Warning by viznut/pwp, for example.heaven6502 wrote:And which demo[s] use that bus trick?
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- Mon Feb 19, 2024 10:53 am
- Forum: Programming
- Topic: Can the display window be re-triggered? (was: 9001 when read?)
- Replies: 8
- Views: 1803
Re: Can the display window be re-triggered? (was: 9001 when read?)
- Mon Feb 19, 2024 5:51 am
- Forum: Programming
- Topic: Can the display window be re-triggered? (was: 9001 when read?)
- Replies: 8
- Views: 1803
Re: Can the display window be re-triggered? (was: 9001 when read?)
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...
- Sun Feb 18, 2024 4:28 pm
- Forum: Programming
- Topic: "Free ZP" which ones?
- Replies: 6
- Views: 1398
Re: "Free ZP" which ones?
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...
- Sun Feb 18, 2024 3:47 pm
- Forum: Programming
- Topic: Can the display window be re-triggered? (was: 9001 when read?)
- Replies: 8
- Views: 1803
Re: Can the display window be re-triggered? (was: 9001 when read?)
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...
- Sun Feb 18, 2024 3:56 am
- Forum: Games
- Topic: Multiplayer VIC20 Games
- Replies: 6
- Views: 1781
Re: Multiplayer VIC20 Games
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...
- Sun Feb 18, 2024 3:44 am
- Forum: Programming
- Topic: "Free ZP" which ones?
- Replies: 6
- Views: 1398
Re: "Free ZP" which ones?
$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...
- Sun Feb 18, 2024 3:33 am
- Forum: Programming
- Topic: "Free ZP" which ones?
- Replies: 6
- Views: 1398
Re: "Free ZP" which ones?
Just $FB..$FE, actually.heaven6502 wrote:what are the ZPs which are really free?
...
You find more details in this post of mine.
- Thu Feb 15, 2024 1:41 pm
- Forum: Programming
- Topic: Playing better notes
- Replies: 1
- Views: 1256
Re: Playing better notes
You probably mean this one: 10-Bit Oscillator Frequency Resolution
- Wed Feb 14, 2024 10:15 am
- Forum: Hardware and Tech
- Topic: Powering a C64 (or VIC-20) with a USB Power Bank
- Replies: 8
- Views: 4923
Re: Powering a C64 (or VIC-20) with a USB Power Bank
@JonBrawn: PM sent
- Tue Feb 13, 2024 4:15 pm
- Forum: Programming
- Topic: Line drawing algorithm
- Replies: 20
- Views: 4472
Re: Line drawing algorithm
... 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).MrSterlingBS wrote:the Demo [...]
- Tue Feb 13, 2024 12:10 pm
- Forum: Programming
- Topic: Line drawing algorithm
- Replies: 20
- Views: 4472
Re: Line drawing algorithm
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...
- Mon Feb 12, 2024 12:39 pm
- Forum: Collecting and History
- Topic: How to convert Tap files to D64?
- Replies: 11
- Views: 1581
Re: How to convert Tap files to D64?
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 ...
- Mon Feb 12, 2024 11:20 am
- Forum: Collecting and History
- Topic: How to convert Tap files to D64?
- Replies: 11
- Views: 1581
Re: How to convert Tap files to D64?
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 ...
- Sun Feb 11, 2024 2:57 pm
- Forum: Emulation and Cross Development
- Topic: Corrupt end of basic program
- Replies: 7
- Views: 1476
Re: Corrupt end of basic program
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...
- Sun Feb 11, 2024 2:40 pm
- Forum: Programming
- Topic: Line drawing algorithm
- Replies: 20
- Views: 4472
Re: Line drawing algorithm
That should be 55 cycles/pixel.MrSterlingBS wrote:00,00 to 99,99 5516 per pixel 39
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.