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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: lassie on August 21, 2012, 02:37:14 PM

Title: Amiga cpu
Post by: lassie on August 21, 2012, 02:37:14 PM

Hi guys i was thinking is the 68030 faster than the 68EC030? or is it the same. or what is the different between the 2 cpu

Title: Re: Amiga cpu
Post by: OlafS3 on August 21, 2012, 02:41:11 PM

i think it is without MMU. I do not think that this normally makes a difference

Title: Re: Amiga cpu
Post by: AmiBoy on August 21, 2012, 02:41:38 PM

The only difference is that the EC version of the CPU comes without an inbuilt MMU (memory management unit).

At the same clock frequency (i.e. same MHz) they process data at the same speed.

I don't think the Amiga in general ever took advantage of an MMU in any 68K CPU but I could be wrong.

AmiBoy

Title: Re: Amiga cpu
Post by: runequester on August 21, 2012, 02:42:41 PM

Quote from: lassie;704510

Hi guys i was thinking is the 68030 faster than the 68EC030? or is it the same. or what is the different between the 2 cpu

I know for the 020, the main, practical difference is the EC version only supports 8 MB RAM. I imagine the same would be the case for the 030

Title: Re: Amiga cpu
Post by: OlafS3 on August 21, 2012, 02:42:49 PM

a link:
http://stason.org/TULARC/pc/amiga/faq/1-1-What-are-68EC020-68EC030-and-68LC040.html

Title: Re: Amiga cpu
Post by: psxphill on August 21, 2012, 02:49:42 PM

Quote from: runequester;704513

I know for the 020, the main, practical difference is the EC version only supports 8 MB RAM. I imagine the same would be the case for the 030

The 68EC020 has a 24bit address bus, like the 68000. So it's 16mb minus roms & IO. On the A1200 you might have only been able to get 8MB fast ram, but you could probably squeeze some more in there.
 
The 68EC030 has a 32bit address bus. It's only difference is the lack of MMU.
 
EC just means it's cut down for embedded use.

Title: Re: Amiga cpu
Post by: runequester on August 21, 2012, 02:54:44 PM

I stand corrected. Thanks guys! :)

Title: Re: Amiga cpu
Post by: lassie on August 21, 2012, 04:15:10 PM

Thanks for your answers :)

Title: Re: Amiga cpu
Post by: Zac67 on August 21, 2012, 06:22:13 PM

The MMU was only ever used for ROM shadowing or for generating virtual memory (with extra tools).

Title: Re: Amiga cpu
Post by: matthey on August 21, 2012, 07:58:34 PM

Quote from: Zac67;704531

The MMU was only ever used for ROM shadowing or for generating virtual memory (with extra tools).

And for fixing the 68030 write allocate bug which is faster than the other solutions :D.

Quote from: Toni Wilen;772472

Second time today I post this link: http://amigadev.elowar.com/read/ADCD_2.1/AmigaMail_Vol2_guide/node0161.html

Quick explanation: 68030 data cache always caches long aligned writes, even if destination address is supposed to be uncacheable. Following read(s) from same address come from cache, not from memory that may have been modified by some DMA device.

AFAIK this can be only fixed by using MMU to mark required memory regions as uncacheable. (if CPU is non-EC)

Title: Re: Amiga cpu
Post by: Nostalgiac on August 21, 2012, 08:28:36 PM

Quote from: Zac67;704531

The MMU was only ever used for ROM shadowing or for generating virtual memory (with extra tools).

back way then I was glad with my full 030 on the A2630 as running the virtual memory solution (sorry, forgot which) was actually quite useful on my old setup.

Tom UK

Title: Re: Amiga cpu
Post by: commodorejohn on August 21, 2012, 08:55:56 PM

ROM shadowing's plenty handy too, especially with faster accelerators with onboard RAM.