Re: Guru Meditation Exact Visual Specs

Date: Thu, 11 Aug 2016 22:16:15 +0200
Message-Id: <>
> On 2016-08-11, at 16:04, smf <> wrote:
> On 11/08/2016 12:42, Christian Euler wrote:
>> The frame timing relies on the vertical blank counter by using graphics.library/WaitTOF(). This means that the blinking speed is different on a PAL or NTSC machine.
>> Alerts are displayed on a default PAL (or NTSC) 2-colour hires screen mode.
> OCS chips couldn't switch between PAL and NTSC anyway, you were stuck with the default.

Which was?

> Kickstart 1.3 didn't have code to switch between them either, although you could poke the registers to switch between them if you had ECS Agnus and Denise fitted.

I think Agnus was responsible for the clocks / timings. I think I recall that the "poke" went to Agnus. And Denise improvement was that ECS was capable of processing higher pixel clock but it resulted only in the "Super Hires" mode becoming available.

> The pixel aspect ratio wasn't square and NTSC & PAL are different anyway, while modern displays and printers generally have square pixels. So you will need to adjust for that.

They couldn't be square in the non-interlaced modes (unless we exclude the scanlines' gaps from counting) but in the interlaced mode I recall I used to adjust my display so that they were close to square.


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Received on 2016-08-11 21:00:56

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