Denial

what if I do racing the beam and set $9001 later so it compares more often to $9004? As I wrote: you can't restart [the display window] after it ended by writing a corresponding higher value into $9001 ... I was always wondering how 4mat did stuff (like in C64 terms) FLD like tricks in his VIC20 in...

Many of the new graphics modes pioneered by tokra and me routinely use the entire ZP, stack and OS workspace (i.e. $0000..$03FF) for graphics data. The only thing that necessitates the use of ZP are the two indirect-ZP address modes, and maybe the odd cycle saved with ZP (instead of ABS) operands. P...

No. The display window is only triggered once per frame (when $9004 compares equal to $9001), i.e. you can't restart it after it ended by writing a corresponding higher value into $9001. What you *can* do is filling part of the display window with characters in multicolour that use %01010101 (85 dec...

Especially unexpanded for extra charm. What's the point of advocating the use of an essential non-standard hardware extension and at the same time 'disallowing' the use of RAM expansions? No - it wouldn't add any 'extra charm' to me. It just places an unnecessary restriction on any related endeavou...

$2A $52 $FB - $FE I wouldn't be that sure about $2A and $52. Even though there are no direct ZP operand fields of instructions in the BASIC interpreter that point to these two addresses, these two addresses are part of temporary float values (actually their 5th byte) and might be referenced by indi...

heaven6502 wrote:what are the ZPs which are really free?

Just $FB..$FE, actually.

...

You find more details in this post of mine.

You probably mean this one: 10-Bit Oscillator Frequency Resolution

@JonBrawn: PM sent

MrSterlingBS wrote:the Demo [...]

... uses overlapping sprites to render filled vectors on the C64 which is a method that does not transfer at all to the VIC-20 (again, that method is nothing spectacularly new. The demo "Snapshot" already did so in 2010, see the part at 7:14).

http://www.quiss.org/boo/ "BRR" is nothing new and effectively is an 8-bit 'randomized' DDA . It is illusory to assume a line routine plots ~200000 pixels/second just because the 'deciding' part within it executes in 5 cycles. This is completely ignoring the other necessary parts of the r...

Transferring all these files from *.tap to *.d64 is only doing half the job. The tape original very likely assumes (and can rightfully do so!) it was run from tape, and issues further load commands from tape. You would at least need to identify those code sections that load the next files and adapt ...

When this can't be done by just LOAD from tape and SAVE to disk (within VICE, for example), this more or less amounts to do a full crack. Even when there's no fast loader involved, the game can feature an autostart, binary non-BASIC program data (like machine code, character sets or level data) and ...

And I start the program with setting the pointers after chaining. The values in addresses 174 and 175 are only valid immediately after LOAD ! If you in-between edit the program and re-start it, indiscriminate copying of 174/175 to 45/46 will reference the old values, possibly truncating the program...

MrSterlingBS wrote:00,00 to 99,99 5516 per pixel 39

That should be 55 cycles/pixel.

You are improperly using the Euclidian distance here to pretend the line was 141 pixels long. The rasterization of lines with Bresenham plots max(dx,dy)+1 pixels, which is also 100 in the diagonal test case.

I did not know much about VIC-20 hardware during the time I had one, but on my Radio Shack Color Computer I am aware that there were certain I/O registers that were ghosted, [...] ... or mirrored ... [...] and would appear in multiple places. Is something like this happening here? Not here, in a ce...