Denial

Does anyone in the US know who to use to fabricate a board from KiCad? I have a circuit that I would like to have a board made from. I've been following PCBCupid on Youtube, which has been great, since I'm a beginner with board making. Any help would be appreciated. I'm at the point where I want to ...

I'm curious what you have there?

A quick tip, all the data and address line are accessible from the character ROM chip.

You are correct Pixel. The VIC 20 Programmer's Manual lists this. VIC-9005.jpg According to this, if I were to wire memory directly to the 6560, I could address memory above $9000. I don't think I'd be able to use any of it before the end of color memory, but it might be good for a small bitmap. I d...

I've been pondering the VIC I chip and the memory configuration on the VIC 20. The 6560 can access 16K of memory according to the datasheet and is indicated by the address bus of the VIC I, having 14 address lines. The 6560 can access the first 8K of memory, if the VIC20 has internal 3K. Then there ...

Hi, I was wondering what diodes are used for the 65c22N, both for the keyboard and the interrupt pin. I get a lot of characters on the screen without touching the keyboard when I use my 65c22N. The NMI seems to lock up the computer when I try to load a program from the 1541. Thanks everyone. Happy N...

My VIC has all of it's memory inside, no cartridges. Memory is installed at: $0400 - $0FFF : internal so the VIC can use it $2000 - $7FFF : internal $8000 - $8FFF : two 4K banks to share with VIC as character RAM $9800 - $9FFF : internal: IO2 IO3 $A000 - $BFFF : internal: Game RAM $C000 - $FFFF : RA...

NTSC has a total of 525 lines. I interlace mode you have 262.5 raster lines. If it takes 65 cycles to draw a complete raster line, then you would have 32.5 cycles to draw that last half-line.

Thank you for your suggestions, I will look at them.

Ok, I've got this prototype working. It's a VIC 20 with a 65C816 decoded to 128K of adressable memory. Four different versions of Commodore Basic V2.0, two with Jiffy DOS. C64 style banked memory, plus two 4K RAM banks under the Character ROM. This VIC 20 can also be turned on in stock mode also. Bu...

The last time I saw that a drive was running all the time, the problem was the rectifier in the 1541. Also make sure the head slides easily on its rail. Sometimes a drop of lightweight machine oil gets it moving.

If you want to learn more about the SAVE@ bug on the 1541 drive, then look it up in the old Transactor magazines. In volume 6, issues 1 through 4, they address the issue and give the code to burn onto an EPROM to fix the problem.

Point to point wiring can look messy. All the signals required come from all over the VIC20 board. I try to find pass throughs when possible. It has a register mapped at $9200 that acts just like on the C64, $0001. The Fast Assembler can be found in the January 1986 issue of Computes' Gazzette. Here...

I'm sure everyone has seen something like this, but this one is my custom build of my own design. What's different about this one, you ask? This one has RAM tucked everywhere. Banked under the Kernal, Basic, and Character ROMs. There are two 4K banks under the character ROM. Of course it has the int...

Brian says, address lines are having some issue. Trying to track it down. You may want to check out the address buffers and VA13. The CA13 does match up with VA13 on the schematic, it uses BLK4 to pass CA13 to VA13. What are you trying to do with the CPLD? I've tried replacing the buffers, LS245's,...