CRT for Minimig and Indivision AGA mk2

deladrevoc

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Hi All,

I’m looking at an iiyama MM904UT Vision Master Pro 455 for my Minimig and wondering if it will play nicely with my Indy AGA mk2 when it comes to games? Is it possible to achieve 100% smooth scrolling or am I hoping for too much?

specs: Horizontal: 30.0-96.0kHz, Vertical: 50-160Hz

Thanks for your help :)
 
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BLTCON0

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The supported range is fine (any in-range CRT is perfect for 100% smooth scrolling).

With the Minimig you'll get smooth scrolling.

With the Indy AGA MK2 it's a bit more complicated - from what I've read it doesn't support Vsync so you can't really expect its output to be in perfect sync with the Amiga's chipset. This will result in either a missed or gained frame every so-many seconds, visible as a momentary jump or stutter in the scrolling. But the scrolling will be perfectly smooth otherwise, in the sense that never during a single field will parts of two successive frames be mixed together.

Say the Indy outputs at a perfect 50 Hz, while the Amiga for various reasons outputs at 50.1 Hz, for simplicity suppose these don't change throughout.
This means that every second the Amiga draws 0.1 of a frame more than the Indy outputs, or 1 frame more every 10 seconds. So every 10 seconds the Indy will have to disregard 1 frame in order to stay on the same timeline with the Amiga's output. This will be perceived as a skipped frame aka a 'jump' in movement every 10 seconds. In slow-paced games it won't be noticable, in fast scrollers it will be (esp. if the screen scrolls more than 1 pixel per frame).
Similarly, if the Amiga outputs at 49.9 Hz, the Indy will have to wait for 1 frame every 10 seconds as the Amiga will have lagged behind. So the Indy will have to redraw the last frame while waiting for the Amiga to catch up. This will be perceived as a stutter in movement every 10 seconds.

This behaviour is normal when having a freely programmable scandoubler, e.g. the exact same thing happens with the Picasso IV scandoubler. Don't know if that's the case with the MK2 though or they skipped Vsync support for other reasons. The MK1 supports it.
 

deladrevoc

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Thanks for the detailed reply BLTCON0, I guess the MK1 was designed with CRT's in mind and the MK2 with their obsolescence?

I bought the monitor anyway as it was virtually given away, the Minimig was in need of something a bit more retro anyway. It's working very well and certainly gives a more authentic feeling.

Just need to find somewhere to put it now! :)
 

keropi

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VSYNC in mk2s is one of the features promised by IC and was left at that...
atm I am running my mk2 with a 50hz screenmode on my HP lcd: the lcd luckily works with 50hz and you get some bumps like BLTCON0 explains - but nothing bad that won't let you enjoy a game. Certainly beats having to sacrifice space for a crt monitor for me.
 
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