SUGGESTIONS

All information relating to the Alpha plus all the WIP threads etc.
chlu600
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Re: SUGGESTIONS

Post by chlu600 »

One feature that I havn't seen in this topic is tile-based background graphics. I've always wanted such a feature in the ST/E. Because it opens up for both better games and interesting demo effects, see the C64-scene and their charater mode.
A shifter with small amount of video ram for those assets and some mapping data. Of cource with a seperate 16 colour palette and possibility to set vertical and horizonal offset by one pixels steps. The first color in the ordinary palette has background transparency if background is defined.

More of day dreaming - but useful back in the days I think 😃
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exxos
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Re: SUGGESTIONS

Post by exxos »

chlu600 wrote: Tue Aug 21, 2018 10:48 pm A shifter with small amount of video ram for those assets and some mapping data.
Thats what I was talking about earlier... shifter with video ram.. but loads of other stuff aswell relating to it... like with a frame buffer, you would have the option to only update parts of the frame, not the whole lot.. kinda like how video only updates bits which move. But Smonson is going to add more video modes, but would be a huge re-code and job to redo the shifter with its own RAM.

Its why I was more thinking manipulating the MMU instead.. at least a "quick wipe" could be done.. also dont forget the blitter will be running 50MHz as well...
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KyleB
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Re: SUGGESTIONS

Post by KyleB »

Been thinking a while about the ram being a falcon board. Not sure that's a good idea, I mean I get the basic principle - all falcs are 14mb these days it seems so why not recycle - but not sure that these 4MB boards are going to be all that plentiful anymore after 25 years of being chucked in the bin.

Is there not some 4MB ramchip that will work in an ST circuit? Or even just one 4mb simm, seems easy enough to find on ebay especially laptop stuff.
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Re: SUGGESTIONS

Post by exxos »

KyleB wrote: Tue Aug 28, 2018 1:11 am Been thinking a while about the ram being a falcon board. Not sure that's a good idea, I mean I get the basic principle - all falcs are 14mb these days it seems so why not recycle - but not sure that these 4MB boards are going to be all that plentiful anymore after 25 years of being chucked in the bin.

Is there not some 4MB ramchip that will work in an ST circuit? Or even just one 4mb simm, seems easy enough to find on ebay especially laptop stuff.
You need to read everything which has been said... The next revision will have a new MMU with SRAM, so will be all SMT stuff. Of course there will be always some chip impossible to find in years to come.. Frankly, in 25 years time it can be someone else's problem.

This board is a Alpha, its proof the design can/will work, everything else is a bit irrelevant at this point anyway.
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KyleB
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Re: SUGGESTIONS

Post by KyleB »

Fair enough... It's spread about through enough threads I'm never reading it in the right order
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exxos
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Re: SUGGESTIONS

Post by exxos »

I used the Falcon RAM boards as they was on evilbay for £5 when I designed the board, they hadn't sold for months, So I used them. Unfortunately they since all vanished and I regret not buying them all. Problem was the STF board was sat idle for many months as I had not had time to work on it. The result is no easy to find RAM cards anymore. Of course is not a good idea "now", but it was 12 months ago.

As said many times, the card will not be used on later revisions anyway. After I have got the FPGA blitter under control, the MMU is next. Wolfgang did a MMU core with SRAM. So the Falcon RAM card will not be used at all then.

I have been talking to wolfgang also about adding a fast block clear function into the MMU. Of course someone will have to code a benchmark routine to compare CPU clear, Blitter clear and MMU clear to see if its faster or not. It should be, the CPU would only have to do 2 or 3 bus cycles to run a block clear in RAM. I'm assuming blitter and CPU would have to clear RAM byte by byte.. which would take up thousands of bus cycles. Of course I am not a expert programmer.. so maybe someone else knows more about how many cycles things take.

We must also think the new MMU can run much faster than the CPU.. with 10ns SRAM, plus FPGA delays, It should be able to clear ram many times faster with such speeds. It may not be much faster with a stock 8MHz system.. it would have to be benchmarked. Though this could be easy adaption for screen clear in games.. and maybe some things in TOS could be patched for faster screen clear with new MMU.

It could be possible to run the whole system at 8MHz, but use for example 100MHz speeds for screen clear. I don't know if that would break raster stuff still with a faster screen clear ?
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troed
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Re: SUGGESTIONS

Post by troed »

exxos wrote: Tue Sep 11, 2018 4:22 pmI don't know if that would break raster stuff still with a faster screen clear ?
It would have to be addressed in a new way to not break old code.
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Re: SUGGESTIONS

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troed wrote: Tue Sep 11, 2018 5:03 pm
exxos wrote: Tue Sep 11, 2018 4:22 pmI don't know if that would break raster stuff still with a faster screen clear ?
It would have to be addressed in a new way to not break old code.
I can only really think that the CPU will have to write start and end address of block to clear into a register. Then the MMU will clear that block, and likely send DTACK to CPU when clear is finished.
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troed
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Re: SUGGESTIONS

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exxos wrote: Tue Sep 11, 2018 5:05 pm I can only really think that the CPU will have to write start and end address of block to clear into a register. Then the MMU will clear that block, and likely send DTACK to CPU when clear is finished.
Exactly. That wouldn't break any existing code (bar any miswrites to that previously not used register of course).
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Re: SUGGESTIONS

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troed wrote: Tue Sep 11, 2018 5:28 pm Exactly. That wouldn't break any existing code (bar any miswrites to that previously not used register of course).
I guess patched code could check the register to see if a write fails or something.. Then it knows if its running on the new MMU or not... or just separate patched versions of software :shrug:
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