Denial

I did start thinking in terms of pattern recognition within the intemediate code, so for example [...] Except it does not show the character set but merely clears the screen, that one in a post of mine dating from 2016 is actually the same example as yours: If you take the simple assignment stateme...

The data of the sprite is not correct. With VIC register $9005 set to 240, the only thing the VIC-I chip does is - displaying the ROM character set. If i change the register $9005 from $F0 (240) to $FE (254) the start text cannot be seen. As @thegg already wrote, you need to supply a copy of the RO...

Ah, I get your temporary unexpand comment... Probably not. yeah -- since the video memory map is identical, LOAD... 8,1 is necessary then SYS manually instead of RUN. The tool I linked to, "3K.PRG", temporarily 'unexpands' the VIC-20. It sets the BASIC limits and the screen position as fo...

I don't get the change between Poke 36869,240 and Poke36869,254 displayed correctly. Can someone here perhaps provide support? Judging by the disassembly, all the code ever does is writing $F0 to VIC register $900F, during init. If $900F was supposed to be changed to another value than $F0, the cor...

I'd recommend just passing [pins 20 and Y] through exactly like all other lines. There exist cartridges which misuse either pins 20 or Y on their edge connectors to simplify routing. If one cartridge connects 20 or Y to +5 V and one other cartridge connects the same pin to GND you short the power s...

I made a thing started from scratch Sunday. [...] Nice! It's an interesting idea to move up the BASIC start to $1800, so the character set sits comfortably at $1000. You might consider adding a raster split in the middle of the screen, between UI and font display, so the UI can still use the standa...

To all concerned:

MINIMON has been released on sourceforge, under the CC-BY-SA 4.0 licence.

Greetings,

Michael

orac81 was more cautious in the response, but anyway: During assembly, keep a hold of the state of the machine and comment on instructions that do not affect that state. For example: if it can be known that the carry is set, then do not assemble a SEC, but comment in the listing that that instructio...

[...] The IER does not work like a classical read/write register. Actually, the MSB specifies an action (0 = reset bit(s), 1 = set bit(s)), the lower 7 bits specify which of the interrupt sources is affected. More details here: Stop a running timer - and further discussion about the half dozen meth...

The order is important here: to initiate the BASIC warmstart, the STOP key must be held down while the RESTORE key is tapped. The other way round the NMI routine in the KERNAL will return immediately and pressing the STOP afterwards then has no effect. Does the STOP key function on its own (i.e. can...

Wouldn't this rely on an FPGA implementation of the VIC chip? That's a common misconception. As I wrote elsewhere : a complete emulation of a computer, be it a software-only as in VICE or as combination of hardware and software in a FPGA has substantially relaxed timing requirements, as ultimately ...

[...] colour clash. It's what the Speccy is famous for, but it didn't do it first. The Vic-20 beat it to colour-clash by at least a year. [...] About any home computer at that time had to compromise on memory bandwidth for the video chip. Adding lower resolution attributes to the 'B/W' display data...

In "Back in the Good Old Days" demo from 2004 I allocated chars dynamically (like a ring buffer) when drawing and eor-filling the frame [...] Char 0 was used for empty screen [...] I had 3 more "preset" chars for quickly filling 4x16 pix areas of solid colors (bit patterns $55, ...

There seems to be an odd contradiction, as more people find Dad's box of computer stuff in the loft and flog it there are more people wanting to reminisce about their first computer. Or the sellers simply count on uninformed buyers. For example, nearly all cartridges had their ROMs being dumped so ...

I struggled with those double irqs If the purpose of those "double IRQs" is to set up a stable raster IRQ, you might want to take a sharp look at this: ** Stable rasters on the VIC-20 . That is the canonical way to do this on the VIC-20, with a cycle exact timer interrupt once per frame, ...