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AuthorTopic: Motorola 68060 FPGA replacement module (idea)  (Read 26984 times)

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Offline ChaosLord

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #30 on: January 06, 2013, 05:16:07 PM »
Quote from: psxphill;721484
http://en.wikipedia.org/wiki/DDR3_SDRAM#JEDEC_standard_modules
 
It looks like 1066mhz is the fastest standard I/o clock speed & 266mhz for the memory clock speed, but the latency's are huge. This isn't a problem if you can prefetch and burst fill your cache. You get 64bits per transfer per module as well.
 
It doesn't sound like much, but compared to chip ram or the memory in your 90's accelerator. It is pretty quick.


For randomly accessing memory your speed is 266Mhz / 16 = 16.625Mhz which is the same speed as the memory u already have on your Amiga accelerator card.

You only get good speed when writing a bunch of bytes in a straight line.  Even then it is really really hard to achieve over 500 MT/s since your memory controller must designed by a 200th TechMage.

This is why cache inside the CPU is dramatically important.
Wanna try a wonderfull strategy game with lots of handdrawn anims,
Magic Spells and Monsters, Incredible playability and lastability,
English speech, etc. Total Chaos AGA
 

Offline freqmax

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #31 on: January 06, 2013, 05:42:33 PM »
Quote from: ChaosLord;721489
designed by a 200th TechMage.


What do you mean with that? ;)
 

Offline Mrs Beanbag

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #32 on: January 06, 2013, 05:45:17 PM »
I see the problem with random access now... put simply, you have to read or write a whole block of data whether you want it all or not.

Just looking at the price of FPGAs. Can get a 550MHz Virtex 5 for just under £100, not bad. And it has >200k of block RAM!

Now I only have to learn VHDL...
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Offline freqmax

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #33 on: January 06, 2013, 05:54:52 PM »
100 GBP.. seems they have fallen.

But the main pain is the chip package...!
 

Offline Mrs Beanbag

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #34 on: January 06, 2013, 06:02:22 PM »
It is this LX one:
http://uk.farnell.com/jsp/displayProduct.jsp?sku=1876187&CMP=e-2072-00001000&gross_price=true
Others in the range seem a lot more expensive.

True I wouldn't want to try soldering one. Maybe you can buy sockets.
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Offline psxphill

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #35 on: January 06, 2013, 06:31:11 PM »
Quote from: ChaosLord;721489
For randomly accessing memory your speed is 266Mhz / 16 = 16.625Mhz which is the same speed as the memory u already have on your Amiga accelerator card.

I think the latencies are based on the io bus clock, not the memory clock. So it's not 266/16, it's 1066/16. The reasons why the latencies get higher is because of the increasing gap between the two clocks. The computer is using the io bus clock, so it makes sense for it to be based on that.
 
Old ram from the 90's also has page setup times. Fast page mode and static column were equivalent to how memory is accessed now, if you were accessing data in different pages then you had the latency. Because of this the 030/040/060 can burst reads from ram a cache line at a time. http://en.wikipedia.org/wiki/Dynamic_random-access_memory#Fast_page_mode_DRAM_.28FPM_DRAM.29
 
Ram is wider now than it was, so if you were creating a 68k memory controller with DDR3 then you'd keep reading the entire page from the ram all the time there was no other memory access required. You've paid for the entire page to be read, it just needs to be transferred and that bus can run up to 1066mhz. Even if the code does random access memory often, which would make you want to stop caching other data, the page is more likely to still be open compared to old 90's memory as it's bigger (like 256 bytes).
 
http://en.wikipedia.org/wiki/Prefetch_buffer
 
Suggesting that modern ram is the same speed as old ram is wildly missing the point. It's a lot more complex to interface to, but if you could hook up ddr3 to a 68060 then it would run quicker.
« Last Edit: January 06, 2013, 07:06:40 PM by psxphill »
 

Offline matthey

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #36 on: January 06, 2013, 06:49:18 PM »
Quote from: ChaosLord;721489
... designed by a 200th TechMage.

Quote from: freqmax;721492
What do you mean with that? ;)

I think he means 200th level TechMage. You must not have played D&D as a child.

@TCL
I thought the N050 only implemented write-through caches which are much easier to implement than copyback. They have excellent compatibility and the little bit faster modern memory would make up for some of the speed deficit. I agree that at least write-through caches for both instruction and data is needed. Anyone saying otherwise should turn off their accelerator caches and experience 68000 performance all over again ;).
 

Offline ChaosLord

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #37 on: January 06, 2013, 07:10:08 PM »
Quote from: Mrs Beanbag;721493

Just looking at the price of FPGAs. Can get a 550MHz Virtex 5 for just under £100, not bad. And it has >200k of block RAM!

Now I only have to learn VHDL...


You can do it!  You are Mrs. Beanbag! ;)
Wanna try a wonderfull strategy game with lots of handdrawn anims,
Magic Spells and Monsters, Incredible playability and lastability,
English speech, etc. Total Chaos AGA
 

Offline ChaosLord

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #38 on: January 06, 2013, 07:27:01 PM »
Quote from: matthey;721503
I think he means 200th level TechMage.

+1


Quote

@TCL
I thought the N050 only implemented write-through caches which are much easier to implement than copyback.

True.



Quote

 They have excellent compatibility and the little bit faster modern memory would make up for some of the speed deficit. I agree that at least write-through caches for both instruction and data is needed. Anyone saying otherwise should turn off their accelerator caches and experience 68000 performance all over again ;).


Anything written in C really needs copyback caches.  So does everything else for that matter.  Tons of code accesses vars on the stack over and over and over again.  I love my copyback cache. :knuddel:

I used to do lha timing tests on my 25Mhz 030 vs. my 25Mhz 040.  My 040 was always 3x the speed.  3x.  According to the timing charts of the basic instructions it should have been 2x the speed.  I conclude the rest of the performance increase came from the copyback cache.

Back in those days lha was written in asm by a competent coder.  And the copyback cache managed to give a magical 50% performance boost. :cool:
Wanna try a wonderfull strategy game with lots of handdrawn anims,
Magic Spells and Monsters, Incredible playability and lastability,
English speech, etc. Total Chaos AGA
 

Offline Iggy

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #39 on: January 06, 2013, 08:44:22 PM »
Why not just build an adapter with an X86 processor equipped with very fast
JIT interpretation?
"Not making any hard and fast rules means that the moderators can use their good judgment in moderation, and we think the results speak for themselves." - Amiga.org, terms of service

"You, got to stem the evil tide, and keep it on the the inside" - Rogers Waters

"God was never on your side" - Lemmy

Amiga! "Our appeal has become more selective"
 

Offline ChaosLord

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #40 on: January 06, 2013, 08:50:03 PM »
Quote from: ChaosLord;721489
For randomly accessing memory your speed is 266Mhz / 16 = 16.625Mhz which is the same speed as the memory u already have on your Amiga accelerator card.

You only get good speed when writing a bunch of bytes in a straight line.  Even then it is really really hard to achieve over 500 MT/s since your memory controller must designed by a 200th TechMage.

This is why cache inside the CPU is dramatically important.


My previous calculation was totally wrong.  As near as I can tell the correct calculation should be:

For randomly accessing memory your speed is 266Mhz / 4 = 66.5Mhz

You only get good speed when reading/writing a bunch of bytes in a straight line.  Even then it is really really hard to achieve over 500 MT/s since your memory controller must be designed by a 200th level TechMage because you cannot simply issue sequential memory requests.  In order to reach the theoretical maximum you must keep 4 memory requests in-flight at all times.

This is why cache inside the CPU is dramatically important.
Wanna try a wonderfull strategy game with lots of handdrawn anims,
Magic Spells and Monsters, Incredible playability and lastability,
English speech, etc. Total Chaos AGA
 

Offline psxphill

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #41 on: January 06, 2013, 08:51:34 PM »
Quote from: ChaosLord;721514
You only get good speed when reading/writing a bunch of bytes in a straight line.

That is exactly what cache bursting is for. It's as true now as it was in the 90's.
 

Offline ChaosLord

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #42 on: January 06, 2013, 08:52:37 PM »
Why not just build an adapter with an ARM processor equipped with very fast
JIT interpretation?
Wanna try a wonderfull strategy game with lots of handdrawn anims,
Magic Spells and Monsters, Incredible playability and lastability,
English speech, etc. Total Chaos AGA
 

Offline JimDrew

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Re: Motorola 68060 FPGA replacement module (idea)
« Reply #43 on: January 06, 2013, 09:06:16 PM »
I am curious why there is some idea of a shortage of 68060 chips?  There are tens of thousands of these chips, both 50MHz and 60MHz (MC and XC versions) available from suppliers in China.  These were used in the Northern Telecom call center boards.  There is a thread here about this.  Just pull the chip with the heat sink and put it in your Amiga (or replay) board.

eBay has a slew of these boards, for about 1/2 of what 68060's by themselves are selling for.
 

Offline psxphill

Re: Motorola 68060 FPGA replacement module (idea)
« Reply #44 on: January 06, 2013, 09:19:21 PM »
Quote from: JimDrew;721517
I am curious why there is some idea of a shortage of 68060 chips? There are tens of thousands of these chips, both 50MHz and 60MHz (MC and XC versions) available from suppliers in China.

The shortage is only because we're looking for the rare versions with the bugs fixed & sellers in china are remarking chips to say they are the latest mask (71E41J) when they are not. The real ones can be clocked over 100mhz.
« Last Edit: January 06, 2013, 09:27:11 PM by psxphill »