Denial

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...

I [...] saw your vfli mod, what you did there is superb, so you place 3k on the VIC side with hw mod. Is it possible to add more ram this way, i mean, can we add other blocks on the VIC side too? I know it is not much meaningful since VIC can utilize 4k but the display area could have been switched...

Is there a way to address this problem with this memory expansion? No. See here: https://sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?t=10385&start=7&hilit=CPU+VIC+side , and to quote from there: The 6502 in the VIC-20 cannot tri-state its address bus, therefore the address (and d...

Those 2 IRQs are not used for IO? The two VIA #2 timers control the timing of either the KERNAL IRQ (keyboard, jiffy clock, tape motor control) or the timing of tape load (T1 only) and save (T1 and T2). The VIA #1 timers produce NMIs (mostly for RS232 operations). It is somewhat possible to run sta...

;save the registers ldx #31 @ lda $9110,x sta $b9e0,x dex bpl @- That idiom isn't all that helpful to restore the state of the VIAs later - some of the registers (most notably the IER!) react differently to writes than to reads. Instead I'd simply do a SEI , then clear both IERs with LDA #$7F:STA $...

Thank you for dumping the tape, however as this is a C64 title it might be of minor interest in the VIC-20 Denial Games section. [...] if anybody has a means to convert it to a D64 file, that would be awesome. You should perhaps place that inquiry in one of the more numerous C64 forums instead. (mod...

Loading longer programs from another program. [...] At the beginning of the program the locations 45,46,47,48,49,50 must be set with the correct values. [...] Calculate the space you need, calculate the address where the space must start. These are the memory-locations that must be filled with the ...

Perhaps an incomplete, multicolor-only MG mode would be still easy to add - and very useful for VIC 20 people... Multipaint saves also to some native formats, so it could have an option to save MG picture file. You could then do some hires edits/additions in Minipaint on VIC. Put the other way roun...

I am very well aware of that. :wink: Note though even for half axes 'just' in the range 0..255, the values in the work variables E, F, G, S, T, U and V can become rather large and need 32-bit registers to store them correctly. CBM BASIC can represent these numbers within its floating point format wi...

SparkyNZ, you try to draw conclusions from the document that are not in any way backed by what is actually the case: So working with a PAL monitor, I guess the maximum display resolution for any (non-VIC) signal would be 704×576? The TV norms as such do not define any horizontal resolution in pixels...

Having mixed hires&multi characters in picture as in MG may be more tricky, as I don't know if any of the graphic modes in Multipaint currently support this (I didn't peek in the code, but this could be a design limitation in the editor, due to its multi-format nature) I had a short exchange wi...

I bet this is a question for Mike. I just happen to be the first one to answer this time, but there are also other candidates. What is the maximum number of pixels the Vic chip can display on a TV screen - this is including moving the screen from top-leftmost to bottom-rightmost? I guess you are as...