Overclocking CPC @6/8 Mhz

[radu14m]

only 250, 300 and 500 can be set on my HxC.

[TFM]

Oh bad! Maybe the next firmware update could have 375 too?

[radu14m]

in the menu beside de 250,300 and 500 bitrate i have also the option to set the birate from the HFE file.
would this be a solution ?


did you manage to patch the FW for 6Mhz ?


Thanks TFM !

[TFM]

never cared about it. Did a FutureOS for 6 MHz. But still I have no monitor at my CPC yet. As soon as I have a new monitor I can take a look at the Firmware though.


Are you ok to have a firmware patch which enables the CRTC for 6 MHz when switching to "60 Hz", that would need you to integrate a switch into the CPC with two wires to the PCB at LK 4.


Or do you like a patch which is always active?

[radu14m]

well,  both solutions are fine but for long therm, even if i don"t like to another switch, the switching only @ "60 Hz" is better.
Thanks TFM   !!!


I alway wonder why the cpc-s have so many switches ! Now i understand 
Btw, it is possible to ask like for i.e. the cpc6128+ at start, to choose between 4 Mhz or 6 Mhz FW ?

[TFM]

Sure. Everything is doable, it depends how much time s.o. want's to put in.

[radu14m]

Thanks TFM !!!!

[zhulien]

On A500, this method (doubling the clock) allow a non sinificative gain. (around 15%)
Here, it's exactly the same... +50% speed allow 7% gain... Because, in both case, the RAM is not enough faster to take advantage on this hack.
You may have problem with the PPI too... Because, it will not work faster to drive properly the peripherals.

I am hoping with the GODIL spartin packages that RAM issue will be less of an issue, if it can be gotten to work at all... I intend to use the memory inside the FPGA as kind of 'fastRAM' like the Amiga but then would need normal speed transfers with new instructions into the CPC RAM for I/O.  I suspect even theoretically, the CPU could be like a dual CPU design too where an internal CPU will have a turbo mode for the internal fastRAM, and while it is doing that, it can output NOPs (remember your perfect project) to the outside World until it comes back out of turboMode.  Likely I wouldn't actually have 2 cores, but make the 1 core switch between normal CPC Z80 mode and internal turbo mode.  I'm not even sure 'yet' how much RAM i can get out of the GODIL after the core is in place...

[TotO]

A simple question...
Is someone had already tried to overclock a GX4000? (40MHz to 60MHz) 

[TFM]

A simple question...
Is someone had already tried to overclock a GX4000? (40MHz to 60MHz) 

Ok, this will not help much. But I think to remember that a 6128 Plus can run at 5, but not at 6 MHz. But I never tried it myself, because I don't like to solder them (Plus or GX), it's harder to exchange the crystal compared to the CPC6128.


But IMHO this experiment remains to be done. 

[TotO]

Why not at 6 MHz? The ASIC crash using a 60MHz clock? 

[TFM]

Why not at 6 MHz? The ASIC crash using a 60MHz clock? 

As I remember yes. But you should give it a try and test different crystals. I would do by myself actually, but only got my CPC6128 at my side - and a black cat. 

[TotO]

OK, I will see a day...