Possible ocs/ecs chipset bug? (palette flicker) - Page 2

Toni Wilen · 01 December 2017, 17:03

ECS KILLEHB "disables" 6th plane: it is completely ignored when selecting palette. It makes no visible difference, it is only used as a genlock transparency mask.

AGA works slightly differently, it only disables EHB logic. I guess they did it this way because it is ECS compatible if palette entries 32 to 63 are copies of entries 0 to 31.

I am still wondering if there is any programs that use ECS genlock features..

ross · 01 December 2017, 17:28

Quote:

Originally Posted by Toni Wilen

I am still wondering if there is any programs that use ECS genlock features..

Maybe this is the reason they removed the feature in AGA.
No program has ever used it.

Toni Wilen · 01 December 2017, 20:13

Quote:

Originally Posted by ross

Maybe this is the reason they removed the feature in AGA.
No program has ever used it.

I did say it can be "emulated" in AGA by having identical palette in entries 0 to 31 and 32 to 64.

KILLEHB only disables EHB, it does not directly enable (or disable) any genlock features. There is separate plane selection (3 bits, ZDBSELx) in BPLCON2 that selects genlock mask plane. And finally there is bit to enable the mask (ZDBPEN).

ross · 01 December 2017, 22:34

aah, ok!

All clear now

Thanks!

ross · 02 December 2017, 14:28

This demo contain an interesting copper corrected full overscan screen h-scroll.

But could not the same effect be achieved with a sprite to mask the error on the right side of the video window?

EDIT: mmh no

the glitch is too wide.

02 December 2017, 14:28	#25
ross Defendit numerus Join Date: Mar 2017 Location: Crossing the Rubicon Age: 54 Posts: 4,491	This demo contain an interesting copper corrected full overscan screen h-scroll. But could not the same effect be achieved with a sprite to mask the error on the right side of the video window? EDIT: mmh no the glitch is too wide. Attached Thumbnails Last edited by ross; 02 December 2017 at 14:45.

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01 December 2017, 17:03	#21
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,573	ECS KILLEHB "disables" 6th plane: it is completely ignored when selecting palette. It makes no visible difference, it is only used as a genlock transparency mask. AGA works slightly differently, it only disables EHB logic. I guess they did it this way because it is ECS compatible if palette entries 32 to 63 are copies of entries 0 to 31. I am still wondering if there is any programs that use ECS genlock features..

01 December 2017, 22:34	#24
ross Defendit numerus Join Date: Mar 2017 Location: Crossing the Rubicon Age: 54 Posts: 4,491	aah, ok! All clear now Thanks!

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