Amiga questions you've always been too embarrassed to ask - Page 18

Marcuz · 07 May 2014, 01:48

hah! Good try

s2325 · 07 May 2014, 01:58

Maybe scene was turned and hand should be off-screen:

Mark Wright · 07 May 2014, 02:01

Here's an obscure Amiga "feature" that I've often wondered about (having never read an explanation) that was hugely beneficial to me, but little-known or acknowledged.

I can clearly recall the excitement I felt upon finally coaxing near-CD quality, stereo, streaming audio from a stock A1200 (with HD) in 1994 - but it was ONLY possible when running a VGA-ish screenmode. Quite how I discovered this best-kept secret is now lost to time, though I'll never forget the trauma caused by trying to "tune-in" various (squealing) SVGA monitors using a hardware-bashing utility that regularly threatened to take an eye out ;-).

The result was worth it though. Remember, I'm talking about NEAR CD-QUALITY, STEREO, STREAMING AUDIO from a stock A1200. In 1994. The quality was incredible. I think it had something to do with AHI drivers. Or a program called Play16. Or something. I never understood the alchemy at the time; hazy memory isn't helping either! How did this work - and why?

Incidentally, the reason this "feature" was beneficial to me back in 1994... I was working as an engineer at a radio station just as PC audio playout was being introduced. As a die-hard Amigan, faced with the prospect of working with clunky, unreliable, expensive Windows PCs, I devised an intuitive, effective and affordable "creative solution" based around this Amiga phenomenon. You can imagine the sense of achievement I felt once I'd installed a cluster of A1200s to handle things like advertisements and jingles. It worked a treat and saved the station thousands of pounds, but as standardisation took hold, the set-up didn't last long. I wish I could remember how I did it!

Cobe · 07 May 2014, 03:02

How did Commodore imagine to be proper way to change a game or turn off CD32?

ajk · 07 May 2014, 08:35

@Mark Wright

That's the 14 bit Paula mode you are thinking of, quite a widespread trick actually. It is achieved by combining the four channels into two channels by clever manipulation of the volume levels. You remembered all the necessary details, just see Play16 and AHI

Hewitson · 07 May 2014, 10:37

Quote:

Originally Posted by ajk

@Mark Wright

That's the 14 bit Paula mode you are thinking of, quite a widespread trick actually. It is achieved by combining the four channels into two channels by clever manipulation of the volume levels. You remembered all the necessary details, just see Play16 and AHI

He's actually talking about the 56khz samplerate, although he may well have used it in conjunction with the 14 bit mode.

Toni Wilen · 07 May 2014, 11:25

56KHz sample rate works only in VGA modes because audio channel DMA slots are hardwired to start of each scan line. 1 PAL/NTSC scan line is about 2x longer than VGA compatible scanline = 2x more audio DMA slots available = 2x larger sample rate is possible.

Mark Wright · 11 May 2014, 01:32

Fascinating. Although I only vaguely understand the answer ;-)

I've since remembered my smug grin of satisfaction at being able to play PC multichannel XM modules on my old A1200 (with 030/2MB accellerator jobbie) back in around 1995, presumably using the same trick. I also had some sort of CLI-driven general MIDI player that rendered GM files using the same sort of wavetable that was found in those old Creative AWE cards. The quality was very un-Amiga like - HD resolution, making regular Paula ouput sound like bitty/scratchy Atari ST sample playback.

Actually, thinking about it, I had an 030/2MB accellerator jobbie for my A1200 (I'm sure I was able to play the odd MP2 I could afford to download on dial-up too!) but given the right conditions, could even a 1985 Paula in an A1000 be made to output at 56kHz from a regular 8SVX/PCM file? What's the chain of dependencies that makes it possible? Only with AGA since that's when VGA screenmodes were possible? Only with 68020+ (and/or with AGA)? Was it a dormant "hidden" feature all along, just waiting to be unlocked?

I was surprised/disappointed that improved audio quality wasn't announced as part of the AGA machines at the time. Maybe CBM missed (yet another) trick that could have easily been realised...

Hewitson · 15 May 2014, 07:00

A 1985 A1000 would be capable of 56khz playback if the chipset was upgraded to ECS. The VGA screenmode is not exclusive to AGA.

jPV · 15 May 2014, 07:42

Quote:

Originally Posted by Mark Wright

Here's an obscure Amiga "feature" that I've often wondered about (having never read an explanation) that was hugely beneficial to me, but little-known or acknowledged.

It was widely used with graphics cards. Both CGX and P96 RTG systems have option to put native (and mostly unused) output to 56kHz. Then you could have better sample rate no matter which display modes you used on RTG.

s2325 · 28 May 2014, 07:11

Are enemies from Ninja Warriors possessed? Is it to hide game brutality?

kkgarbod · 28 May 2014, 09:20

Me've been wondering about this (since me never playred with it, and ...) How do one install PFS 3 (since the install instructions say CD and the Free release comes in a zip)

Hewitson · 28 May 2014, 10:04

Quote:

Originally Posted by kkgarbod

Me've been wondering about this (since me never playred with it, and ...) How do one install PFS 3 (since the install instructions say CD and the Free release comes in a zip)

Just unzip it to a directory and treat that directory as if it was the CD. It's not going to perform any sort of cd-check.

mc6809e · 28 May 2014, 19:10

Quote:

Originally Posted by Mark Wright

but given the right conditions, could even a 1985 Paula in an A1000 be made to output at 56kHz from a regular 8SVX/PCM file? What's the chain of dependencies that makes it possible?

With minimal CPU intervention, the limit is around 28KHz (DMA mode), but if the CPU or the copper is used for playing samples, 56KHz is playable on a regular A1000.

ajack · 04 June 2014, 05:43

Can I do an in-place upgrade of my A500's 68000 7MHz processor with a 10MHz 68010? I was under the impression it's be 10% faster at the same clock speed and I will be using it in an under-clocked manner at 7MHz instead of 10MHz. So, can I just swap 'em? Anything to note? Problems? Compatibility issues?

demolition · 04 June 2014, 05:55

Quote:

Originally Posted by ajack

Can I do an in-place upgrade of my A500's 68000 7MHz processor with a 10MHz 68010? I was under the impression it's be 10% at the same clock speed and I will be using it in an under-clocked manner at 7MHz instead of 10MHz. So, can I just swap 'em? Anything to note? Problems? Compatibility issues?

Most things will work just fine, and it is a straight pin compatible replacement. I have such an 010 10 MHz in my A500+ and one of my 600s (clocked to the standard ~7MHz). There is a slight speed boost to most things, the WHDLoad quit key will work, but a few original floppy games will not like the 010.

ajack · 04 June 2014, 06:03

Quote:

Originally Posted by demolition

Most things will work just fine, and it is a straight pin compatible replacement. I have such an 010 10 MHz in my A500+ and one of my 600s (clocked to the standard ~7MHz). There is a slight speed boost to most things, the WHDLoad quit key will work, but a few original floppy games will not like the 010.

Thanks for the quick reply, much appreciated...

Hewitson · 04 June 2014, 13:55

I upgraded my A2000 with an 010, solely to enable quitting from WHDLoad. Haven't noticed any speed increase, and haven't encountered any incompatible games (although I'm sure they do exist).

If you're not using WHDLoad on the machine, my advice would be don't bother.

Codetapper · 04 June 2014, 14:05

Quote:

Originally Posted by Hewitson

I upgraded my A2000 with an 010, solely to enable quitting from WHDLoad. Haven't noticed any speed increase, and haven't encountered any incompatible games (although I'm sure they do exist).

If you're not using WHDLoad on the machine, my advice would be don't bother.

Most well written slaves should quit with WHDLoad anyway even on a 68000. If they don't, the author didn't bother to patch the keyboard routine properly to detect the quit key.

Hewitson · 04 June 2014, 15:38

Quote:

Originally Posted by Codetapper

Most well written slaves should quit with WHDLoad anyway even on a 68000. If they don't, the author didn't bother to patch the keyboard routine properly to detect the quit key.

I'm going back a few years but many of them did not allow me to quit without at least an 010. I have no idea whether that is still the case, I apologise if it isn't.

04 June 2014, 05:43	#355
ajack Registered User Join Date: May 2014 Location: Malaysia Posts: 115	Can I do an in-place upgrade of my A500's 68000 7MHz processor with a 10MHz 68010? I was under the impression it's be 10% faster at the same clock speed and I will be using it in an under-clocked manner at 7MHz instead of 10MHz. So, can I just swap 'em? Anything to note? Problems? Compatibility issues? Last edited by ajack; 04 June 2014 at 06:04.

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07 May 2014, 01:48	#341
Marcuz Registered User Join Date: Jun 2002 Location: . Age: 48 Posts: 5,562	hah! Good try

07 May 2014, 01:58	#342
s2325 Zone Friend Join Date: Jun 2006 Location: Gargore Age: 43 Posts: 17,789	Maybe scene was turned and hand should be off-screen:

07 May 2014, 02:01	#343
Mark Wright Junior Member Join Date: Feb 2003 Location: Hove, actually Posts: 218	Here's an obscure Amiga "feature" that I've often wondered about (having never read an explanation) that was hugely beneficial to me, but little-known or acknowledged. I can clearly recall the excitement I felt upon finally coaxing near-CD quality, stereo, streaming audio from a stock A1200 (with HD) in 1994 - but it was ONLY possible when running a VGA-ish screenmode. Quite how I discovered this best-kept secret is now lost to time, though I'll never forget the trauma caused by trying to "tune-in" various (squealing) SVGA monitors using a hardware-bashing utility that regularly threatened to take an eye out ;-). The result was worth it though. Remember, I'm talking about NEAR CD-QUALITY, STEREO, STREAMING AUDIO from a stock A1200. In 1994. The quality was incredible. I think it had something to do with AHI drivers. Or a program called Play16. Or something. I never understood the alchemy at the time; hazy memory isn't helping either! How did this work - and why? Incidentally, the reason this "feature" was beneficial to me back in 1994... I was working as an engineer at a radio station just as PC audio playout was being introduced. As a die-hard Amigan, faced with the prospect of working with clunky, unreliable, expensive Windows PCs, I devised an intuitive, effective and affordable "creative solution" based around this Amiga phenomenon. You can imagine the sense of achievement I felt once I'd installed a cluster of A1200s to handle things like advertisements and jingles. It worked a treat and saved the station thousands of pounds, but as standardisation took hold, the set-up didn't last long. I wish I could remember how I did it!

07 May 2014, 03:02	#344
Cobe Registered User Join Date: Jan 2014 Location: Belgrade / Serbia Age: 41 Posts: 1,004	How did Commodore imagine to be proper way to change a game or turn off CD32?

07 May 2014, 08:35	#345
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	@Mark Wright That's the 14 bit Paula mode you are thinking of, quite a widespread trick actually. It is achieved by combining the four channels into two channels by clever manipulation of the volume levels. You remembered all the necessary details, just see Play16 and AHI

07 May 2014, 11:25	#347
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,516	56KHz sample rate works only in VGA modes because audio channel DMA slots are hardwired to start of each scan line. 1 PAL/NTSC scan line is about 2x longer than VGA compatible scanline = 2x more audio DMA slots available = 2x larger sample rate is possible.

11 May 2014, 01:32	#348
Mark Wright Junior Member Join Date: Feb 2003 Location: Hove, actually Posts: 218	Fascinating. Although I only vaguely understand the answer ;-) I've since remembered my smug grin of satisfaction at being able to play PC multichannel XM modules on my old A1200 (with 030/2MB accellerator jobbie) back in around 1995, presumably using the same trick. I also had some sort of CLI-driven general MIDI player that rendered GM files using the same sort of wavetable that was found in those old Creative AWE cards. The quality was very un-Amiga like - HD resolution, making regular Paula ouput sound like bitty/scratchy Atari ST sample playback. Actually, thinking about it, I had an 030/2MB accellerator jobbie for my A1200 (I'm sure I was able to play the odd MP2 I could afford to download on dial-up too!) but given the right conditions, could even a 1985 Paula in an A1000 be made to output at 56kHz from a regular 8SVX/PCM file? What's the chain of dependencies that makes it possible? Only with AGA since that's when VGA screenmodes were possible? Only with 68020+ (and/or with AGA)? Was it a dormant "hidden" feature all along, just waiting to be unlocked? I was surprised/disappointed that improved audio quality wasn't announced as part of the AGA machines at the time. Maybe CBM missed (yet another) trick that could have easily been realised...

15 May 2014, 07:00	#349
Hewitson Registered User Join Date: Feb 2007 Location: Melbourne, Australia Age: 41 Posts: 3,773	A 1985 A1000 would be capable of 56khz playback if the chipset was upgraded to ECS. The VGA screenmode is not exclusive to AGA.

28 May 2014, 07:11	#351
s2325 Zone Friend Join Date: Jun 2006 Location: Gargore Age: 43 Posts: 17,789	Are enemies from Ninja Warriors possessed? Is it to hide game brutality?

28 May 2014, 09:20	#352
kkgarbod The Human/Gray Hybrid Join Date: Dec 2009 Location: The Elizabeth Arkham Asylum for the Criminally Insane Posts: 372	Me've been wondering about this (since me never playred with it, and ...) How do one install PFS 3 (since the install instructions say CD and the Free release comes in a zip)

04 June 2014, 13:55	#358
Hewitson Registered User Join Date: Feb 2007 Location: Melbourne, Australia Age: 41 Posts: 3,773	I upgraded my A2000 with an 010, solely to enable quitting from WHDLoad. Haven't noticed any speed increase, and haven't encountered any incompatible games (although I'm sure they do exist). If you're not using WHDLoad on the machine, my advice would be don't bother.

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