Questions regarding 030 + CE accuracy

vagrant · 21 March 2014, 05:19

I know that traditionally 020 CE is more accurate than 030 CE, which is why I use it by default.
Toni I remember you mentioning something about newly acquired information on the 030 that could potentially increase accuracy, although i don't remember exact details.. and I *think* you've already begun to implement some changes.

Some questions:
Could 030 potentially surpass the 020 on accuracy? Or has it already?
030+CE CPU frequency seems to default at 8x (~28Mhz), would 40/50Mhz be a better default?
Does enabling MMU decrease accuracy or affect speed?

Toni Wilen · 21 March 2014, 19:47

020 will be more compatible in future. Someday I'll connect 68020 A1200 accelerator to ACA500 which is connected to my logic analyzer A500 and use it to examine CPU timings, Motorola documentation does not really explain cycle usage very well. (A500 because it is 16-bit and does not use surface mount chips).

030 CE is 020 CE + 030 new features (write buffer, faster memory accesses, data cache).

MMU and cycle-exact can't be enabled at the same time. Maybe in future.

8x is the default because power of 2 clock rate multipliers (of DMA clock) are faster to emulate.

vagrant · 22 March 2014, 02:01

Excellent, thanks for the explanation

21 March 2014, 05:19	#1
vagrant Registered User Join Date: Mar 2012 Location: Australia Age: 44 Posts: 1,126	Questions regarding 030 + CE accuracy I know that traditionally 020 CE is more accurate than 030 CE, which is why I use it by default. Toni I remember you mentioning something about newly acquired information on the 030 that could potentially increase accuracy, although i don't remember exact details.. and I think you've already begun to implement some changes. Some questions: Could 030 potentially surpass the 020 on accuracy? Or has it already? 030+CE CPU frequency seems to default at 8x (~28Mhz), would 40/50Mhz be a better default? Does enabling MMU decrease accuracy or affect speed?

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21 March 2014, 19:47	#2
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	020 will be more compatible in future. Someday I'll connect 68020 A1200 accelerator to ACA500 which is connected to my logic analyzer A500 and use it to examine CPU timings, Motorola documentation does not really explain cycle usage very well. (A500 because it is 16-bit and does not use surface mount chips). 030 CE is 020 CE + 030 new features (write buffer, faster memory accesses, data cache). MMU and cycle-exact can't be enabled at the same time. Maybe in future. 8x is the default because power of 2 clock rate multipliers (of DMA clock) are faster to emulate.

22 March 2014, 02:01	#3
vagrant Registered User Join Date: Mar 2012 Location: Australia Age: 44 Posts: 1,126	Excellent, thanks for the explanation

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