Author Topic: Looking for a specific bouncing ball demo.  (Read 854 times)

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Offline blackdalek

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Looking for a specific bouncing ball demo.
« on: 13:04, 13 March 18 »
Back in the early late 80's I had a demo on a disc which I think was part programmed in BASIC with a small machine code routine.

First it slowly drew up what looked like an orange basket ball with the vertical "basket ball" segment lines, roughly the size of two thirds of the screen, then it proceeded to bounce the ball around the monitor while making a kind of rubber ball bouncing sound.

I think the trick in this demo was the ball itself was not animated, but the whole screen was being shunted around the monitor.

Does anyone know this of demo or remember the name for it?

It came with a load of pirated disks from some guy my Uncle knew in Papua New Guinea ;)
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Offline ervin

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Re: Looking for a specific bouncing ball demo.
« Reply #1 on: 13:07, 13 March 18 »
Could it be the program shown in this video?

https://www.youtube.com/watch?v=m9Go8cwSDzQ

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Offline johnno56

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Re: Looking for a specific bouncing ball demo.
« Reply #2 on: 13:44, 13 March 18 »
That brings back memories... Many thanks. :)

J

ps: This program, "Blitter", was a "Type-in" that appeared in Amstrad Action July 1986 page 77.
« Last Edit: 14:24, 13 March 18 by johnno56 »
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Offline blackdalek

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Re: Looking for a specific bouncing ball demo.
« Reply #3 on: 14:46, 13 March 18 »
That's not it, but.... it's almost identical in its execution.
The one I had did not use ink swapping and the ball was more like a basket ball. The sound was similar.
Also, the ball was larger and moved all the way to the edges of the monitor - not within the border. (The entire screen was being repositioned to give the movement effect. When you stopped the program the "Ready" prompt would be at an odd location because the whole screen was shifted out of whack).

I think that video could just be a modified version of the one I had (or I had the modified version).
« Last Edit: 14:51, 13 March 18 by blackdalek »
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Offline ComSoft6128

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Re: Looking for a specific bouncing ball demo.
« Reply #4 on: 14:50, 13 March 18 »
I have a 3.5" disk here full of small (3-4K) demo's from the Allan Scully PD library. I think this or something like it may be there. I will have a look at the weekend.

Cheers,

Peter

Offline blackdalek

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Re: Looking for a specific bouncing ball demo.
« Reply #5 on: 14:57, 13 March 18 »
I also have a stack of 5.25" floppies that came from PNG, one of which may still contain the demo in question. I still possess about 75% of those disks. I just can't remember which disk it was on or the file name.  :doh:
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Offline pelrun

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Re: Looking for a specific bouncing ball demo.
« Reply #6 on: 15:42, 13 March 18 »
I think I know exactly what you're referring to. I bet it was a type-in in The Amstrad User (the main aussie mag) as I remember playing with something very similar to what you describe. Big ball, white background, CRTC tricks to bounce it off the edges of the monitor and not just the screen area.


(I remember it so clearly because I then reimplemented it on the Beeb's at school...)

Offline pelrun

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Re: Looking for a specific bouncing ball demo.
« Reply #7 on: 15:57, 13 March 18 »
Found it:

http://www.cpcwiki.eu/index.php/File:TAU_30Page18.JPG
http://www.cpcwiki.eu/index.php/File:TAU_30Page19.JPG


Edit: actually, from the description this might just be the one posted earlier in the thread. Bit hard to tell without typing the whole thing in and testing it.
« Last Edit: 16:00, 13 March 18 by pelrun »

Offline johnno56

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Re: Looking for a specific bouncing ball demo.
« Reply #8 on: 16:51, 13 March 18 »
I beg to differ. The TAU and the ACU listings are exactly the same, except for a key definition statement (line 430 - ACU) that was not included in the TAU version. The title for both is "Blitter". Both were written by Paul Bond.

I have a pdf version of the ACU magazine and compared to the posted TAU images.

J

https://www.dropbox.com/s/gqct105m44r6pjz/acu.png?dl=raw  (I hope this works...)
« Last Edit: 17:04, 13 March 18 by johnno56 »
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Offline Johnny Olsen

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Re: Looking for a specific bouncing ball demo.
« Reply #9 on: 16:53, 13 March 18 »
It was also printed in Amstrad Action July 1986.
And is identical to Ervins video.

http://www.cpc-power.com/index.php?page=detail&num=9154

Offline blackdalek

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Re: Looking for a specific bouncing ball demo.
« Reply #10 on: 17:24, 13 March 18 »
You can all stop looking now. I've just gone through about 20 old disks and found it!
The filename was "bug.bas" and seems to be entirely basic with just some OUT and CALL commands to move the screen.
I have attached the file (hopefully).

Also during my search I found some sprite artwork I made many years ago for a soldier and Dalek which I thought were long since lost, but that is for another thread.
« Last Edit: 23:06, 13 March 18 by blackdalek »
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Offline pelrun

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Re: Looking for a specific bouncing ball demo.
« Reply #11 on: 18:06, 13 March 18 »
That's definitely the one I remember (there seems to be a spurious "SPC" in line 10 I had to remove to make it work though).


It's a ten-liner, so it might have been an ACU typein?

Offline Nich

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Re: Looking for a specific bouncing ball demo.
« Reply #12 on: 22:29, 13 March 18 »
It's a ten-liner, so it might have been an ACU typein?

It was published as a 10-liner in the May 1987 issue of Computing with the Amstrad, under the title 'Ball control'. Ian C. Sharpe is the author.

The ENV command in line 10 should read ENV 1,10,-1,2.

Offline johnno56

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Re: Looking for a specific bouncing ball demo.
« Reply #13 on: 22:31, 13 March 18 »
Ah yes. I remember this one. I recall how impressed I was that all that could be done in "10 lines".

Unfortunately, this program did not work, as there was an error in line 10. Seeing it was part of the "sounds" that were produced, I removed all the 'ent', 'env' and 'sound' statements. The program ran... up to a point. The ball 'shadow' was drawn. The ball was drawn. That seems to be all it does. I remember it 'bouncing' around the screen the last time I ran this program... (maybe 1987)

Is there another listing?

I too tried to run it after removing just the 'spc' but the 'ball' did not move...

I think I may have some 'dsk' images of 'typeins' somewhere. But I could be wrong...

J

ps: I located the program on one of my 'typein' dsk images. It was called 'bouncing.bas". The shadow and ball were drawn. The 'bouncing' sounds played. But the 'ball' did not move... I will try to paste the listing...

J

10 DEFINT a-z:ENV 1,10,-1,2:ENT 1,10,-60,2:r=160:s=r^2:DEG:PLOT 1000,1000,1
20 MODE 1:BORDER 26:INK 0,26:INK 1,0:INK 2,6:INK 3,15:ORIGIN 200,200
30 z=4:GOSUB 90:PLOT 1000,1000,2:ORIGIN 160,238:z=2:GOSUB 90:PLOT 1000,1000,3
40 FOR i=16 TO 160 STEP 24:GOSUB 100:NEXT:xd=1:yd=1:x=35:y=28
50 WHILE 1:OUT &BC00,2:CALL &BD19:OUT &BD00,x:OUT &BC00,7:OUT &BD00,y
60 y=y+yd:IF y=21 OR y=35 THEN yd=-yd:z=RND*800+600:SOUND 129,z,0,15,1,1:SOUND 132,z+10,0,15,1,1:GOTO 60
70 x=x+xd:IF x=22 OR x=50 THEN xd=-xd:SOUND 129,z,0,15,1,1:SOUND 132,z+10,0,15,1,1:GOTO 70
80 WEND
90 FOR y=0 TO r STEP z:x=SQR(s-y*y):MOVE x,y:DRAWR -2*x,0:MOVE x,-y:DRAWR-2*x,0:NEXT:RETURN
100 MOVE i,0:FOR a=0 TO 360 STEP 10:DRAW i*COS(a),r*SIN(a):NEXT:RETURN
« Last Edit: 22:53, 13 March 18 by johnno56 »
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Offline johnno56

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Re: Looking for a specific bouncing ball demo.
« Reply #14 on: 23:08, 13 March 18 »
Problem solved. It was my emulator!! Ran the program using JavaCPC and it ran flawlessly. Shadow drawn. Ball drawn. Ball bounced around. Sounds played. My apologies for wasting your time over this issue.  :-[

J
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Offline blackdalek

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Re: Looking for a specific bouncing ball demo.
« Reply #15 on: 23:09, 13 March 18 »
Okay... I am not sure where the weird errors came from because they are not in the file on my disk. I think something must have gone wrong during the transfer to my laptop and it got corrupted. Let me try save it again.
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Offline johnno56

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Re: Looking for a specific bouncing ball demo.
« Reply #16 on: 01:33, 14 March 18 »
Excellent. A "bug" free upload... Cool.

J
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Offline pelrun

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Re: Looking for a specific bouncing ball demo.
« Reply #17 on: 02:59, 14 March 18 »
It was published as a 10-liner in the May 1987 issue of Computing with the Amstrad, under the title 'Ball control'. Ian C. Sharpe is the author.


D'oh. I would have saved myself so much time if I'd thought to check the Aussie CWTA's, since there's so few of them. It showed up in the July 87 issue.


http://www.cpcwiki.eu/index.php/File:CWTA-AE-Jul87Page48.jpg

Offline Morri

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Re: Looking for a specific bouncing ball demo.
« Reply #18 on: 03:44, 14 March 18 »
Very simple use of the CRTC for hardware scrolling from BASIC by using R2 (HSync) & R7 (VSync).
I haven't experimenting with these 2 before. When I made my BASIC game CoolBox I used R12 & R13 but the results looked similar.

Can anyone explain the difference?
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Offline pelrun

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Re: Looking for a specific bouncing ball demo.
« Reply #19 on: 04:13, 14 March 18 »
R2/R3 change the position of the hsync/vsync pulses to the monitor, so the screen contents are static but where it's positioned on the monitor changes. R12/R13 changes how the CRTC reads out the display memory, so the screen position is static but the contents change.


The first demo in this thread uses R12/R13, because otherwise you'd also see the background grid bounce around the screen. It's limited to the regular screen area. The second one has a blank white background to hide the border movement, but it can bounce the ball off the very edges of the tube.

Offline blackdalek

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Re: Looking for a specific bouncing ball demo.
« Reply #20 on: 05:35, 14 March 18 »
Quote from: May 1987 issue of Computing with the Amstrad pg 48
"Type it in, and amaze you friends."

*your

Good to see there were people incapable of writing coherent grammar in Australian publishing even before the advent of autocorrect and touch screen phones.  :P ;)
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