New 65C02/W65C816 copro

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cmorley
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Re: New 65C02/W65C816 copro

Post by cmorley » Tue Aug 21, 2018 8:46 pm

Try as I might I can't get a 65C02 to run faster than 25MHz at 3.3v Vcc. It is rock steady and reliable at 25 Mhz but won't run BASIC at 26.5MHz. So it seems that although it will run a INC JMP loop at 35Mhz it won't run a complex branching program at that speed.

I tried all sorts of experiments with wait states but that's just the limit I think.

24MHz is still be 8x the original Acorn 2nd processor speed so not too shabby... 10x would have been better and if it had gone up to 11 then 8)

I'll have to go back to 5v if I want it to run faster.

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BigEd
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Re: New 65C02/W65C816 copro

Post by BigEd » Tue Aug 21, 2018 9:07 pm

That's pretty fast! It's not unexpected that some operations will take longer on-chip than others, so the critical frequency is not the same for all programs. It's not unusual to find the fastest and then back off a bit for safety. Or to test at slightly lower voltage and then raise the voltage back to nominal.

cmorley
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Re: New 65C02/W65C816 copro

Post by cmorley » Sun Jan 13, 2019 1:22 pm

I made another adapter board to see what I could get out of the WDC65C02 at 5v. A mod or two later this specimin is running at 33MHz from the BBC PSU. It'd go faster from an external & overvolt it a bit.

Still not too shabby!

Mandatory BASIC2 speed test results. It seems stable too.

Code: Select all

BBC BASIC CPU Timing Program
Real REPEAT loop        34.16MHz
Integer REPEAT loop     34.14MHz
Real FOR loop           31.21MHz
Integer FOR loop        34.23MHz
Trig/Log test           32.91MHz
String manipulation     34.47MHz
Procedure call          34.25MHz
GOSUB call              34.22MHz
Combined Average        33.63MHz
I can get 25Mhz stable at 3.3v so this is 32% boost on that.

I had to put a waitstate in to read mu ULA implementation at 33MHz. I can't hit 34Mhz though without crashing.
Last edited by cmorley on Sun Jan 13, 2019 1:22 pm, edited 1 time in total.

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1024MAK
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Re: New 65C02/W65C816 copro

Post by 1024MAK » Sun Jan 13, 2019 6:56 pm

=D>

Good to see you are still working on this 8)

Mark

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Re: New 65C02/W65C816 copro

Post by dominicbeesley » Mon Jan 14, 2019 1:27 am

Hear hear!

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