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Posted By

MIRKOSOFT
on 2017-08-25
18:12:59
 Is possible to create PAL/NTSC TED software switch?

Hi!

I'm 128'er.
VDC chip in Commodore 128 is possible to switch to PAL or NTSC by simple software switch by these commands:
Set to NTSC
SYS DEC("CDCC"),32,4:SYS DEC("CDCC"),29,7:SYS DEC("CDCC"),126,0
Set to PAL
SYS DEC("CDCC"),38,4:SYS DEC("CDCC"),32,7:SYS DEC("CDCC"),127,0

I own MiST and using C16 core - TED is set to NTSC.
Is anything similar possible to do with TED?

Miro

Posted By

gerliczer
on 2017-08-26
12:43:16
 Re: Is possible to create PAL/NTSC TED software switch?

Ask the C16 core developer. The original hardware doesn't support this. Oh, and that trickery most probably has nothing to do with NTSC and PAL. Those concepts cannot be applied to VDC.

Edit: Corrected a typo.

Posted By

siz
on 2017-08-26
05:24:05
 Re: Is possible to create PAL/NTSC TED software switch?

On a real C16 or plus/4 you can switch TED between PAL and NTSC but that only affects the clock divisor for PHI0 and the screen generation (toggle number of raster lines). But on the real hardware the base input clock is different on PAL and NTSC computers, you have to replace the crystal too if you want to convert a PAL computer to NTSC or vice versa.
Perhaps it's easier with a reconfigurable computer but you I'm pretty sure that there is no new hardware register implemented to do the base clock switching. But - as gerliczer already said - you have to ask the C16 core developer.

Posted By

MIRKOSOFT
on 2017-08-26
14:04:32
 Re: Is possible to create PAL/NTSC TED software switch?

Yes, it is also for VDC only screen generation and 50/60 Hz switch.
This exactly I want. Nice is that TED allows it, VIC-II and VIC-IIe allows even this not.

So, how to do it in TED case?

Miro

Posted By

gerliczer
on 2017-08-26
15:00:03
 Re: Is possible to create PAL/NTSC TED software switch?

What part of it is so hard to understand? Although TED has a control bit, which you can find in the manuals, but that's not enough to switch between NTSC and PAL. For real machines, you have to replace the quartz oscillator and the KERNAL ROM on the PCB. That's what the author of the C16 core for MiST has to do in the FPGA bitstream, too.

Posted By

TLC
on 2017-09-10
09:26:56
 Re: Is possible to create PAL/NTSC TED software switch?

You'll need to decide if you want the video standard to be switched "on the fly" or statically.

Either way, you need clocks for both PAL and NTSC modes.

For a static switch, it's O.K. if you hack a second crystal + trimmer capacitor somewhere around the original one, and use a switch to select either of them. Note that 1.) it won't be possible to switch clocks on the fly, since the crystals need some time to start oscillating and stabilize (...inbetween, there'd be no clock), which typically crashes the machine. And 2.) the machine will boot up from the original Kernal ROM regardless to the setting of the switch. To fix that, you probably also need to hack in a 27256 eprom or some flash with both a PAL and NTSC rom images, and select the active Kernal image according to the PAL/NTSC switch.

For an on-the-fly hack you probably need a pair of oscillator modules at the first place (so that you have both clocks available all the time, without transients), and figure out how to make the machine toggle $ff07 bit 6 (the TED PAL/NTSC bit) upon toggling the switch. But this all looks reasonably more difficult.



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