Falcon's 16bit bus myth - 32bit vs 16bit war

[Frank B]

The 1200 CPU access to chip RAM is the same as the 500 at 7 mhz but with a 32 bit bus. On 32 bur accesses they'll be about the same but fotr 16 bit accesses the falcon should be faster.

[mikro]

Indeed, both machines are pretty crippled when it comes to RAM access. In the end, I think we are a bit better -- even with a 1000 MHz accelerator, you still have to write to chip RAM which is slower than our ST RAM. That (and the fact that CT60 has much faster TT RAM access) makes the Amiga demos so much faster on Falcon.

[Cyprian]

The 1200 CPU access to chip RAM is the same as the 500 at 7 mhz but with a 32 bit bus. On 32 bur accesses they'll be about the same but fotr 16 bit accesses the falcon should be faster.

Chip Ram in all Amigas is clockes with 3,5MHz.
The Amiga design is that the CPU have access to all chip Ram bus slots (even and odd) but it needs minimum two Chip bus cycles to access the Chip Ram.
Therefore it gives 1,79 million accesses per second, 16bit in case of A500/1000/2000 and 32bit in case of 1200/3000/4000.

IIRC interesting is that A3000 Chip Ram memory performance is similar to A500, not to A1200.

Fast Ram is another story.

[Badwolf]

If you compare a default Falcon 030 (which does not have a 32-bit data path to RAM without an accelerator) to an Amiga 1200 with a 32-bit FAST RAM expansion in the trap door -- NO accelerator -- isn't it the case the the Amiga can access RAM (its CPU) faster than that of the Falcon?

In short: the stock Falcon and the Stock A1200 can access (bulk*) memory at about the same speed (~12% speed difference in favour of the Falcon) but the minute you put FastRAM in the A1200 it can access it (and consequently run) a lot quicker than the Falcon.

The Falcon needs a CPU replacement card to receive a true FastRAM equivalent upgrade.

BW

* AIUI, the Falcon can access non-adjacent words faster than the A1200, so the above is only true for bulk memory accesses. The Falcon will benchmark similarly but 'feel' considerably faster in every day use. When you plug FastRAM in the 1200's trapdoor, the situation reverses starkly.

[Cyprian]

The Falcon needs a CPU replacement card to receive a true FastRAM equivalent upgrade.

it is a pity that there is no real the Fast Ram port in the Falcon

* AIUI, the Falcon can access non-adjacent words faster than the A1200, so the above is only true for bulk memory accesses.

in case of Falcon, byte access and word access (word boundary aligned) will be almost twice faster than on A1200

[calimero]

Ok. I'm sorry (maybe?) for reviving this thread, but I've read it all and I can't QUITE see the answer to this:

If you compare a default Falcon 030 (which does not have a 32-bit data path to RAM without an accelerator) to an Amiga 1200 with a 32-bit FAST RAM expansion in the trap door -- NO accelerator -- isn't it the case the the Amiga can access RAM (its CPU) faster than that of the Falcon?

I wonder this too
I guess answer is that Amiga 1200 with FastRAM is:
- At least twice as fast as Falcon (in CPU to RAM read/write speed) plus
- CPU will be no blocked by video output (which can eat as much as 30% (?) of CPU RAM access on Falcon (in True color mode))

I also wonder if Amiga 1200 support Burst mode with FastRAM?

Btw
I do have Amiga1200 with FastRAM only board so guess I should run some test on it?

[Cyprian]

I do have Amiga1200 with FastRAM only board so guess I should run some test on it?

Is it stock 1200 with 68EC020 plus Fast Ram?
Can you run "BusSpeedTest 0.19" on it?

[elliot]

Okay I can not seem to find this out (I think I am asking the wrong question), the A1200 has a 68020 which has 24bit addressing but does it have a 24bit bus lines OR 16bit? This is specific to the CPU/architecture of the A1200 as I assume there are variants of the CPU.

[robinsonb5]

Okay I can not seem to find this out (I think I am asking the wrong question), the A1200 has a 68020 which has 24bit addressing but does it have a 24bit bus lines OR 16bit? This is specific to the CPU/architecture of the A1200 as I assume there are variants of the CPU.

There are variants of the CPU, and a full 68020 has a 32-bit address bus for a 4 gig address space. The A1200 has a 68EC020 which has 24 address bits, and thus a 16 megabyte address space. All 24 bits are exposed on the expansion bus, so that a Fast RAM expansion can map itself to an appropriate place in memory - typically 0x200000. (The actual data bus is 32 bits wide, of course, whichever variant of 68020 is used.) Hope that helps

[Cyprian]

Okay I can not seem to find this out (I think I am asking the wrong question), the A1200 has a 68020 which has 24bit addressing but does it have a 24bit bus lines OR 16bit? This is specific to the CPU/architecture of the A1200 as I assume there are variants of the CPU.

68ec020 has 24bit address lines and 32bit data lines

[elliot]

Interesting, so it is the same as the 68000 in that the registers can (logically) address 32 bits in the instructions but physically anything above 24bits would be mapped to hi-mem hardware registers or other? Not sure if Amiga used that concept?

The falcon had a 16bit bus right so was that 32bits cut in halve (two cycles of bus) OR was it also limited to single 16bit bus and so memory? In which case, what 68030 did it use?

I think there was a 68008 or something which I think was used in the Sinclair QL which was a 32bit CPU with 8bit bus, again not sure if that was 8bit x 2 or simply 8bit.

Was the 24bit bus the only limitation of the 68EC20?

[elliot]

I always felt that the Falcon out-spected the A1200, 16Mhz over 14mhz, 68030 over 68020 plus it had a DSP at 32Mhz for music and the A1200 only had the same 8bit 4chan playback of an A500 (with maybe some playback rate increase). Not to mention that the DSP could do other crap too. I do know that A1200 had sprites, blitter (or was it just for compatibility like the Falcon), copper (I assume) and other things but not sure that made up for it? Did it also have a rudimentary chunky to planner mode too? I can see that being useful. Did it still have background/foreground screens and where they limited to the A500 or where they enhanced?

I can also see that fastram on the A1200 would be really help with e.g. compression, 3d calcs, etc but does that compete with a whole extra fast (was the DSP risc) CPU V sprites and blitter?

What do we think here or is it just too close?

[calimero]

I do have Amiga1200 with FastRAM only board so guess I should run some test on it?

Is it stock 1200 with 68EC020 plus Fast Ram?
Can you run "BusSpeedTest 0.19" on it?

How to use bustest ?!
Without arguments I get error "no test selected"

In documentation it state e.g. "bustest fast chip rom" - but than I get "wrong number of arguments"

EDIT:
bustest arguments are case sensitive!

ok.
I try it on my Amiga 1200 with M-TEC A1200 Speeder card but it seems that FastRAM is not recognised. When I run bustest FAST I do not get any results.
I got this M-Tec card but I never use it before. I am not sure if it is working. There are three jumpers on board, all four simm slots are populated...
I boot Amiga with floppy only and I put only bustest on it. I suppose that M-Tec A1200 does not require any drivers?

I can not find documentation for it on internet.

[rudis]

http://amiga.resource.cx/search.pl?id=mtec1230

[calimero]

I manage to start M-TEC A1200 Speeder (Autoconfig manufacturer ID: 2192, Product: 5) with 4MB FastRAM - I simple push it little bit left/right and it starts to work!

So this are results (I run two times each test and results are consistent):

m-tec A1200 slow.jpg

m-tec A1200 fast.jpg

m-tec A1200 rom.jpg

FastRAM in plain Amiga1200 is more than twice fast as chip RAM.


btw
what are readm and writem values in bustest ?!?

[Cyprian]

Thanks @calimero

Code: Select all

BusSpeedTest 0.19

chip    readl     3.9 MB/s
chip    writel    13.4 MB/s
fast    readl     6.9 MB/s
fast    writel    13.4 MB/s

Interesting result is for chip readm vs readl

Code: Select all

chip    readm     5.7 MB/s

Is it stock 14MHz 68ec020 Amiga or accelerated one?
I see spec for M-Tec A1200
"can be clocked either synchronously (14.28 MHz) or asynchronously (up to 50 MHz with oscillator"
http://amiga.resource.cx/exp/mtec1200

[Moulinaie]

If Atari had based the Falcon on the TT... 32MHz, Fast Ram, this would have been cool.
A TT with a DSP and a True Color mode.

Guillaume.

[1st1]

Check for Falcon Microbox... That would have been my favorite machine...

[Badwolf]

Anyone with an A1200 + Fastmem (but not a CPU booster)?

The best comparison would be to boot up EmuTOS and run Nembench.

BW

[calimero]

It should be stock 68ec020 @14MHz. What is the best way to check? To open Amiga 1200?

What is readm?
Readw is: read Word
Readl is: read Long word
right?
What is readm?!?

Regarding M-Tec: "can be clocked either synchronously (14.28 MHz) or asynchronously (up to 50 MHz with oscillator" - this refer to FPU clock!!

[Cyprian]

Thanks for clarification.

I guess readm/writem means "movem" instruction

[calimero]

Anyone with an A1200 + Fastmem (but not a CPU booster)?

I

The best comparison would be to boot up EmuTOS and run Nembench.

What version of Nembench should I use?

[Badwolf]

Calimero: aha, I wasn't sure if your M-Tec card was an external CPU or not.

Anyway, Nembench 2.1 seems to be the lastest version I could find from a quick scout around: https://milan.kovac.cc/atari/software/? ... MBENCH.FTP

Of course, this is with me guessing that EmuTOS can detect the FastRAM in the A1200. This looks to be the case, however: https://github.com/emutos/emutos/blob/m ... floppy.txt

Here's the floppy download page. https://sourceforge.net/projects/emutos ... p/download

Good luck -- it should provide a proper 1:1 comparison with whatever Falcons are out there. Best to do it in ST-High video mode.

BW

[calimero]

Calimero: aha, I wasn't sure if your M-Tec card was an external CPU or not.

Anyway, Nembench 2.1 seems to be the lastest version I could find from a quick scout around: https://milan.kovac.cc/atari/software/? ... MBENCH.FTP

From my site

Although there is also updated version by DLM here on forum...

Of course, this is with me guessing that EmuTOS can detect the FastRAM in the A1200. This looks to be the case, however: https://github.com/emutos/emutos/blob/m ... floppy.txt

Here's the floppy download page. https://sourceforge.net/projects/emutos ... p/download

Good luck -- it should provide a proper 1:1 comparison with whatever Falcons are out there. Best to do it in ST-High video mode.

BW

I download ADF, put it on floppy and on Amiga 1200 with 040 and PPC Blizard (one that I use for everyday since it have installed Amiga OS 3.1) I see that EmuTOS try to run after reset from floppy but I get scrabbled screen.

IMG_3514.jpg

On Amiga 1200 with M-Tec (one that we want to test) - it wont read same floppy!
Probably I should try again to create Floppy from ADF...

[czietz]

I highly doubt NEMBENCH will run on the Amiga, even under EmuTOS. Afaik, NEMBENCH directly accesses the MFP for accurate time measurements - and this will obviously not work an an Amiga.