Denial

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...

Hi, I only use VICE. It happens 10% of the savings, and mostly at the end of the disk-directory or at the end of the tape. I made backups. I made a backup of this program with this error and didn't touch it after that. The backup is fine, curious. Other strange thing: I make backups of the floppies....

What tool did you use to create the program file in first place? This error is typical for a BASIC program file that for whatever reason was saved with a missing last byte . By itself, the SAVE command of BASIC does not produce that problem - but once a BASIC program is loaded that has been produced...

srowe wrote:I guess [the RTC is] used to set the timestamps of files written to the SD card.

This.

Unfortunately, many other (commercially available) SD2IEC drives economize on this aspect.

To be specific, I have a copy of some VIC 20 Diagnostic firmware that has a bug when it comes to determining how to display on the screen (I get odd colors). Are you sure this is not due to a hardware bug (faulty colour RAM, for example) in your VIC-20 itself? In that case it would be a waste of ti...

I was able to get it down to under 15 cycles per pixel on average? That would imply your routine accesses/modifies each involved bitmap byte only once, i.e.: having LDA - ORA/EOR/AND #imm - STA present and inlined for all 36 possible horizontal line segments, removing all further address arithmetic...

Mike sum[s] up the challenge with adding memory visible to the VIC chip, but, I made a prototype circuit that will fix this problem. Just for the record, I solved said "challenge" or "problem" years ago already with aforementioned VFLI mod, by installing the RAMx range memory on...

How can I make sure the font file has the proper load address? The load procedure with SYS57809 ... SYS65493 that I highlighted above forcibly loads the font file to $1400, yet still a load address needs to be present as first 2 bytes of the file (making it 2050 bytes total). I have checked the fil...

ricky_derocher wrote:What would be the poke(s) needed to set the font for $1000?

You normally would not want to do that as then the text screen and character set are at the same position.

The first usable position for the font then is at $1400, see my edited post above for more details.

Just "bload" the font 9 block font file into place, and then POKE the right address to change to the font. That works quite the same on the VIC-20. VIC register 36869 sets the character generator base address (bottom 4 bits) and the screen start (top 4 bits, together with the top bit of 3...