[Coco] more 1 bit madness

[Allen Huffman]

On Jan 19, 2014, at 5:41 PM, Steve <6809er at srbsoftware.com> wrote:
> I took look at the code that Simon just posted today and it could never be used while a game is running.  The CPU overhead is just too much.

Grumble. I was afraid that might be the case.

I believe Grabber, the only CoCo 1 game I ever saw with real background music, was simply at a slow enough frame rate is was doing the tiny "beep" then animating then the "beep" again. That may explain why no more ambitious games did it.

The only other thing I ever saw on the CoCo 1 with background audio was a game called ZONX that appeared in Rainbow as a type-in assembly program. Oh, and here is is on YouTube. Geez. If you've never seen ZONX, check it out.
 
http://www.youtube.com/watch?v=Vuc6ADXtgeY

I remember typing this in! It had several types of sci fi noise audio in the background

When I first learned about the IRQ, I remember doing something in ROMPAK EDTASM that would hook in to the IRQ (which one? I didn't know back then I bet!), and then it would hit the POKE 140,X value (I think), and CLRB (or set it to 1?) then brach to 45543. That would make a blip noise. It would then increment. So it made a tone that went low to high, low to high, in the background, and I could type in BASIC. I guess I should have played with this more.

There are very few things still stuck in my head. THis is one:

0 POKE140,A:EXEC43345:A=A+1:GOTO0

(Line 0 'cause it's faster to go to that line, and A starts out at 0 when you run.) That's kinda what it was doing in the background with the IRQ.

About the only other thing I can still remember is something like

START	LDX #$400
LOOP 	INC  ,X+
		CMPX #$4FF
		BLE  LOOP
		BRA START

...though I forget the end of the screen location. And I bet this could be done more efficiently today. Assuming I even have the syntax correct. Er, "A/IM/AO/WE" or something to build. Then Z, and G START to run? I dunno. Been awhile.

Anyone ever found the Grabber author?
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Allen Huffman - PO Box 22031 - Clive IA 50325 - 515-999-0227 (vmail/TXT only)
Sub-Etha Software - http://www.subethasoftware.com - Established 1990!
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