Re: MAME For IIGS?

[spec@vax2.concordia.ca (Mitchell Spector)]

In article joeschmoe@nospam.org (Joe Seeley) writes...

>In article spec@vax2.concordia.ca (Mitchell Spector) wrote:
>
>>SPEED:
>>-----
>>
>>    Emulation through software requires extensive CPU power and raw
>>speed, which unfortunately, the IIgs has very little of. The stock
>
>I thought a lot of the arcade games (Gauntlet and the Mr. Do series comes to
>mind) actually used the 6502.  Since the 65816 already has this emulator 
>built in I thought that would be a help.  Also, I didn't realize the 
>limitations of the accelators.

    Yes, several games did -- and in theory you could use the 65C816
to run 6502 code and instructions without having to emulate the chip.
The only problem is there are MORE things being emulated than simply
a processor. If it were that simple, someone would have written a
software based Apple II emulator for the Apple IIgs (Why do this
when there is hardware emulation already built-in? Well being able
to run ProTERM, AppleWorks or Ultima in a Finder window would be neat).

>>to 4 or 16 colors without limitations. You can play with multiple
>>palettes for up to 256 colors in the 320 mode, but many games used
>
>This did occur to me after posting the original.  However, I think most of 
>the games MAME emulates could be handled by the above mentioned 320, 256 
>color mode, no?  I thought only a few (Rampage, Popeye and Spyhunter) use 
>higher resolutions.

    Actually, no. 320x200 is not a suitable enough resolution. Take for
example an old arcade game like Ms.Pac-Man, that used a resolution of
224x288 (in the original game they flipped the CRT on its side inside
of the cabinet). You would have to program it so the GS recreates the
image 90 degrees rotated and then _physically_ lift up your monitor
and place it on its side so the image is upright. Even still -- you
would be 24 pixels short and the bottom of the display would be cut.
I wouldn't even consider the 640x200 mode since there are far too
few colors available (and dithering makes an awful mess). On MAME PC,
I often run most games in 800x600 mode with scanline emulated, though
some games fit fine in 640x480.

    As for color, 256 colors requires a trick where you change the
palette on different scanlines. You still have only 16 colors per
each scanline (16 scanlines * 16 colors = 256 colors). A number of
games used more than 16 colors going horizontally across, although
this is trivial compared with the resolution and speed problem.

>Graphics speed is what would blow though.  Thexder was a good
>example of what could be done although it was all native.

    For its time it was, but looking at it today it has a pretty
slow and choppy frame rate (although running it at 15 MHz really
fixes that I must admit). If you look back, many of the classic
IIgs games like Marble Madness, Zany Golf, The Immortal, Rastan
and Task Force were not full-screen -- they used small display
windows in order to achieve any kind of decent frame rate (and
often still were not perfectly smooth of you look closely at the
scrolling backgrounds).

    The Apple IIgs has always been terribly crippled in terms of
speed, especially since there was no blitter or sprite chips to
help move graphics along. Programmers had to make huge efforts 
(and utilitize several tricks) in order to get graphics moving 
nicely; many just eventually gave up when Apple refused to supply 
the GS with a faster built-in processor. 

>BTW, for those who are interested, telnet to: frank.searchlight.com
>
>It is most likely the only telnettable BBS that is run on a TRS-80!  Again, 
>if a Model III TRS-80 can be doing this, it certainly isn't the limitations 
>of the IIGS that is stopping new and innovative software from gushing forth.

    There are at least two Apple IIgs BBSes you can telnet to. I don't
recall what the addresses are, but I believe the sysops frequent this
newsgroup still.

>>in my Apple IIgs (and other II's) and new software is what is will
>>ultimately keep my interest level up. comp.sys.apple2 is my link to
>>the II world, but with not much happening except fighting and other
>>noise, my interest is starting to dwindle (seeing the remaining users
>>and developers do nothing but fight and talk about other things does
>>little to spark anyone's interest I'd imagine).
>
>Amen again.  Even if one could get TCP/IP and a decent browser going (as well
>as figure out a way to break the 14.4 barrier) it would extend the longevity
>of the IIGS for many years.

    TCP/IP has already been written for the Apple IIgs, there are two
separate projects in the works. You can download the beta version of the 
one called Marinetti right now, but it only supports SLIP and so far, the
only available application for it is a telnet client. The closest thing
to a web-browser right now is Spectrum Internet Suite (an add-on script
for the only GS/OS telcommunications package). I think it is overhyped
though, since it requires a shell-account and works as an enhancement
for Lynx basically (it's a text only browser).

    14.4 barrier? There never was any, unless your talking about using
a stock Apple IIgs with a modem and no accelerator. I've used a 33.6K
modem just fine on my own Apple IIgs, no problems at all. There is
little motivation to connect up more than a 14.4K modem however, at
least until PPP and several Internet applications are written and
you can split the bandwidth.

Mitchell Spector
spec@vax2.concordia.ca