VIDC shrunken screen modes

[garfield]

For the VIDC screen modes targeted to standrd monitor type, can these be customised (via registers) to reduce the memory footprint used? In other words, use fewer rasterlines (vert) or narrower lines (horiz) ?

I know that the Beeb's CRTC can do this, but I'm not sure about the Archimedes's VIDC capabilities around this customisation.

[SarahWalker]

Yes, screen size is fully configurable.

[garfield]

Yes, screen size is fully configurable.

Thanks Sarah.

[iomanoid]

I’ve been going through a whole bunch of old Arc demos lately, and there were definitely a few that used less than the whole screen in weird ways.

There was at least one that seemed to do total overscan too, though. I always thought (back in the day) that that was a total impossibility with the Archimedes hardware. How??

[IanJeffray]

There was at least one that seemed to do total overscan too, though. I always thought (back in the day) that that was a total impossibility with the Archimedes hardware. How??

I'd call standard RISC OS 3 screenmodes like 35/36 "overscan", but VIDC's pretty flexible in terms of its timings and capabilities so if you're willing to risk not conforming to accepted safe parameters, world's your lobster really. I remember being wowed at Tertis doing its "whole screen bounce" thing, which IIRC I copied for some game/demo or something - moves the 'whole screen' way in to the standard border area.

[paulb]

I remember being wowed at Tertis doing its "whole screen bounce" thing

What I found rather interesting was that Acorn apparently used VIDC (with some additional interface logic) for their laser printer interface podule, doing the kind of direct driving of a print engine that became more familiar when Computer Concepts released their LaserDirect cards. See pages 137-138 and 150 of...

"Acorn Technical Publishing System Technical Reference Manual"

[IanJeffray]

What I found rather interesting was that Acorn apparently used VIDC (with some additional interface logic) for their laser printer interface podule,

That's hilarious. Just using it as a DMAing 'serialiser' (albeit to 4bit) ?

[iomanoid]

I'd call standard RISC OS 3 screenmodes like 35/36 "overscan", but VIDC's pretty flexible in terms of its timings and capabilities so if you're willing to risk not conforming to accepted safe parameters, world's your lobster really. I remember being wowed at Tertis doing its "whole screen bounce" thing, which IIRC I copied for some game/demo or something - moves the 'whole screen' way in to the standard border area.

Yeah I don’t think I’ve ever had a monitor that supports those beasts I mean standard basic (15kHz?) ones. Which is all I have here now, and this took over everything. Maybe I’m just easily impressed though

Which Tetris, btw? I only know/remember the BIA one. And now I’ll have that music running through my brain the next 24 hours, cheers

[IanJeffray]

I'd call standard RISC OS 3 screenmodes like 35/36 "overscan", but VIDC's pretty flexible in terms of its timings and capabilities so if you're willing to risk not conforming to accepted safe parameters, world's your lobster really. I remember being wowed at Tertis doing its "whole screen bounce" thing, which IIRC I copied for some game/demo or something - moves the 'whole screen' way in to the standard border area.

Yeah I don’t think I’ve ever had a monitor that supports those beasts I mean standard basic (15kHz?) ones. Which is all I have here now, and this took over everything. Maybe I’m just easily impressed though

I believe those should work with any PAL standard monitor.

Which Tetris, btw? I only know/remember the BIA one. And now I’ll have that music running through my brain the next 24 hours, cheers

Tertis, not Tetris. By S.I.C.K. Here's a video of the screen-shaking effect : https://youtu.be/YYGulsgO-os?t=155

[iomanoid]

I believe those should work with any PAL standard monitor.

Even these SCART badgers? That’s cool, a new mode number or two is just what I need right now.

Tertis, not Tetris. By S.I.C.K. Here's a video of the screen-shaking effect : https://youtu.be/YYGulsgO-os?t=155

Haha - sorry, cloth gown confusion. Missed that one, looks lush, and I see what you’re saying. And Tetris videos are just so beautifully chilling