVN CPU IACK IN IACK OUT IRQ IOWR REG COUNTER.

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Presentation on theme: "Esercizio esame DMAC. I/O AB I/O DB I/O CB Dec SELECT START IRQ SCO R Q S Q STATUS STARTDEV COMPLETE CLEAR IVN CPU IACK IN IACK OUT IRQ IOWR REG COUNTER."— Presentation transcript:

1 Esercizio esame DMAC

2 I/O AB I/O DB I/O CB Dec SELECT START IRQ SCO R Q S Q STATUS STARTDEV COMPLETE CLEAR IVN CPU IACK IN IACK OUT IRQ IOWR REG COUNTER DEC TC R Q S Q IM SETIMCLRIM LD OR Interfaccia del DEVICE (timer)

3 I/O DB I/O CB SELECT REG I/O RD CPU I/O WR RESET I/O AB Termometro Interfaccia DEV_TEMP

4 Logica dell’interfaccia del DMAC per le interruzioni I/O AB I/O DB I/O CB Decoder SELECT START STARTD O.C. IRQ SCO DMAC R Q S Q STATUS STARTDEV COMPLETE CLEAR IVN CPU IACK IN IACK OUT IRQ

5 PD32 DB CB I/O DB I/O CB I/O AB MEMORIA SELECT I/O WR CAR INC WC I/O WR SCO DMAC DECR TC MBR F/F Q O.C. MBR MBG SCO VIDEO DATO SCRITTO NEXT DATO REG VIDEOREG MRD 32 bit STATUS F/F AB IRQ LD

6 Inizializzazione timer ; subroutine di inizializzazione parametrica, richiede il caricamento in R0 del numero ;di millisecondi dell’intervallo init:outb R0, DEVICE start DEVICE ret

7 Driver timer DRIVER 1,600h PUSH R0 INB DEVTEMP, R0 CMPB R0,#40 JN N_EQ_1 N_EQ_0:JNV NV_EQ JMP NV_DIF N_EQ_1:JV NV_EQ JMP NV_DIF NV_EQ: START DEVICE POP R0 RTI NV_DIF: CLRIM DEVICE OUT #512, WCOUNTER; inizializza il WCOUNTER OUT #BBBBh,CAR; passa il valore al CAR START DMAC;avvia trasferimento POP R0 RTI

8 Driver DMAC DRIVER 2,700h SETIM DEVICE START DEVICE CLEAR DMAC RTI


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