Denial

Interesting! So I assume the mixing equation is something like this?

I finally had some time to work on this. I built this on a breadboard and it works! Next I'm going to etch a PCB. Then I'm ready to start coding something for the VIC :) Full write up with schematics and photos in my blog: http://petenpaja.blogspot.fi/2014/01/vic-20-flash-memory-programmer-part-12.h...

Whoah! I made the S-Video mod and the difference is like night and day! Here are before and after shots: https://www.dropbox.com/sh/r6yzay1s0bpuoyw/tuI-o7Tt1c?lst#/ There is still some blurry vertical stripes visible in the image (hard to see in the photos). Probably caused by the 1 Mhz noise in the...

Yeah, I suspected that the bus is not in high impedance state even in reset. Thanks for the confirmation!

Yes, the plan is to use USB->serial converter between MCU and host PC. I hope to get some free time during the christmas holidays to work on this. I'll post results here.

Michael, thank you for the speedy response! I'm very glad that it's not caused by a broken video chip :) I have the same pal cr model as jibberjabber so this is most likely the cause. It is interesting that they used square wave to approximate the sine wave in the vic. Same trick is still used today...

Hello! Does the image quality of the following photo look normal to you? To me solid colors look quite bad, lots of variance in luminance. A horizontal raster pattern is clearly visible where solid colors should be, even in borders. I don't know if this is normal or not, since I haven't seen output ...

Hi there! I'm planning to build a device for the expansion port which should allow fast cross-platform development and I'm looking for comments on the feasibility of the project and also on any glaring errors in the design :) The cartridge should have the following features: - vic-20 can see the fla...

Hi guys and thanks for the kind words! The game works incredibly well as a party game. The game has only 15 rooms so It takes just about three minutes to finish the game if you know what you're doing. But getting a high score is a completely different matter. It takes many, many hours to find the op...

I made a 8-bit game console and a game for it. Check it out!
http://petenpaja.blogspot.fi/2013/11/to ... -game.html

I may consider doing a VIC-20 port if I can find enough free time

Memory addresses $1000-$1fff map to the two 2k x 8 SRAM chips, U15 M58725P and U14 M58725P in the VIC-20cr schematic, unless I'm mistaken. The lower 2k maps to U15 and upper 2k maps to U14. Please note that I'm a total newbie and I just found this out by looking at the schematic, so take this with a...

Thank you for the detailed answer. I'm trying to learn everything I can about the VIC-20 and your answer was very helpful.
Then, I guess when creating new cartridges it's better to design for the older model. 1A sounds plenty enough to me.

6502dude wrote:Have a look at Vic-20 MegaCart also for ideas.

Speaking of which, I ordered the MegaCart a few days ago but haven't got any email back. Hope all is well and I get the ultimate MegaCart one day…

Thanks! 250mA should be plenty enough. It's a bit weird though that max rating for the expansion port is so much higher than the user port...

Does anybody know how many milliamps I can safely pull from the +5V pin of the expansion port? I know the maximum rating for user port and joystick port is 100mA, but Google is very silent about the expansion port...

Thank you orion70! Interesting read. If somebody has the schematic still around I'd be very grateful..