Trs-80 COCO help.....Random Routine help....

[GreenDayRlz]

I`m making a game, and where do I store the #`s to get the random routine to "randomize" them?

 

And wherwe does it put them?

 

I`m doing this for my game, asteroids.

 

 

 

 

After I make this, I`m gona make the tron game...That`ll be kinda boring, but fun.......?(lol)

Edited June 19, 2008 by GreenDayRlz

[Bruce Tomlin]

Here's a random routine from when I did a CoCo Infocom Interpreter back in '84. It looks like it returns the random number in X. I probably translated this from Infocom's Z80 random number routine.

 

RNDSEED:FDB	 0,0
. . .
	LDD	 #$FFFF
	STD	 RNDSEED
	STD	 RNDSEED+2
	LDB	 #5
INIT6:  JSR	 RANDOM
	DECB
	BNE	 INIT6
. . .
RANDOM: PSHS	D
	LDB	 #2
RANDOM1:PSHS	B
	LDX	 #RNDSEED
	LDA	 ,X
	SEC
	LDB	 #8
RANDOM2:PSHS	B
	ROLA
	ROLA
	ROLA
	EORA	,X
	ROLA
	ROLA
	LDX	 #RNDSEED
	ROL	 ,X+
	ROL	 ,X+
	ROL	 ,X+
	ROL	 ,X
	PULS	B
	DECB
	BNE	 RANDOM2
	PULS	B
	DECB
	BNE	 RANDOM1
	LDX	 RNDSEED+2
	PULS	D,PC

To randomize, you could just call it at every refresh (especially during title screens), and then user input should give you some randomness.

 

You also might find my debugger useful too. (and here with some comments added to the code)

[Thomas Jentzsch]

Have a look at LFSRs. Those are great for random numbers and result into very compact code (less than 10 instructions for an 8-bit LFSR).

 

They have been discussed in the Atari 2600 programming forums.

[Heaven/TQA]

am using this for my A8 game, it's predictable so you have to feed a starting seed into it:

 

_get_Random: 
_rand	inc	 rnd2
	lda	 rnd2
	clc
	adc	 rnd1
	adc	 rnd2
	sta	 rnd1
	eor	 rnd2
	sta	 rnd2
	sbc	 rnd0
	sta	 rnd0
	rts

rnd0	dta 0
rnd1	dta 0
rnd2	dta 0

[GreenDayRlz]

I don`t have edtasm...I have something from disk put onto my computer. Special hacked by my dads friend "edition". Custome burned on rom...anyone have non edtasm instructions?

 

 

EDIT:

 

I would like just to use the COCO`s, since it`s pretty random.....I`ve never been able to guess it in basic.....Lol. I`ve spent too much time on basic....I like 6809 beter. It makes it alot easier, except when you put in LBEQ 3200, it says error and you have to just put in beq 3200.....I`ve ruined a couple of re-writes that way...

Edited June 19, 2008 by GreenDayRlz

[Bruce Tomlin]

am using this for my A8 game, it's predictable so you have to feed a starting seed into it:

...except that the CoCo doesn't use a 6502.

[Bruce Tomlin]

I would like just to use the COCO`s, since it`s pretty random.....I`ve never been able to guess it in basic.....Lol. I`ve spent too much time on basic....I like 6809 beter. MONDEB makes it alot easier, except when you put in LBEQ 3200, it says error and you have to just put in beq 3200.....I`ve ruined a couple of re-writes that way...

Are you talking about calling the BASIC routines from assembly language (it's not quite trivial) or just how to use it in BASIC?

 

If you're just talking about using it from BASIC, I'll have to look up a disassembly to see where the random seed is, but there's nothing like a clock chip that you could use to initialize it.

[GreenDayRlz]

We printed off this book called Extended Color Basic Unraveled. I have the code. I could RTS back to basic and do the RND`S there, and jump back into The 6809.....Just a thought.

 

 

I`m doing it in 6809 assembly through mondeb. Lol, so please don`t give me edtasm things.....Edtasm is easier, but I like the from scratch method......But it takes alot of my paper.......

[Heaven/TQA]

Bryan... but I guess that my random routine is so basic that it could be transfered to 6809 very easily? or does the 6809 do not offer eor and rol???

[GreenDayRlz]

I`m 99.9% Sure it offers both.

 

 

I`m sorry it took so long for reply, my modem went into retirement.

 

 

I found the RND routine in a book called either Color Basic Unravelled or entended unravveled, same book allmost.

 

The routine starts at B1F1 in a EXTENDED Basic ROM. The seeds are just below it.