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Re: Apple IIGS info and stuff
In article supertimer@aol.com (Supertimer) writes...
>"Myconid" <myconid@hotmail.com> wrote:
>>Can someone tell me how advanced a IIgs realy is? Can they take modems and
>>hard drives and sound cards? Mine had a built in speaker..
>
>The IIgs is a classic today. I'll say it so that Mitchell does not have to
>(again)....it won't compare to a Pentium or PowerMac. There, I said it.
Trying to vilify me for being a realist? :) You might as well
throw in it doesn't compare to a 486 or even most 386's. As for a
couple of the early PowerMac's, I thought it compared quite well
equipped with an accelerator (the Finder seemed sluggish on the
6100/60 PPMac's I used back in 1995, compared with my GS Finder).
Not that the 65C816 is more powerful than any 601 PowerPC chip
obviously, but I found that kind of amusing back then. ;)
This probably has no logic in it, maybe because its all based on
sentiment, though my Pentium (as well as any Mac's I've used) lack
any of the magic the GS has. There's just something about the IIgs
which makes it seem special, though I can't quite put my finger on
it. Apparently I'm not the only one who feels this way from people
I've spoken with. Maybe it was the jump from an 8-bit Apple II to
the IIgs? Hard to say, but it still remains my favorite computer.
>Here are the vital facts about the IIGS....
>5. CPU:
> Western Design Center (not to be confused with Western
> Digital, the hard drive maker) 65C816 running at 2.8Mhz.
To nit pick here, when used in the IIgs the processor ran
at around 2.6 MHz due to RAM refreshes. The only circumstance
where it ran at a full 2.8 MHz was when accessing ROM firmware.
(It makes a noticable difference on the ROM 3, where Quickdraw
toolsets are fetched from ROM rather than RAM).
> Speed can be increased to 15Mhz with an add-on CPU card.
Actually you can go up to 16 MHz, that is the maximum
speed you can attain with current accelerator cards. Due
to the GS's fixed 1 MHz bus speed though, its performance
really hits a bottleneck at around 10-12 MHz.
>6. ROM:
> 256K in the 1989 "ROM 3" model (Apple skipped ROM 2
> so as not to confuse "Apple II" with "ROM 2")
Not at all. The "ROM 2" was skipped to avoid confusion
with all the printed references made in technical documents
referring to the ROM 01 as the "2nd ROM" (which is was, as
there was one ROM revision before it).
Starting with the Apple IIgs with 1 megabyte, Apple
decided to start labeling the GS's firmware in the order
in which in was released. So as the third ROM revision,
the next firmware version was simply called "ROM 3". If
more IIgs or firmware updates had been produced, there
would have been the "ROM 4", "ROM 5", "ROM 6" and so on.
> ROM is expandable to 8MB (some cards use ROM
I thought the Apple IIgs could expand its ROM to a
maximum of 1 MB. This is what is printed in techincal
references at any rate.
>7. RAM:
> The Apple IIGS is expandable to 8MB of RAM
> with the right memory card.
True, however the IIgs will only support DMA to the first
4 MB plugged into the expansion slot (this applies to all GS
revisions--the ROM 00, 01 and 3).
> Both Alltech
> Electronic (www.allelec.com) and Sequential Systems
> (www.sequential.com) are selling 8MB memory cards as
> of April 1988.
I assume that was a typo. :) There were no 8 MB cards being
sold in 1988, aside from MDIdeas' OctoRAM card.
>10. Display:
> --640x200 with 4 pure colors: this mode is bland
> and is not often used.
Actually it is the same mode as below, only the same four
colors are copied and repeated in each of the 4 mini-palettes
so you end up with four pure colors.
> --640x200 with 16 dithered colors: in this mode, the
> pixels in the graphic screen are grouped into
> even and odd columns. The even columns can have a
> palette of 4 pure colors out of a of 4096 possible.
> The odd columns can have a second palette of 4
> pure colors. The GS dithers the adjacent colors
> for 4x4=16 dithered colors. This mode is widely
> used in productivity programs and also in Apple's
> Finder for the GS.
White and black get repeated in each of the 4 mini-palettes,
so you have them in both the odd and even pixel columns. That is
why you have readable text in the 640 mode (it'd be difficult to
read if text were dithered). So there are 6 pure colors usually
present in the 640 mode, of which only 2 remain pure (black and
white)--the other 4 get mixed to make the 16 dithered colors.
Using dithering in this mode is kind of retro in that it
artificially recreates the color placement restrictions that
were present in old 8-bit Apple II. You often end up halfing
the resolution and create color fringing too (all in all, it
can be an ugly mode).
> --Fill mode: for faster rendering of graphics, the
> fill mode is a hardware mode in which an outline
> of a graphic can be drawn and the outline filled
> by a solid color without needing to draw in all the
> pixels.
There are limitations. You only have 15 colors available
in this mode per-line and there is only one start and one stop
pixel to mark the area to be filled. For this reason, you cannot
have fill mode objects overlap each other, which is what is
a key element in writing games with sprites.
> SVGA modes with 24-bit color can be added with an additional
> video card (see the Second Sight SVGA card at Sequential
> Systems http://www.sequential.com/ ).
No comment. ;)
> The Apple IIGS also has all the graphics modes found on
> the Apple IIc.
> --Text mode: 40x24 and 80x24. Characters are formed
> by a 7x8 pixel matrix. Text mode is monochrome but
> can be set to a specific color. The background
> and boarder can each be set to different colors.
> Text mode is rarely used in GS programs since the
> OS, GS/OS, has a graphic desktop.
Using scanline interrupts, you can do neat tricks like having
the foreground, background and border color changed on a line by
line basis (much like the 256 color mode, only you have multi-
colored ASCII text in this case).
> --High Resolution: 280x192 pixels in 6 colors
That resolution is only producable in monochrome mode. When you
add color, it is effectively reduced to 140x192.
> --Double High Resolution: 560x192 pixels in 16 colors.
Same as above, when color is added it is reduced to 140x192.
> --Combinations/Variations: 4 lines of text mode can
> be mixed with a truncated Low Resolution or High
> Resolution mode graphic. The text in mixed mode can
> be either 40 column or 80 column. Double Low Res
> and Double High Res modes can't be mixed with text.
Nope, you _can_ mix 80 columns text with graphics in the
Double-High-Res mode and possibly in Double-Low-Res as well.
> The difference between a UniDisk and a IIGS 3.5" drive
> is that the IIGS drive is controlled directly by the
> computer while the UniDisk has a separate processor.
> The UniDisk is thus much slower (up to 4x slower) than
> a IIGS 3.5" drive.
The UniDisk 3.5 is actually closer to half the speed of
of an Apple 3.5 drive.
> The Apple IIGS often shipped with the Apple High Speed
> (DMA) SCSI controller in an expansion slot for
> controlling SCSI devices. Even 100MB Zip Drives and
> 1GB Jazz Drives work on this SCSI port.
Hmm? I don't recall Apple ever pre-installing SCSI boards
inside the unit at shipping time. They did at one time install
Apple IIgs Memory Expansion Cards as standard, which meant GS
machines shipped with 512K for a period.
> In one final gasp, the Apple II supporters at Apple
> designed the Apple IIGS Plus, code named "Mark Twain."
> It had an 8Mhz 65C816, a built in SuperDrive, 2MB
> on the motherboard, and a hard drive. Prototypes
Where did you come up with an 8 MHz 65C816? All the Mark
Twain prototypes that have been discovered have the same 40
pin DIP 65C816 running at 2.6 MHz as other GSes. It is quite
plausible a faster processor would have been added to the
final production model, just as better graphics probably
would have been later added.
Mitchell Spector
spec@vax2.concordia.ca