Re: Second Sight Features

[bazyar@netcom.com (Jawaid Bazyar)]

spector@vax2.concordia.ca (Mitchell Spector) writes:

>	What of the 320 and 640 multipalette modes? 


  No problem. 16 palettes x 16 colors each = 256 colors. :)

>Does the current on board 
>firmware support shadowing of 320x200x256, 320x200x3200 and 640x200x128+? 

  Yes, no, yes. No 3200 because there's no way you could sync up the
SS's VBL to the Apple's.

>(The
>latter is rarely used, although some popular applications like System 6's 
>synthLAB make use of it). I'm also curious how 640 mode dithering will appear 
>on a VGA/SVGA screen, won't colors look less solid (horizontally) because of 
>the higher resolution and dot-pitch?

  Correct. In general it doesn't look too bad.

>	I'm also concerned with current (what is it now?) FPS rate and 320 
>mode "blocky" looking pixels when shadowed to a VGA/SVGA screen. 

  Oh hell, they're not _that_ blocky :)

  As to the FPS rate, the board can do 15 full-screen updates per second.
However, it rarely has to do a full-screen update, since the card
knows which of either screen regions have been modified and only
updates what it needs to. In general use you can't tell there's
a Z180 in the video loop.

  Some intensive programs (like Demos, Rastan perhaps) will act a bit
sluggish. Arkanoid, for example, plays great.

>For this
>reason, can you disable the Second Sight and get the old standard video
>output on an AppleColor RGB monitor? (No emulation of older graphic modes
>on my 12" screen, all video singals generated from VGC on motherboard as
>if the Second Sight wasn't plugged in). I just want to be sure I won't
>have to pull the card out just to see text and graphics as they appear
>_now_ on my system. :)

  Switch-box. :)

>>The card is capable of the following SVGA video modes:
>> 
>>  Text
>>
>>	132x25
>>
>>(* indicates that the mode is not available when used with an AppleColor RGB
>> monitor.)

>	I assume you forgot the asterix by the 132x25 Text mode, unless you
>found some neat trick of getting that displayed on an AppleColor RGB. ;-)

  No, I did _not_ forget the asterisk. The AppleColor RGB monitor is capable
of readable 132 column text - which means that 1024x400 graphics modes
are possible too.

>	No JPEG support? And only 8-bit TIFF conversation? I hope
>HiColor (32k) and TrueColor (16M) support will be added to the 
>viewer in the near future. 

  Yep, just haven't had time. JPEG needs to be done right. :)

>Does this mean there are two separate versions of the card, one with all
>memory factory installed, and another with 4 empty DRAM sockets?

  Yep.

>	For those of use sticking with our AppleColor RGB screens (until we
>can afford something better :), would 1MB be required to get a 640x400x16.7M
>display or will 512k handle that? And what is the maximum number of colors
>that can be displayed at 320x200 and 640x200?  

  A IIgs requires 1MB VRAM, as mentioned above. You can display 16.7M
colors at any resolution less than 640x480.

>Hmmm, I've heard of an adapter that allows PC users
>to connect Macintosh RGB screens to their IBM PCs -- would such an adapter
>work with the Second Sight card? 

  Ought to. VGA is VGA.

>	Will scanlines disappear when using a Second Sight with the standard
>AppleColor RGB screen? 

  Unfortunately no. The VGA controller can't do both scanline-doubling
and interlace at the same time for some strange reason.

>Losing the scanlines is nice, but chunky pixels and a reduced frame-rate 
>might not be). 

  As I said, pixels aren't _that_ chunky on a VGA monitor.

> I think using a Second Sight with the old AppleColor RGB
>makes about as much sense as using the card on an Apple IIe; it'll work,
>but your limiting the potential/power of the card. Probably the reason you 
>don't see much focus on the Apple RGB or IIe when it comes to Q&A on the 
>card. :)

  Well, it _is_ a VGA card after all. :-)

>	What would happen if a programmer (either stupid or evil) overrides
>the firmware and forces higher resolution modes than the AppleColor RGB can
>handle? Will it blow up in our face? :) I guess this would only be a problem
>if a virus were written, but in a community this small, I doubt we'd have to
>worry about it.

  The AppleColor RGB seems to be a quality-designed monitor. I have
fed it some pretty nasty video signals and in a couple cases it shut
itself off, but cycling power after letting it sit for a few seconds
it came back to life.  Some VGA monitors will blow their circuit boards
if you feed them video signals they don't like (I've done this before).
Multisyncs obviously don't have this problem. :)
-- 
 Jawaid Bazyar              |   Like UNIX? Like your Apple IIGS? Then ask
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