Instructables

Step 3: Implement it using the parallel port under DOS

Picture of Implement it using the parallel port under DOS
The 74 LS 123 is what I used to get the same system as the joystick port. It has two RMM. In the PDF file you can see the datasheet and a simple circuit to attach to your parallel port. I am a Qbasic fan (because it is widely available) so the code is written in it. The procedure is the same as in the VB sample:

LPTdata = &H378
LPTstatus = LPTdata + 1: LPTcontrol = LPTdata + 2

YMAXX = 500

SCREEN 2
LINE (9, 1)-(630, 170), , B, &H3333
VIEW (10, 2)-(629, 169)
WINDOW (0, YMAXX)-(620, 0)

MAXX = 620

DIM D(MAXX)

WHILE INKEY$ = ""
OUT LPTcontrol, &H1
OUT LPTcontrol, &H0
FOR Y = 1 TO YMAXX
IF (INP(LPTstatus) AND &H10) / &H10 = 1 THEN EXIT FOR
NEXT Y

LOCATE 23, 1
PRINT USING "####"; Y

LINE (0, 0)-(MAXX, YMAXX), 0, BF

FOR I = 1 TO MAXX
LINE (I, D(I - 1))-(I, D(I))
D(I - 1) = D(I)
NEXT I
D(MAXX) = Y

WEND

One output pin is used to Trigger the MMR and one input pin to read the output of it.
74ls123.pdf(610x784) 452 KB
 
Remove these adsRemove these ads by Signing Up