Classic Computer Magazine Archive-Program Listing

PROGRAM LISTING: 85-04/PBI.M65

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%X; Parallel Device Handler ExampleX; By Earl RiceX; ANTIC Magazine(X;25X;(ASM,,#D:MYFILE.OBJ) because the obj code is put<%X;where there is no RAM available.FFPX;  EQUATESZ9†PDVMSKG;;Parallel device mask (indicates which ared9†PDIMSKI;;Parallel interrupt mask (not used in thisn-…GPDVVä;;Generic Parallel Device VectorxX;‚$†HATABS;;Device handler tableŒ)†CRITICB;;Critical code section flag–X; 3†DEVNAM
T;;Device name, E.G. T for "Telephone".ª$…HWGETÑ;;Hardware GET register´%…HWPUTÑ;;Hardware PUT register.¾5†HWRSETÑ;;Hardware reset (clears get register).È)†HWSTATÑ;;Hardware STATUS register.ÒX;ÜØæX; Rom vector tableð	;;Optional ROM checksumú ;;Optional Revision number€;;Mandatory ID number;;Optional Name or Type4!†NONEED;;Lo-level IO vector, which we don't need"5!†NONEED;;IRQ handler vector, which we don't need.,‘;;Mandatory ID number6†DEVNAM;;Device name@1	†NONEED;;Open vector, which we don't need.J2	†NONEED;;CLOSE vector, which we don't need.T 	†GETBYT;;GET BYTE vector.^ 	†PUTBYT;;PUT BYTE vector.h"	†GETSTA;;GET STATUS vector.r4	†NONEED;;SPECIAL vector, which we don't need.|,!„INIT;;INIT vector at power up or reset.†;;NOT USED.X;šX;CODE STARTS HERE¤X;®)X;Initialize device and device handler¸„INITÂ%Q†PDVMSK;;Get enabled device flagsÌL>;;Set bit 0.ÖP†PDVMSK;;& replace.à:X;Note: if device used interrupts we would set bit 0 ofêX;ô,X;Put device name in Handler table HATABSþ$>X;        Top of loop
†SEARCH#Q†HATABS9;;Get a byte from table&#F…FNDIT;;0? Then we found space.02:2D2N(>$;;Length of HATABSXD†SEARCH;;Still lookingb/:;;No room in HATABS; device not initializedlX;vX;         We found a spot.€	…FNDITŠQ>†DEVNAM;;Get device name.”#P†HATABS9;;Put it in blank spot.ž2¨&Q>…GPDVVÿ;;Get lo byte of vector.²'Q>…GPDVV;;Get hi byte of vector.¼P†HATABS9Æ:ÐX;ÚX; GET BYTE routine.ä
†GETBYTîQ>ø-P†CRITIC;;Enable deferred  vertical blank.%Q…HWGET;;Get a byte from hardware.P†HWRSET;;Reset hardware.;;;Indicate we handled it. :*X;4X; PUT BYTE routine.>
†PUTBYTH$>R-&†CRITIC;;Enable deferred  vertical blank.\!P…HWPUT;;Put byte to hardware.f;;;Indicate we handled it.p:zX;„X; GET STATUS routine.Ž
†GETSTA˜Q>¢-P†CRITIC;;Enable deferred  vertical blank.¬Q†HWSTAT;;Get HW status.¶;;;Indicate we handled it.À:ÊX;ÔX; Do nothing routine.Þ
†NONEEDè;;;Indicate we handled it.ò:üX;X;
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