V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Help & information about the V2.X series boosters.
Atarian Computing
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by Atarian Computing » Thu May 31, 2018 4:44 am

Thanks for the benches. Wow, so I was expecting a bigger difference. So this mofo will be a scorching fast booster!

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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by exxos » Thu May 31, 2018 8:28 am

Atarian Computing wrote:
Thu May 31, 2018 4:44 am
Thanks for the benches. Wow, so I was expecting a bigger difference. So this mofo will be a scorching fast booster!
If ran from fast-ram yes... The STE can beat most scores at 32MHz, but can't speed up ST-RAM.. TT shows almost 250% there.
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by exxos » Thu May 31, 2018 2:38 pm

After looking at some scope images of E-clock it hardly ever goes high now and I think I can just emulate it a lot easier than the normal methods of emulating E-clock..

So my investigation showed that when VPA goes low, about 200ns later VMA goes low.. But then there is a huge delay of 1,000NS before the ACIA CS goes high (high is enabled). It seems GLUE is using the E-CLOCK to trigger the ACIA CS line..

So what I did was remove all the delays and E-CLOCK totally and just did this..

Code: Select all

VMA.CK = CLK8;
VMA.D = VPA;
!E = VMA;

CPU_DTACK = 'b'0;
CPU_DTACK.OE = !ST_DTACK
               # !VMA;
               
!AVEC =  FC2 & FC1 & FC0 & A19 & A18 & A17 & A16 & !VPA ;
So basically everything happens at the same time. !E will be asserted for one 8MHz clock cycle is approximately 125ns. The 6850 datasheet says the minimum HI time is 210ns... But we know we can double clocked these anyway so 100ns.. So it basically tallies up and seems to work fine.

This is of course running a stock 8MHz system just to prove works...

Though if I transfer these changes over to the 50MHz code, then in theory still works just the same... So I need to try :lol:
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by exxos » Fri Jun 01, 2018 4:03 pm

So this turned out far more annoying than I had originally anticipated :roll:

I have now redesigned the whole VPA,VMA,E based system and greatly simplified it. So now there is actually no "E-clock" as such, and the whole code generating the 40/60 clock is now gone.

Code: Select all

Z3.CK = CLK16;
Z3.D = E & !VMA5 & !VPA & !CPU_AS; 

VMA1.CK = CLK8; 
VMA2.CK = CLK8;  
VMA3.CK = CLK8; 
VMA4.CK = CLK8; 
VMA5.CK = CLK8; 

VMA1.D =  VPA # CPU_AS;
VMA2.D = VMA1 # VPA # CPU_AS;
VMA3.D = VMA2 # VPA # CPU_AS; 
VMA4.D = VMA3 # VPA # CPU_AS;
VMA5.D = VMA4 # VPA # CPU_AS;

!E = CPU_AS # VPA # VMA2;

VMA = VPA; 
Basically what happens is when VPA goes low for a ACIA cycle, VMA is also set low without any delay. What I can tell is VMA basically equates to the 6850CS which is output from GLUE which drives the 6850 CS line. There isn't really any need what I can see to add any delays on this. So when VPA goes low the ACIA CS line also goes low and enables the ACIA.

Now because of the setup time of the ACIA we need to wait around 500ns in total. So what I do is I wait 2 x clk8 cycles and then issue "E", is basically easier to understand as a output enable of the ACIA (but a bit more complicated than that).

So we select the ACIA by setting the CS low, two clocks later set Enable high which then outputs data onto the bus. But there is a setup time here also for the data to actually be valid. So I wait another 3 clock cycles and then issue DTACK via Z3.

So far this seems to be running very well for the past hour. Initially I did not have any delays on the "E" signal, and I had some intermittent crashes. The likely the ACIA may have a slight bus conflict with data on the bus from something else. So I just avoid this by delaying "E" couple of clock cycles. "E" and DTACK (Z3) are deselected when either CPU_AS or VPA goes high which terminates the cycle.

So from this there is no actual 40/60 E-clock anymore, simply used as "E" as a enable line only for the ACIA. Which is what actually the E-clock is for, but we do not need to constantly run this signal at 500KHz, its only asserted when we need it. So this greatly simplifies the code and how it all works.

Technically now the ACIA are running at a higher speed even if the CPU is running at a stock 8 MHz. I do not think this will be a problem compatible wise. The only side effect I know of this is where a sampled sound is playing and when you move the mouse the sound slows down. The effect will actually be less as the ACIA are running at a higher speed. So I do not see this as a problem.

So now I have the ACIA running from the system clock, I can now get back to overclocking the CPU over 50Mhz 8-)
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by exxos » Fri Jun 01, 2018 6:59 pm

55MHz!!! :twisted: :twisted: :twisted: :twisted:

55mhz.jpg
55mhz.jpg (120.15 KiB) Viewed 538 times
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Atarian Computing
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by Atarian Computing » Fri Jun 01, 2018 7:05 pm

exxos wrote:
Fri Jun 01, 2018 6:59 pm
55MHz!!! :twisted: :twisted: :twisted: :twisted:


55mhz.jpg
Dude, awesome. Remember this day.

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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by troed » Fri Jun 01, 2018 7:06 pm

Amazing. How hot does the CPU get?

(Thinking about how I had to put a heatsink on the Shifter when I run it at 64MHz)

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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by exxos » Fri Jun 01, 2018 7:11 pm

troed wrote:
Fri Jun 01, 2018 7:06 pm
Amazing. How hot does the CPU get?
Ambient is about 27c, CPU 36c.
Atarian Computing wrote:
Fri Jun 01, 2018 7:05 pm
Dude, awesome. Remember this day.
:thumbup:
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by exxos » Fri Jun 01, 2018 7:47 pm

58MHz!!! :twisted: :twisted: :twisted:

int-div from 566%(55mhz) to just shy of 600%!

.. and that's ya lot!

CPU doesn't seem to try to boot after 58MHz.. So think its safe to say that 68000 is maxed out now.. 8-) ... only took 5 years! :lol: :roll:

58mhz.jpg
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4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Post by rpineau » Fri Jun 01, 2018 8:23 pm

:bravo:
Working ones : MegaSTE (68020) / TT030 / Falcon with AB040 & Eclipse / 1040STF
Need testing : Falcon with CT2

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