Dual VIC-II's

[cts3000]

Would Dual VIC-II's be of any use in a Commodore 64? Could screen
resolution be doubled?

[Dombo]

Op 22-Apr-12 0:30, cts3000 schreef:

>
> Would Dual VIC-II's be of any use in a Commodore 64? Could screen
> resolution be doubled?

Nope.

[iAN CooG]

cts3000 <cts...@gmail.com> wrote:
> Would Dual VIC-II's be of any use in a Commodore 64? Could screen
> resolution be doubled?

AHAAHAHAHAHAHHH!!!1

--
-=[]=--- iAN CooG/HVSC & C64Intros ---=[]=-
I'm thinking of a number between one and 7000000000. Try to guess it.

[Charles Richmond]

"iAN CooG" <GETian...@OFaliceME.it.invalid> wrote in message
news:jn1k03$c74$1...@dont-email.me...
>
> [snip...] [snip...]
> [snip...]

>
> -=[]=--- iAN CooG/HVSC & C64Intros ---=[]=-
> I'm thinking of a number between one and 7000000000. Try to guess it.
>
>

Three...


--
+<><><><><><><><><><><><><><><><><><><>+
| Charles Richmond nume...@aquaporin4.com |
+<><><><><><><><><><><><><><><><><><><>+

[sjgray]

On Apr 21, 6:30 pm, cts3000 <cts3...@gmail.com> wrote:
> Would Dual VIC-II's be of any use in a Commodore 64? Could screen
> resolution be doubled?

First, technically I don't see any reason a second VIC-II couldn't be
added to the C64. Memory access would be tricky, and it would probably
require separate ram. So you could get two independent screens.
Increasing resolution (ie: combining screens) would be the hard part.
If you fed both signals into a time-base corrector and then to a video
processor it would be possible to overly one ontop the other. I
suppose if you had the hardware knowledge you could do whatever you
want by building a custom video processor to combine the signals in
any way you like. I am reminded of a special amiga monitor (can't
remember the number right now - A2024?). Basically the Amiga set up 4
"screens" and continually cycled between them and the monitor COMBINED
them into 1 screen with double the width and height. So, this
technology existed in the late 80's/early 90's... and that was before
programmable hardware FPGA's etc.

Almost anything is possible if you have the time or money...

Steve

[winston...@yahoo.com]

On Saturday, April 21, 2012 6:30:49 PM UTC-4, cts3000 wrote:
> Would Dual VIC-II's be of any use in a Commodore 64? Could screen
> resolution be doubled?

The TMS9918A had a SYNC line, and a "transparent" color that allowed you to cascade chips (or external sources) and the external video showed through the transparent areas.

But it would require its own RAM. And from all I've ever read, SYNCing didn't work very well, leading to washed-out colors or artifacts or other such issues.

So, it looked good on paper...

[commodorec...@googlemail.com]

Why not just a new, backwards compatible VIC chip with extra modes?
Well, that's more realistic, but not worth the effort.

Regards,

Shaun.

[Dombo]

Op 03-May-12 16:13, commodorec...@googlemail.com schreef:

> Why not just a new, backwards compatible VIC chip with extra modes?
> Well, that's more realistic, but not worth the effort.

If it has to be a pin compatible plug-in replacement for the VIC-II
chip, there isn't much room for radically enhancing the graphics
capabilities due to the limited amount of memory the VIC chip can
address and the limited memory bandwidth. If it doesn't have to be a pin
compatible replacement you would have to redesign everything around it
too, which essentially boils down to designing an entirely new computer
that is (hopefully) C64 compatible (which has already be done by some).

And there is the question of what would be the point of such a chip
since there is no existing software that takes advantage of the added
capabilities, and there you be very few capable and willing to write
software specifically for that chip.

[sjgray]

A "replacement" VIC could have 64K ram inside the chip itself. Writes to memory could be monitored and written into the replacement chip, therefor displaying the screen would not actually need to read C64 ram, eliminating the bandwidth problems. I think this is how the Chameleon works. With bandwidth limitations removed you could easily increase the colors or resolution, but its true that perhaps there would be no incentive to do anything with it or create new software for it.

I think a better reason for doing this would be to make a cheap replacement chip that has its own VGA or HDMI output so that the computer could be attached to newer displays. As composite/s-video monitors become obsolete there will be no way to hook up our computers any more. Also, the price of replacement machines/chips seems to be getting higher and higher all the time. People want to experience the machines and games like they remember, using real hardware. If it breaks and can't be replaced what do you do?

This is why I am an advocate for reverse engineering the custom chips and making pin-compatible replacements using current technologies. Already, its almost impossible to find replacement CPU and TED chips for the Plus/4 and C16, or CPU and TPI chips for the CBM-II series, or RRIOT chips for the old IEEE disks drives. Projects like the Visual6502 are great because this is the first step in the process.

Steve

[Brandon]

sjgray wrote on Fri, 4 May 2012 07:45:15 -0700 (PDT):

> As composite/s-video monitors become obsolete there will be no way
> to hook up our computers any more.

S-video is certainly disappearing quickly. Even high-end receivers
are less likely to have those connectors now. The last time I bought
a screen for the game room I had to look around to find one with
S-Video inputs.

But there will be video adaptors for some time to come -- it seems
unlikely that there will be "no way" to hook them up given how
prevalent composite has been. Items like this:

http://www.google.com/products/catalog?hl=en&q=s-video+to+hdmi&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1437&bih=926&um=1&ie=UTF-8&tbm=shop&cid=2823581439320539531&sa=X&ei=IyCkT9OjHcq-tweHr9iZDQ&ved=0CL8BEPMCMAE

...will likely always be much less expensive and far more versitile
than redesigned VIC chips would be to produce.

> Also, the price of replacement
> machines/chips seems to be getting higher and higher all the time.
> People want to experience the machines and games like they
> remember, using real hardware. If it breaks and can't be replaced
> what do you do?

It's already difficult given that LCD screens (especially large ones)
do not give an authentic reproduction of what you see on tubes,
especially with interpolation algorithms turning pixels into blurry
messes.

--
-Brandon
http://www.brandonstaggs.com/c64.html