VIC IV organization memory map may need clarification

[binarycrusader]

In the "VIC IV organization and memory access basics" section, there is a bit of text that says:

mega65-user-guide/graphics.tex

Line 303 in d1ae32d

\item The screen RAM, which occupies the memory range \$0800-\$2000 (by default)

The screen RAM, which occupies the memory range $0800-$2000 (by default)

However, the graphic immediately above it says:

Screen RAM
$0800-$0FFF

Which is likely slightly confusing. As far as I can gather, the VIC-III (planned C65) used $0800-$0FFF for the "VIC screen".

Checking another C65 page, it shows this mapping instead:

$0800 2048 screen_1 ($0800-$0FCF) 2000 bytes; 
...
 $0FCF 4047 screen_2000 ;
 ; downloaded RestoreSystem, JMP/JSR_FAR routines
 ; VIC-III 80 column text screen (80x25)
C65 (911001) Memory Map - C65 mode

Addr. dec Name Comment
 $0FD0 4048 vicsprite_ptr_1 ($0FD0-$0FFF) 48 bytes; 
... ... ... ; reserved for VIC spritepointers
 $0FFF 4095 vicsprite_ptr_48 ;
 ;programmable function key definitions
 $1000 4096 pkybuf_1 ($1000-$100F) 16 bytes; 

It's unclear if the MEGA65's VIC-IV has extended that beyond the VIC-III or if this is just a typo.

[dansanderson]

Thanks, yes, it's a typo. $0800-$0FCF is correct, and notably only for 40x25 and 80x25 text modes. (There's quite a bit of other stuff in $0FD0-$2000. :) ) When wanting to use screen memory owned by the KERNAL (the "screen editor" used by PRINT etc.), I always recommend reading the start address from the VIC-IV registers, and not assuming a default.