Re: US VIC-20 & interlaced graphics

From: Marko Mäkelä (
Date: 1998-10-28 19:21:08

On Wed, 28 Oct 1998, Mark wrote:

> (But will the timing be off due to the 9VAC being at 50Hz instead of
> 60Hz?) 

The VIC-20 doesn't use AC power for anything else than the user port's 9
VAC output.  The original (not CR=cost reduced) VIC-20 even works with DC
voltage (12 volts, a bit over one ampere; maybe it worked also with 6
volts) fed to its two-prong connector.

> A while ago someone said that the NTSC (not PAL) VIC-20 can do true
> interlaced graphics

True, get my simple interlace demo (it shows an interlaced text screen) 

> Anyway, I'm wondering whether there are any VIC-20 programs or demos
> that make use of this to give nearly 400 lines of vertical resolution? 

I'm not aware of any serious demos that make use of it.  Get my demo
routine and extend it as you wish.  I just wanted to show that it is

> (Actually, pressing one of the function keys in Radar Rat Race* may*
> have turned interlace mode on, but since the same thing is displayed in
> both odd and even fields so there is no increase in vertical
> resolution.) 

It could switch the character set between the fields to achieve true
interlacing.  But Vic Rat Race (originally Vic Car Race) has very poor
graphics anyway: the screen is updated in a "PC-like" manner, everything
will flicker wildly, because the program doesn't care about the raster
beam's position. 


P.S.: I've almost finished my Thesis text now.  Anyone who would like to
have an updated copy for review, should contact me before Saturday.

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