Orbitals, a PSI Res program

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GCHarder
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Joined: Sat Dec 14, 2013 7:46 pm

Orbitals, a PSI Res program

Post by GCHarder »

This is a new listing from Popular Computing Weekly, 11/82. The program original printed hi-res output to the ZX Printer. I've converted it to display the output using the Pseudo Hi-Res video driver, therefore, it will run on a standard 16K ZX81. I've also included the original printer version as well.

Regards;

Greg
Screen shots
Screen shots
Orbitals.gif (21.46 KiB) Viewed 4700 times
Hardware test on a T/S 1000
Hardware test on a T/S 1000
TS1000 Test.jpg (52.67 KiB) Viewed 4700 times
Attachments
Orbitals.zip
Programs and info
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sirmorris
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Joined: Thu May 08, 2008 5:45 pm

Re: Orbitals, a PSI Res program

Post by sirmorris »

PSI-res. Haha I love it! :lol:
Fruitcake
Posts: 346
Joined: Wed Sep 01, 2010 10:53 pm

Re: Orbitals, a PSI Res program

Post by Fruitcake »

Hi Greg

The program looks great, especially with my hi-res font! :D

I tried the program using EightyOne and found that the picture was not being displayed properly:
OrbitalsEightyOne.gif
OrbitalsEightyOne.gif (14.47 KiB) Viewed 4648 times
I then tried it on a real ZX81 fitted with a Chroma interface and it did not like the picture either.

I think old TVs using an aerial connection were a lot more tolerant of slightly off timing.

Looking at the hi-res routine, it appears that the delay before rendering the top line of the display area is too short. A stable picture can be achieved by changing LD B,$12 to LD B,$14 at $5BD9, although then the picture will not be centred but shifted to the left. A better solution is to use timings matching those found in Forty Niner and Rocket Man as follows:

Code: Select all

@HRESGEN
       DI
       LD HL,$C061
       LD DE,$0021
       LD C,$FE
       LD B,$16
@SYNC3
Using these alternate timings, EightyOne shows the top line of the display offset a pixel or two but I believe this may just be an issue with the emulator as I do not see this offset using real hardware.


It is great to see these old type in programs in action. Have you submitted all the ones you have typed in for archiving at the The Type Fantastic website?
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GCHarder
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Re: Orbitals, a PSI Res program

Post by GCHarder »

I'm surprised that it didn't work in EO as the screen shots I posted are from EO. I can understand problems on real hardware, mainly due to the PAL/NTSC differences. I attempted to compensate for this by checking MARGINS before staring the hi-res display and adjusting the delay.

Thanks for making your font available for download, it's very nice. I have another font I extracted from a Hi-Res typewriter program, it's a bit larger using 7 line and 1 blank, but is a bit more ragged than yours.

Regards;

Greg
Fruitcake
Posts: 346
Joined: Wed Sep 01, 2010 10:53 pm

Re: Orbitals, a PSI Res program

Post by Fruitcake »

GCHarder wrote:Thanks for making your font available for download, it's very nice.
Thanks. The font dates from 1987 and comes from a hi-res utility I created to extend basic with new user friendly commands for manipulating a hi-res display (drawing, printing, circles, scrolling, etc). It is nice to see the font used to good effect all these years later. I hadn't actually realised it was my font to begin with, although I did think it looked very familiar. Then I saw my name and chuckled... :D

GCHarder wrote:I can understand problems on real hardware, mainly due to the PAL/NTSC differences.
The problem appears to be the timing of the left hand border of the first scan line of the main display area, and not due to the number of top/bottom border lines which does vary between 50Hz and 60Hz machines.

GCHarder wrote:I'm surprised that it didn't work in EO as the screen shots I posted are from EO
So far the only way I can get EightyOne to display the picture undistorted is by lowering the Horizontal Hold setting in the TV Emulation dialog (by default it is in the centre position). Could you check your TV Emulation settings. It would be very nice to be able to explain the difference.
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GCHarder
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Re: Orbitals, a PSI Res program

Post by GCHarder »

Here's a screenshot of my settings for EO and results for some other emulators. Forty Niner runs OK in EO and sx81, ZEsarUX still doesn't like the delay value, at least not on my set-up.

Regards;

Greg
Emulators.gif
Emulators.gif (79.65 KiB) Viewed 4573 times
karingal
Posts: 30
Joined: Mon Feb 04, 2013 2:30 pm

Re: Orbitals, a PSI Res program

Post by karingal »

This is the first program I've found in quite a while which doesn't run correctly on my emulator Spud81. I'll have to take a look at the code and see if I can get it to run. Perhaps I'll add horizontal and vertical setting to help.
karingal
Posts: 30
Joined: Mon Feb 04, 2013 2:30 pm

Re: Orbitals, a PSI Res program

Post by karingal »

Ok, so a quick bit of coding later and now Spud81 can run Orbitals correctly (assuming you tweak the horizontal hold setting!)

You can find Spud81 here - http://bit.ly/MYuLBX

Enjoy!!
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