[Coco] There was a CoCo 3 update to Zaxxon! Before Z-89

[Andrew]

On 3/20/24 10:18 PM, coco-request at maltedmedia.com wrote:
> Message: 6
> Date: Wed, 20 Mar 2024 15:18:06 -0500
> From: Allen Huffman <alsplace at pobox.com>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Cc: Andrew <keeper63 at cox.net>
> Subject: Re: [Coco] There was a CoCo 3 update to Zaxxon! Before Z-89
> Message-ID: <B435A623-7F1A-4092-8E00-A3776E86604B at pobox.com>
> Content-Type: text/plain; charset=utf-8
> > It dawned on me that this could have been a way to make 1983 Zaxxon> 
display in color on the CM-8 monitor, similar to games using the
> PMODE4 screen would patch to use PMODE3 and weird colors. The CoCo 
> 3 would let you remap the colors used in PMODE4, so it could have 
> matched the black/white/red/blue used in the game.

This is what I was thinking, too; I think I recall seeing how to do that 
back "in the day" when I was a kid, but I don't know if I ever played 
with it at all back then. Probably not, as I was pretty enamored with 
the CoCo 3's 16 color mode...

> But I think Roger saw ?256x192 16 colors? on the disk label, and 
> there is a sprite editor Bjork used that shows the spaceship (four 
> versions ? large to small representing different flying heights) 
> clearly showing a palette of 16, though only four colors being used 
> by the ship.

Where was this detailed? Discord or some other "back channel" (just 
calling it that because I'm usually looking here or the FB group, and 
only rarely on Discord; beyond that, not much else unless I randomly 
find something during Google searches along the way; there's a ton I miss)?

> If it truly is using a 16-color screen (4 bits per pixel) then all 
> the graphics would have had to be converted, PLUS it would then be 
> moving twice as much data. The speed it runs makes me think maybe 
> it?s just using a PMODE 4 screen (?) with pallet adjusted.

It's been forever since I last played Zaxxon on the CoCo - but I do 
recall it being "PMODE 4" - did it really run that fast? Actually, now 
that I think about it...and please correct me if I'm wrong:

I don't know why I didn't think of this - but "PMODE 4" is the artifact 
color screen; it only has two "true" colors - black and "white" (called 
"buff", something very close to white, as I recall?). On a B/W composite 
monitor or TV, you just see the alternating vertical lines that make up 
the "colors".

So - would changing the palette of the "buff" channel (the only one you 
could alter, I think, as you can't get the "color" black any other way?) 
allow the alteration of the "red/blue" (or whatever those artifact 
colors are named - "red/blue -ish")? I wouldn't think it would work that 
way, as the point of how artifact colors work is that you're "slamming" 
the raster dot between "extremes" of black and white, and the bandwidth 
of the NTSC system is exceeded and "bleed-over" colors occur (or 
something like that - a very layman, probably incorrect understanding of 
mine; analog electronics beyond the basics has always been "magic" to me 
- I'm certainly no Bob Pease!)...

If that understanding of mine is correct, then wouldn't you -need- to be 
in "PMODE 3" to get the actual 4-colors (palette regs) to be able to 
alter them? Or does the GIME (internally) "emulate" the 6847 when in RGB 
mode and... (ok, that line of thought just seems outlandish, so I'm not 
finishing that)

Sigh...well, none of this is here nor there; I dunno. But one other 
"last thought": Was there a 256x192 mode in the GIME that allowed for 4 
or 16 colors? Not something accessible from BASIC directly, but one of 
those "hidden" modes if the registers are set properly (like the 
160x192x16 color more - I think that's in there)? Or maybe a 320x192x4 
color mode (can't recall if that was "HSCREEN 1" or "3" without looking 
it up)?

There are a lot of these things I look on today and wonder "why the heck 
didn't I appreciate those modes more back when I was a kid", along with 
the whole "why the heck didn't I play with the artifacting in the 
high-res 640x192 2 and 4-color modes"; a couple of questions I lightly 
kick my butt over every now and again (I was just a very dumb and lazy 
kid - now I'm just a dumb and lazy "old man")...heh. :)

> What is significant about 1992?

The only reason I mentioned that year, was that it was the best I could 
come up with for "transition of the CoCo to EOL" kind of "status"; a 
very artificial line, I suppose, but to me at the time it was a kind of 
personal turning point:

I got my first programming position in January of that year, and I 
graduated from the votech school I went to here in Phoenix.

I also got my first Amiga (2000), later that year; we had used the Amiga 
500 for certain things during my schooling, and I also recall the 
amazement I had prior in high school seeing an Amiga for the first time. 
It was kinda imprinted on my brain as the "next machine" I wanted (and 
the first I had selected and purchased on my own).

The computer I had prior to that, but after my CoCo's, was a Tandy 
1400HD; my first PC was also my first laptop. My parents had wanted me 
to have something to do work on for school when I left home (also 
interestingly to me, I used the parallel port of that laptop to play 
around with external control of my own custom electronics using a 
computer - something we learned about in the school, too, using IBM PS/2 
machines with a custom assembled ISA card that had an 8255 PPI on it).

At some point, I need to dig that old laptop out, look it over, and see 
about getting it up-and-running again. I have way too many old machines 
laying around (I still have the Amiga 2000, too - and my Amiga 
1200...and my first 486...and my first...etc)

Ok - I'm leaving things here; but I did read the remainder of your reply 
- my response is already becoming yet another chapter for my book... :D

Take care!

Andrew L. Ayers
Glendale, Arizona
phoenixgarage.org
github.com/andrew-ayers