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CGC entry - one for the hardware types

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  CGC entry - one for the hardware types R-Tape <stonechatproductions@yahoo.co.uk> - 2013-06-30 01:15 -0700
    Re: CGC entry - one for the hardware types "Paul E Collins" <equi@cl4.invalid> - 2013-06-30 17:15 +0100
      Re: CGC entry - one for the hardware types Hanno Foest <hurga-news2@tigress.com> - 2013-07-01 00:00 +0200
        Re: CGC entry - one for the hardware types Guesser <alistair@alistairsserver.no-ip.org> - 2013-07-01 21:34 +0100
          Re: CGC entry - one for the hardware types spike1@freenet.co.uk - 2013-07-02 18:34 +0100
          Re: CGC entry - one for the hardware types "Chris Young" <chris.usenet@mail-filter.com> - 2013-07-02 19:18 +0100
            Re: CGC entry - one for the hardware types Guesser <alistair@alistairsserver.no-ip.org> - 2013-07-02 19:37 +0100
              Re: CGC entry - one for the hardware types SamTek <rogerjowett@gmail.com> - 2013-07-03 03:06 -0700
                Re: CGC entry - one for the hardware types Sophie Braine <choralmissy@gmail.com> - 2013-07-13 01:15 -0700
                  Re: CGC entry - one for the hardware types korax1214@gmail.com - 2013-07-14 07:16 -0700
      Re: CGC entry - one for the hardware types Andrew Owen <aowen10@mail.bbk.ac.uk> - 2013-07-02 18:38 +0100
        Re: CGC entry - one for the hardware types "Chris Young" <chris.usenet@mail-filter.com> - 2013-07-02 19:19 +0100
        Re: CGC entry - one for the hardware types Guesser <alistair@alistairsserver.no-ip.org> - 2013-07-02 19:34 +0100
    Re: CGC entry - one for the hardware types ec429 <ec429@cantab.ac.uk> - 2013-08-28 00:57 +0100
      Re: CGC entry - one for the hardware types Guesser <alistair@alistairsserver.no-ip.org> - 2013-08-28 02:55 +0100

#2298 — CGC entry - one for the hardware types

New entry to the CGC: Chromatrons Attack by Guesser, music by Gasman.

Due to his advanced 'PAL-distorotron engine' you cannot play/view this game on an emulator, only on real 128k speccy with telly.

www.csscgc2013.blogspot.com

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#2299

On Sun, 30 Jun 2013 09:15:53 +0100, R-Tape  
<stonechatproductions@yahoo.co.uk> wrote:

> New entry to the CGC: Chromatrons Attack by Guesser, music by Gasman.  
> Due to his advanced 'PAL-distorotron engine' you cannot play/view this  
> game on an emulator, only on real 128k speccy with telly.

That is such a brilliant idea.

We now require a new feature in emulators (which doesn't happen often).

Eq.

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#2300

Am 30.06.2013 18:15, schrieb Paul E Collins:

>> New entry to the CGC: Chromatrons Attack by Guesser, music by Gasman.
>> Due to his advanced 'PAL-distorotron engine' you cannot play/view this
>> game on an emulator, only on real 128k speccy with telly.
>
> That is such a brilliant idea.
>
> We now require a new feature in emulators (which doesn't happen often).

That would defeat the idea...

Anyway, how is it done?

Hanno

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#2301

On 30/06/2013 23:00, Hanno Foest wrote:
> Anyway, how is it done?
>
> Hanno

Oops, I missed this.

The short and techy answer is that the TV is unable to completely 
separate the high frequency transitions in the luminance signal from the 
modulated chrominance, so some of the black and white signal leaks into 
the colour.

By generating a specific pattern on screen that high frequency cross 
colour interference can be manipulated to make the TV generate stable 
blocks of colour.

The effect is being caused by the limitations of the analogue video 
circuitry and the way a PAL video signal works. Emulators of course 
represent an ideal video signal with unlimited bandwidth etc and make no 
attempt to accurately model a PAL signal :D

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#2303

And verily, didst Guesser <alistair@alistairsserver.no-ip.org> hastily babble thusly:
> On 30/06/2013 23:00, Hanno Foest wrote:
>> Anyway, how is it done?
>>
>> Hanno
> 
> Oops, I missed this.
> 
> The short and techy answer is that the TV is unable to completely 
> separate the high frequency transitions in the luminance signal from the 
> modulated chrominance, so some of the black and white signal leaks into 
> the colour.
> 
> By generating a specific pattern on screen that high frequency cross 
> colour interference can be manipulated to make the TV generate stable 
> blocks of colour.
> 
> The effect is being caused by the limitations of the analogue video 
> circuitry and the way a PAL video signal works. Emulators of course 
> represent an ideal video signal with unlimited bandwidth etc and make no 
> attempt to accurately model a PAL signal :D

How about bunging up a youtube video showing the effect?... 

(won't work on my 128 cos the colour conked out yonks ago)
-- 
|   spike1@freenet.co.uk   | "I'm alive!!! I can touch! I can taste!         |
|   Andrew Halliwell BSc   |  I can SMELL!!!  KRYTEN!!! Unpack Rachel and    |
|            in            |  get out the puncture repair kit!"              |
|     Computer Science     |     Arnold Judas Rimmer- Red Dwarf              |

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#2304

On Mon, 01 Jul 2013 21:34:28 +0100 da kidz on comp.sys.sinclair were rappin'
to MC Guesser:

> The effect is being caused by the limitations of the analogue video 
> circuitry and the way a PAL video signal works. Emulators of course 
> represent an ideal video signal with unlimited bandwidth etc and make no 
> attempt to accurately model a PAL signal :D

Don't some emulators have "PAL emulation"?

Mind you I find those options don't look anything like PAL and it's
better not to bother with them.  Answered my own question there.

Chris


-- 
+-------------------------------------------+
| Unsatisfactory Software - "because it is" |
|  http://www.unsatisfactorysoftware.co.uk  |
| Your Sinclair: A Celebration              |
+- http://www.yoursinclair.co.uk -----------+

DISCLAIMER: I may be making all this stuff up again.

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#2307

On 02/07/2013 19:18, Chris Young wrote:
> Don't some emulators have "PAL emulation"?
>
> Mind you I find those options don't look anything like PAL and it's
> better not to bother with them.  Answered my own question there.
>

Exactly, I have no idea what "PAL emulation" in emulators is supposed to 
do and no two emulators seem to mean the same thing by it.

Then there are emulators that do TV screen modes. Eightyone for example 
comes pretty close but still only fakes an effect which looks sort of close.

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#2308

eighty one doesn't really look exactly like uhf crt tv output - it is a bit more fuzzy and blurry but still it has very little to do with crosstalk synchronization and there is still no sign of phosphoric delay

does the ula+ spectra zx prism think of adding a fully compatible recreation of this ultra blurry original - even if it has to be hardware selected?
can anyone figure out a way of retaining some compatibility but reducing the amount of video ram contention  i was trying to find out if a 32 byte buffer could be used to store a row of attributes so that they only need read once instead of being reread 8 times - would that have any effect on the contention? - clearly it would cock up rainbow colour effects but then there isn't much more than a handful of such programs- maybe if it was possible to select the attribute buffer mode with a small amount of code and deselect it?

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#2310

On Wednesday, 3 July 2013 20:06:29 UTC+10, SamTek  wrote:

> does the ula+ spectra zx prism think of adding a fully compatible recreation of this ultra blurry original - even if it has to be hardware selected?

ULA+, Spectra and ZX Prism are three different things.

I cannot speak for ULA+ (though in its form as a plug-in replacement for the Spectrum ULA it might) or Spectra, but ZX Prism will not be doing any sort of TV emulation or pixel blurring, no. 

> can anyone figure out a way of retaining some compatibility but reducing the amount of video ram contention

ZX Prism does this - the video RAM is internal to the FPGA and dual ported - the video circuitry uses one port and the CPU uses the other. Memory contention is therefore not required at all (though it can be emulated)

Some Russian Spectrum clones also have reduced or no memory contention I believe.

>>i was trying to find out if a 32 byte buffer could be used to store a row of attributes so that they only need read once instead of being reread 8 times - would that have any effect on the contention?

That would be feasible to do in a decent sized CPLD or an FPGA, but as it doesn't add TOO much benefit, I don't know if you'd convince anyone making ULA replacements or emulators to do it. You'd be better off dual porting the RAM (or timeslicing it) and removing contention altogeter and/or increasing the CPU speed.

Jeff

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#2311

On Saturday, 13 July 2013 09:15:35 UTC+1, Jeff Braine  wrote:
> On Wednesday, 3 July 2013 20:06:29 UTC+10, SamTek  wrote:
> > does the ula+ spectra zx prism think of adding a fully compatible recreation of this ultra blurry original - even if it has to be hardware selected?
> ULA+, Spectra and ZX Prism are three different things.

You're expecting SpamTrek to make sense?!?! I added him to my mental[1] killfile long ago...

[1] Well, he does indeed appear to be mental...

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#2302

On 30/06/2013 17:15, Paul E Collins wrote:
> We now require a new feature in emulators (which doesn't happen often).

Not necessarily. It's just possible that it might work under Fuse 
running on the Raspberry Pi hooked up to a 50Hz PAL display via the 
composite out. Haven't had a chance to try it yet.

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#2305

On Tue, 02 Jul 2013 18:38:55 +0100 da kidz on comp.sys.sinclair were rappin'
to MC Andrew Owen:

> On 30/06/2013 17:15, Paul E Collins wrote:
> > We now require a new feature in emulators (which doesn't happen often).
> 
> Not necessarily. It's just possible that it might work under Fuse 
> running on the Raspberry Pi hooked up to a 50Hz PAL display via the 
> composite out. Haven't had a chance to try it yet.

I suspect if you're full screen with "perfect" pixel output, it
_should_ have the correct effect.  I suspect the Pi's composite output
is a heck of a lot better than the Speccy's though.

Chris


-- 
+-------------------------------------------+
| Unsatisfactory Software - "because it is" |
|  http://www.unsatisfactorysoftware.co.uk  |
| Your Sinclair: A Celebration              |
+- http://www.yoursinclair.co.uk -----------+

DISCLAIMER: I may be making all this stuff up again.

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#2306

On 02/07/2013 18:38, Andrew Owen wrote:
> On 30/06/2013 17:15, Paul E Collins wrote:
>> We now require a new feature in emulators (which doesn't happen often).
>
> Not necessarily. It's just possible that it might work under Fuse
> running on the Raspberry Pi hooked up to a 50Hz PAL display via the
> composite out. Haven't had a chance to try it yet.

It won't because the pi has good video generation circuits that output 
much close to a perfect signal.

Part of the reason the speccy has such a large amount of this cross 
colour distortion is the way the circuit is constructed (i.e. cheaply).

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#2395

On 30/06/13 09:15, R-Tape wrote:
> Due to his advanced 'PAL-distorotron engine' you cannot play/view this game on an emulator, only on real 128k speccy with telly.
This is no longer true.
As of version 0.7.0, Spiffy can play this game.  Evidence in a screenshot:
http://jttlov.no-ip.org/img/spiffy_chroma.png

(Currently only available for Linux, but I'll have another crack at 
Windows cross-builds soon.)

Actually, I had PAL distort-O-tron working months ago - what held it up 
was getting round to adding 128k support.

-Edward (aka AYChip, aka Guesser's brother)
-- 
'sane', adj.: see 'unimaginative'
   on the web - http://jttlov.no-ip.org

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#2396

On 28/08/2013 00:57, ec429 wrote:
> Actually, I had PAL distort-O-tron working months ago - what held it up
> was getting round to adding 128k support.

it's getting /close/ colours are still way off though.

here's a static test scr http://alistairtesting.no-ip.org/test.scr

If you can make a screenshot of a single frame it might aid diagnosis :)

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