Re: Porting existing stuff (was Re: VIC-20 mega expansion memory map)

From: Marko Mäkelä (
Date: 2003-01-25 08:23:25

On Fri, Jan 24, 2003 at 09:35:27PM -0500, Ethan Dicks wrote:
> Dunno.  Does that work without tricking the Kernel print routines
> (this program just emits strings to $FFD2)

You would have to handle carriage returns and scrolling yourself, but
I think it's otherwise doable.  There is a zero page based pointer array
to the beginning of each line in the screen memory (originally for handling
continuation lines).

> > On PAL, there are 35.5 visible columns (of which maybe 4 are
> > invisible on some televisions).
> 31 is still better than 23.

However, on NTSC, you only have 65 cycles per line (while PAL has 71), and
thus, at most 32.5 columns to play with.  But 28 is still more than 23.
Hmm, that was from memory.  See for more exact data.
The maximum PAL screen size is 29 columns by 35 lines = 1015 characters.
The maximum NTSC screen size is 26 columns by 29 lines = 754 characters.


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