Boosting STFM: 16MHz bus, 64MHz Shifter

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exxos
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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by exxos » Wed Oct 11, 2017 9:14 pm

Congrats :dualthumbup:

Not sure why RAM access is 100% ? Possible the overhead from the extra resolution causing it ? I guess only way to find out is to do the DE mod.. Though still would expect RAM to be 200%.. The CPU is running at double speed with the MMU & RAM, so bit odd that.

I never checked the sync of the 161, looks to clock on the rising edge and says rising in the pdf after a quick look, your LA seem to clock on the 32mhz HI, so would seem to be all correct I think , glad it proved it could work though! I can add that into the next booster logic now I know it works :)

This probably GB3, even so...

Image

.. I don't think its routines would "fake" 200%... GB6 has much better routines, but don't think it would be 100% "out"...

Half asleep here, but my first thought is the MMU would trigger DTACK double speed, CPU would read at double speed.. nothing to generate waitstates unless the CPU totally missed DTACK for ages. Even if it missed by half a clock cycle, would still expect 150% or more.

So my initial thought is the extra resolution must be hogging MMU time with display updates, and lowering the RAM speed test back to 100%..

Wonder if you could simply load GB6, and disconnect the DE signal, screen will not update of course, but if you leave the signal disconnected (tie to 0v) just for testing, press "A" to run all tests, then wait a couple of moments, and reconnect DE , then you can see the results.. might even get 400% then ;) Idea being just to "turn off" the shifter requesting MMU time..
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troed
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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by troed » Wed Oct 11, 2017 9:37 pm

So I'll just leave this here ...
1280_400_2.jpg
1280_400_2.jpg (926.7 KiB) Viewed 348 times
640_200_16.jpg
640_200_16.jpg (1.25 MiB) Viewed 348 times

:twisted: :twisted: :twisted: :twisted: :twisted: :twisted: :twisted: :twisted:

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exxos
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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by exxos » Wed Oct 11, 2017 9:46 pm

troed wrote:
Wed Oct 11, 2017 9:37 pm
So I'll just leave this here ...
:cheer: :cheer: :cheer: :cheer:

God like!, 16 colours in medium res!

EDIT, oh nope, its actually higher than medium res!

Also 1280 x 400 2 colours :twisted:

EDIT2:

hold on, how did we get from extra res to extra colours as well ???
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troed
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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by troed » Wed Oct 11, 2017 9:57 pm

exxos wrote:
Wed Oct 11, 2017 9:46 pm
hold on, how did we get from extra res to extra colours as well ???
All horisontal resolutions become double :)

low: 320x200x16 -> 640x200x16
medium: 640x200x4 -> 1280x200x4
high: 640x400x2 -> 1280x400x2

(I don*t think the higher resolution should lower RAM speed btw, the MMU always interleaves CPU/Shifter access to memory no matter if DE is high or not. So, I do think the CPU stalls every second RAM access or so .. but .. that's for another day ;) Now I'm going to be a bit happy about the new video modes. My idea to patch the old overscan3 sources worked out fine after having debugged a bug that showed up for our resolutions)

/Troed
Last edited by troed on Thu Oct 12, 2017 10:01 am, edited 1 time in total.

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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by exxos » Wed Oct 11, 2017 10:06 pm

troed wrote:
Wed Oct 11, 2017 9:57 pm

All horisontal resolutions become double :)

low: 320x200x16 -> 640x200x16
medium: 640x200x4 -> 1280x200x4
high: 640x200x2 -> 1280x400x2

(I don*t think the higher resolution should lower RAM speed btw, the MMU always interleaves CPU/Shifter access to memory no matter if DE is high or not. So, I do think the CPU stalls every second RAM access or so .. but .. that's for another day ;) Now I'm going to be a bit happy about the new video modes. My idea to patch the old overscan3 sources worked out fine after having debugged a bug that showed up for our resolutions)

/Troed
ahh makes sense now :)

Yes, pat on the back to you for sticking with it and getting it working! You have a machine to get started with the software, that's the main thing. Leave the screwy booster stuff to me to figure out another day ;) :lol: :roll:
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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by rpineau » Thu Oct 12, 2017 4:46 am

Impressive !
:D

ube
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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by ube » Thu Oct 12, 2017 9:11 am

:shock: NICE!

Now for the important stuff; has V-sync pulsewidth changed? Do I need to update some code for the ubeswitch? ;)

troed
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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by troed » Thu Oct 12, 2017 9:18 am

Tests run with the latest GEMbench 6 - it's great to see programs not checking video mode ("low") but the fact that the resolution (640*200 - although there seems to be an off-by-one error in the detection) is good enough to run :D

I'm still sure RAM should be 200% once everything has been tuned correctly, but it's great to see the increased color depth doesn't have a huge impact on performance. A booster that includes these video modes will probably make 640x200x16 the most popular mode I think.
IMG_20171012_101235.jpg
IMG_20171012_101235.jpg (1.14 MiB) Viewed 329 times

@ube - GLUE still runs at 8MHz so nothing should've been changed when it comes to video timings. I'm currently using the previous version with physical mono/color switch, will change to the new one but I'm sure it works fine.

/Troed

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IngoQ
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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by IngoQ » Thu Oct 12, 2017 10:58 am

Woah... :excited: :bravo:
Ingo :geek:

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mikro
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Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Post by mikro » Thu Oct 12, 2017 12:03 pm

Wow, cool stuff Troed. Really impressive how such an easy (relatively speaking) mod can do so much. I wonder why nobody has similar idea for decades?

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