NTSC/PAL combo A500 -- How did they do it?

[orb85750]

NTSC/PAL combo A500 -- How did they do it?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250907589372

[ChaosLord]

ALL A500s built after 1988 are PAL and NTSC.

And all A500s built in 1987 and 1988 can be easily upgraded to be both PAL and NTSC.

Ditto for A2000.

[Matt_H]

The 1MB Agnus chip can handle both NTSC and PAL. It's easier to switch it in software, but you can wire up a hardare switch, too, as this seller has done.

[orb85750]

Even with WB1.3?  How do you do it with software?

[amiman99]

The 1MB Agnus chip can handle both NTSC and PAL. It's easier to switch it in software, but you can wire up a hardare switch, too, as this seller has done.

I did that on A2000 and A3000.
A2000 there is a trace jumper you can cut and wire a switch, on A3000 there is a jumper, which I fitted with a switch, both work great.

[freqmax]

How to switch in software if the computer starts in the wrong mode?, hard to see any GUI

[alexh]

If you have Kickstart 3.1 (40.63) then it's hold down both mouse buttons during reset and then press space. Don't need a GUI

[Kronos]

1.3 didn't have a option for switching NTSC/PAL, but since it's really just one bit it's not too hard to do.

Back in the days a typed in a short assembler-listing found in a magazine and put the resulting exe on a bootable floppy.

After booting the A500 would auto-reset (you now had to remove the floppy pretty fast please) and returned in NTSC mode. Pretty nice for WB (couldn't stand 50Hz) or games that didn't use the extra screen real estate offered by PAL.

Note, a PAL-Amiga switched to NTSC is still producing PAL only at 60Hz instead of 50Hz and vice versa.

[psxphill]

Note, a PAL-Amiga switched to NTSC is still producing PAL only at 60Hz instead of 50Hz and vice versa.

That is not really relevant for a500/a2000 as they only have mono composite out anyway. So they are neither PAL or NTSC (neither are the RGB ports on any of the Amigas).
 
It was common to use NTSC to mean 60hz and PAL to mean 50hz (even AmigaOS does it). The official name of EIA 525/60 & CCIR 625/50 are not as catchy & haven't caught on.
 
Adding a 1mb agnus and a toggle switch is probably the easiest way if you want 1.3 compatibility. However if your monitor can't show both 50 & 60hz then you might as well just hard wire it. Or even just get the correct agnus for your region. The earlier agnus had a seperate 50 & 60hz part, which are often referred to erroneously as NTSC & PAL.

[spaceman88]

NTSC/PAL combo A500 -- How did they do it?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250907589372

As long as it has the 1 Meg Agnus you can hook up a switch or most people just used a disk called "PALbooter". You put the disk in and 500 would reboot, then you would put in your game that would only run in PAL. When you were done with the game, reboot again and your back to NTSC.

[Matt_H]

Degrader should work under 1.3

[freqmax]

How did PAL machines produce a proper clock for NTSC? the existing isn't evenly divisable..

[Zac67]

They don't. For exact compatibility (genlock, A2024 monitor) you need to swap the oscillator - usually this isn't necessary though.

[Kronos]

They don't. For exact compatibility (genlock, A2024 monitor) you need to swap the oscillator - usually this isn't necessary though.

A2024 works just fine on a PAL Amiga, no matter wether running 50 or 60 Hz

[Zac67]

A2024 works just fine on a PAL Amiga, no matter wether running 50 or 60 Hz

A PAL 2024 works fine on a PAL Amiga.
A friend of mine had an early A1k that had been converted from NTSC to PAL (Agnus switch) and had been used for years. Then he bought a 2024 and that wouldn't work (strange video artifacts). I swapped the oscillator as well and that did the trick.
50 or 60 Hz doesn't matter with the 2024 but the pixel clock does matter.