Search found 4683 matches
- Wed Feb 21, 2024 1:09 am
- Forum: Hardware and Tech
- Topic: VIC20 with NOS 6561 sound problem
- Replies: 4
- Views: 1477
Re: VIC20 with NOS 6561 sound problem
Even though bigger memory expansions shift things around on the VIC-20 (notably, BASIC memory and text/colour RAM), the behaviour and position of I/O (VIC and VIA) remains unchanged. a 35K RAM expansion (which I think pages in the cart memory over the built-in SRAM unless anyone can say different) T...
- Mon Feb 19, 2024 12:08 pm
- Forum: General Topics
- Topic: Jeff's VIC 20 Book
- Replies: 268
- Views: 34124
Re: Jeff's VIC 20 Book
This is a tip: To plot the cursor on position x,y on the screen: X position is on allocation 211 decimal and Y on 214. But it doesn't work because what is needed is a print HOME and a PRINT after POKE 214,Y-1. It took me hours to find out. I found the answer in Compute!'s Gazette of december 1983. ...
- Mon Feb 19, 2024 10:53 am
- Forum: Programming
- Topic: Can the display window be re-triggered? (was: 9001 when read?)
- Replies: 8
- Views: 1921
Re: Can the display window be re-triggered? (was: 9001 when read?)
Warning by viznut/pwp, for example.heaven6502 wrote:And which demo[s] use that bus trick?
- Mon Feb 19, 2024 5:51 am
- Forum: Programming
- Topic: Can the display window be re-triggered? (was: 9001 when read?)
- Replies: 8
- Views: 1921
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: 1524
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: 1921
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: 1944
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: 1524
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: 1524
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: 1378
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: 5051
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: 4736
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: 4736
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: 1717
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: 1717
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 ...