Crappy comparison of Amiga 1200 vs Atari Falcon

[matthey]

That depends on what you mean by general purpose. A lot of home users use their computers for multimedia or games, and some have sound cards in their computers for this purpose, and these will usually contain a DSP. For example, if you had a Sound blaster from the late 90's or later you had a DSP in your computer, and some modern graphics cards have them. The Playstation 4 has one, although it's a quite a stretch to call that a general purpose computer.

A DSP on sound cards was more common before modern CPUs which have more processing power and DSP like functionality, especially SIMDs. There still is the possibility of off-loading the CPU but most audio processing only uses a few percent of a modern medium to high performance CPU's processing power. An SIMD often has more performance than a DSP albeit at a higher cost. Perhaps the PS4 is trying to save electricity as consoles need to be more power efficient and a DSP wins over an SIMD here. However, the PS4 likely has multiple SIMD units which could do more complex audio processing faster and the overall hardware cost could be reduced by a small amount. It would be interesting to hear why the PS4 engineers included the DSP. I wouldn't be surprised if it was because they used an existing off the shelf mature audio design which included a DSP. There are probably DSPs on motherboard integrated PC audio hardware for this reason. Newly designed general purpose computers are unlikely to get an off the shelf DSP like the Falcon or A3000+. Many people seem to still want a DSP when they would be much better off with a faster CPU and/or SIMD. That was my point even if my use of "never" was perhaps too harsh.

Of course, the very name "DSP" implies a non-general purpose, but practically speaking, sound and graphics processing should be covered.

A DSP can be used for some graphics processing and they are efficient but most are not particularly flexible or fast. An SIMD is a better choice for graphics as it is more powerful, more flexible and generally easier to program. We have modern graphics processors and hardware which are more powerful yet. Audio processing is mostly simpler, more repetitive and less processor intensive which is perfect for a DSP. Still, there are many reasons why a DSP processor chip would not be used in a completely new design.

[kovacm]

interesting topics: SIMD and DSP in modern days...

I read that AmigaOne X1000 have XMOS xCORE chip (and XMOS have some roots in Transputer era

is there any practical use of this chip or any demo that would show possibilities of xCORE?


btw IBM Cell looks like DSP: SPE's has it's own memory, no cache...

[QuikSanz]

There have been many interesting ideas but from what I understand that all tools have not been ported yet.

Some ideas: Telescope controller/viewer, Home automation controller and others. There are some threads in the forums with many of them.

[matthey]

interesting topics: SIMD and DSP in modern days...

I read that AmigaOne X1000 have XMOS xCORE chip (and XMOS have some roots in Transputer era

is there any practical use of this chip or any demo that would show possibilities of xCORE?

Define practical. More processing power using extra processors can always be used but is it worthwhile? Weak processors with strong processors are generally not worth messing with for most programmers. Take the classic Amiga blitter for example, it is mostly unused on accelerated Amigas even though a few programs have used the blitter and fast CPU in parallel. Processors which are distant from the CPU like the Amiga blitter, a DSP, an xCORE or a GPU unit take a long time to setup as compared to a CPU co-processor like an SIMD, MMU or FPU. This is one of the reasons why DSP like instructions (ARM) and SIMDs are added to modern CPUs. OS software libraries can make it easier to use CPU external processors like the graphics.library does for the blitter but the use is generally narrow. Many weak processors can be used in parallel making them worthwhile. Some weak processors can offload I/O processing and have external hardware connections. The xCORE processors looks like they fit in this category but were not added for a particular purpose. I have only done basic reading about the xCore but it looks to me like a descent sized user usable FPGA would have been a better choice with more flexibility and processing power. The SAM Lattice FPGA is the right idea but it is too small for all but the simplest uses (GeekPort for embedded uses). Add a more popular FPGA big enough to handle retro chipsets and CPUs with open documentation and development tools and then you would have something retro and embedded markets would be attracted to.

btw IBM Cell looks like DSP: SPE's has it's own memory, no cache...

There are some similarities including the difficulty of programming which is what has killed Cell. The theoretical peak processing power of Cell is very good if the code is perfect. The PPC processor in Cell also looks good on paper but it is bubblicious. Cell SPEs may use less electricity than SMP but the difficulty of coding killed it. Ease of programming and compiler construction keeps getting ignored for theoretical performance and processor simplification (compilers often can't handle the complexity as well as the hardware processor).

[Bif]

A DSP on sound cards was more common before modern CPUs which have more processing power and DSP like functionality, especially SIMDs. There still is the possibility of off-loading the CPU but most audio processing only uses a few percent of a modern medium to high performance CPU's processing power. An SIMD often has more performance than a DSP albeit at a higher cost. Perhaps the PS4 is trying to save electricity as consoles need to be more power efficient and a DSP wins over an SIMD here. However, the PS4 likely has multiple SIMD units which could do more complex audio processing faster and the overall hardware cost could be reduced by a small amount. It would be interesting to hear why the PS4 engineers included the DSP.

As a guy who has done nothing but audio coding my whole career I can agree that being able to move everything off of DSPs and on to the high performance main CPUs that came along is a great thing, at least for us writing audio code. Auxiliary processors can box you in and are generally just a PITA to deal with. They are also often closed off, only presenting some high level API to interact with.

I might be cautious in saying the PS4 has a "DSP". It is not targeted for general purpose audio processing, the main CPU is what does all that. The "DSP" mostly deals with encoding and decoding. Is that a DSP, or is it just another auxiliary processor that is cost effective at that task? There might be some other DSPs on the machine I am unaware of, there are a number of them that perform various tasks, but none that synthesize the game audio like some might think.

I'm also not sure if you'd say the Cell is super DSP-like. Its instruction set is quite general purpose, but designed for modern SIMD computing (lean and mean). Its memory architecture is not at all general purpose, and more DSP like, I guess. It's interesting, to say the least.

Reading this thread I now kind of wish I had a Falcon way back when it came out. It would have been a great machine to code the audio software I wanted to develop with its 16-bit capability, and back then the DSP was needed with the main CPU being too weak for anything interesting with audio. I guess I had moved on to PCs and sound cards by that time though.

Relating this back to the Amiga I wouldn't actually mind if someone came out with a new sound card for it that had a bitchin' DSP-like processor on it. Given the Amiga tops out at 68060 you kind of need it if you want to do lots of crazy stuff. Either that or some of these new accelerators that could move us way past 060 performance, that would be even better.

[psxphill]

Problem is that AmigaOS needs atleast the CIAs to work at all and either the rest of the chipset or massive patching (CGX/P96) to be really usefull.

Yes, essentially you need to write a new bootstrap, timer device, new trackdisk device, a cgx/p96 driver, AHI device and an scsi/ide device.

Quite a difference to running MacOS or TOS on an Amiga where all you needed was the ROM-images and a few mild patches.

It's unlikely to be much different to be honest. At least the amount of Mac patches wasn't trivial.

I might be cautious in saying the PS4 has a "DSP". It is not targeted for general purpose audio processing, the main CPU is what does all that. The "DSP" mostly deals with encoding and decoding. Is that a DSP, or is it just another auxiliary processor that is cost effective at that task?

It's mostly a marketing term. A DSP is an embedded cpu that has certain attributes. It can be manufactured to purely run unchangeable software from an internal ROM to perform a single function and still be a DSP. Old modems for instance used DSP's, flash came along eventually and some of them could be upgraded. The first DSP was the TMS5100 used in the speak and spell.

http://ethw.org/Milestones:Speak_%26_Spell,_the_First_Use_of_a_Digital_Signal_Processing_IC_for_Speech_Generation,_1978

Within recent years a tms5100 chip has been decapped and the mask rom dumped.

[matthey]

As a guy who has done nothing but audio coding my whole career I can agree that being able to move everything off of DSPs and on to the high performance main CPUs that came along is a great thing, at least for us writing audio code. Auxiliary processors can box you in and are generally just a PITA to deal with. They are also often closed off, only presenting some high level API to interact with.

It's nice to have someone from the industry give their insights.

I might be cautious in saying the PS4 has a "DSP". It is not targeted for general purpose audio processing, the main CPU is what does all that. The "DSP" mostly deals with encoding and decoding. Is that a DSP, or is it just another auxiliary processor that is cost effective at that task? There might be some other DSPs on the machine I am unaware of, there are a number of them that perform various tasks, but none that synthesize the game audio like some might think.

Yes, the lines are blurred between what is and isn't a DSP processor. FPGAs can be programmed to handle repetitive little data processing tasks or an FPGA DSP processor can be used but stripped of any functionality it doesn't need (before the development FPGA become a hard chip). Specialized and customized processors are very efficient and much easier to create today.

I'm also not sure if you'd say the Cell is super DSP-like. Its instruction set is quite general purpose, but designed for modern SIMD computing (lean and mean). Its memory architecture is not at all general purpose, and more DSP like, I guess. It's interesting, to say the least.

The SPEs are probably more like modern GPU shading units (which have also become more general purpose) while they are all data stream processors. I wonder if the Cell SPEs could have been supported with OpenCL and an OS library for OpenCL. Sometimes how the hardware is offered and supported makes all the difference. An FPGA can also be configured as parallel OpenCL units and an opencl.library could support available GPU shading units, FPGA parallel processing units and/or the main CPU/FPU/SIMD for parallel tasks.

Relating this back to the Amiga I wouldn't actually mind if someone came out with a new sound card for it that had a bitchin' DSP-like processor on it. Given the Amiga tops out at 68060 you kind of need it if you want to do lots of crazy stuff. Either that or some of these new accelerators that could move us way past 060 performance, that would be even better.

A DSP on a sound card still makes some sense as the CPU can vary and is far away across a shared bus introducing the possibilities of unacceptable latencies. Fast modern buses and large buffers probably help but most customers aren't going to tolerate a sound card which glitches and pauses.

Too bad A-Eon didn't realize there was an audio and DSP expert on their forum. The Prisma Megamix could have become a real sound card .

Gunnar was playing with an SIMD unit for the Apollo 68k FPGA core. It is Altivec like but with some simple CISC 68k style addressing modes added and some memory alignment restrictions dropped which would make it much easier to use while remaining mostly compatible with Altivec at the instruction level. Integer support is fairly cheap to implement in an SIMD but floating point is expensive. My advise was to support the 68k FPU (like 68060 FPU but with a few enhancements) for compatibility and forget about trying to add an SIMD unit until there is room (and probably single precision FP support as well). As I have thought about it more recently though, I would like to explore adding 2x 16 bit operations in a 32 bit register to the 68k integer units. Encoding space is limited so I would leave out 4x 8 bit operations. RGBA type byte color component operations could still be done in 1 cycle with superscalar instruction interleaving and there was already support for a PERM instruction which could load bytes into registers in any byte order wanted. It would have been helpful to have someone with industry experience in audio processing as part of our group. Maybe Gunnar would have even listened to you but probably not. He creates these nice "teams" which work to pull in ideas and build a consensus and then he ignores the consensus and does everything his own way with little explanation. The technology is real though and 68060 performance is being surpassed in an affordable FPGA. Perhaps up to double the performance of the 68060 is possible in the next few years in an affordable FPGA but "way past 060 performance" would probably require an ASIC. An ASIC would probably be required to fit a good SIMD unit with single precision FP also.

[Rob]

interesting topics: SIMD and DSP in modern days...

I read that AmigaOne X1000 have XMOS xCORE chip (and XMOS have some roots in Transputer era

is there any practical use of this chip or any demo that would show possibilities of xCORE?


btw IBM Cell looks like DSP: SPE's has it's own memory, no cache...

Although I did see a cool scrolling Super Mario demo the xCORE is aimed more at I/O operations.

One of the best projects I've seen, and experienced, was Randon International's Rain Room.  It's used sensors and valves controlled by an xCORE processor to create a corridor of torrential rain that parted around you as you walked through it.

With the X1000 and X5000, it is only really likely to come of use to people with the skills and need/desire to create something with it, and whether or not that would result in something that would be of interest to the average user is another matter.

I can imagine that if the guys who used Amigas at NASA were still there it might be something they'd be interested in.

The main thing going against it is that the small userbase of A-EON hardware limits the chances of someone creating something really interesting with it.  The other problem is that so far it hasn't been demonstrated that an xCORE chip connected to the CPU local bus has any advantage over one that isn't.

[Pyromania]

I played with an Atari ST the other day. It hasn't aged well, it's pretty crappy!

[Iggy]

I played with an Atari ST the other day. It hasn't aged well, it's pretty crappy!

True, but then most of us wear rose colored glasses when waxing poetic about the Amiga.

Fact is, at least with games, it doesn't seem to perform much better than a Sega Genesis.

[matthey]

I played with an Atari ST the other day. It hasn't aged well, it's pretty crappy!

I thought you might be trolling but then noticed you are a moderator. An original unexpanded 500, 1000 or 2000 isn't much better.

Fact is, at least with games, it doesn't seem to perform much better than a Sega Genesis.

The Sega Genesis came out some 3 years later than the Atari ST with more powerful hardware (plus its a computer vs console). That would be almost as bad as comparing the Genesis to the Atari Falcon which came out several years after the Genesis. The Amiga 1200 vs Atari Falcon and Amiga 1000 vs Atari ST are much fairer comparisons.

[psxphill]

An original unexpanded 500, 1000 or 2000 isn't much better.

There are some ok Atari ST games and some ST games were ported to the Amiga without making many changes. The top Amiga games were much better on the Amiga though (for example https://www.youtube.com/watch?v=yNGXuQKSjhI)

The Sega Genesis came out some 3 years later than the Atari ST with more powerful hardware (plus its a computer vs console).

The major difference is it used a sprite and tile engine rather than bitmaps. Tiles work great for games, not so well for word processors.

[matthey]

There are some ok Atari ST games and some ST games were ported to the Amiga without making many changes. The top Amiga games were much better on the Amiga though (for example https://www.youtube.com/watch?v=yNGXuQKSjhI)

I was talking about the general utility of the Amiga 500, 1000 and 2000 systems and not just games. In their minimum configurations, they were bottled up so that the advantages of the custom chips and multitasking did not shine. Early AmigaOS 1.x wasn't that great either. Add fast memory, an HD and a newer version of AmigaOS and they start to shine. The Amiga definitely had more potential than the Atari ST but cost more too. Shadow of the Beast probably needs 1MB of memory and maybe a fat Agnus where most early Amigas came with 512kB and the old Agnus.

[psxphill]

Shadow of the Beast probably needs 1MB of memory and maybe a fat Agnus where most early Amigas came with 512kB and the old Agnus.

Some people online claim they were able to run shadow of the beast on an a1000. Whether it was unexpanded or not is another matter.

Graphically it should be doable on an unexpanded amiga as it's mostly just a copper list, but I don't believe you could match it on an ST no matter what you did to it.

[vince_6]

Some people online claim they were able to run shadow of the beast on an a1000. Whether it was unexpanded or not is another matter.

There was a cracked 512K only version too.

[Thorham]

What does the Atari ST have to do with any of this?