Denial

After a very long time (35+ years), I have finally written my first VIC-20 game. Concentrate is a numeric puzzle game and a full description is provided in the attached zip file. Basically, the challenge is to fill in the hidden numbers in a 7 by 7 grid so that each diagonal, row and column sum to a...

Chysn Thanks for confirming my program works on a real NTSC machine. Appreciated. As for checking the video type, I can see that inspecting the initialisation list is as good as any and more reliable than most way to go. So that is what I will do when the need arrises. Mike Thanks for taking the tim...

Michael thanks for the additional information. Since your last comment I have been chewing over the possibility of roms being different. I accept that your preference is based on loads of experience, but logically is it not possible that a rom replacement such as JiffyDos might move the Vic initiali...

chysn Thanks, that is what I was seeking, something in ROM specifically identifying the chip type installed. Using the various advice above (except for disabling the Restore NMI) I have modified the demo to adjust the various timing values according to whether it is running on a PAL or NTSC machine....

Many thanks Michael. I've downloaded your example and will take a look when time allows.

Dave

Doesn't really look as intended on NTSC! Not surprising as I was working from the specs for the PAL version. My understanding from the Denial WIKI is that the NTSC VIC chip is different to the PAL version in screen size, frame rate and lines per frame. Are these the only practical differences I need...

Thank you all for the very quick response.
Mike thanks for taking the trouble to look at the code. Your comments are appreciated and I shall look into them in some detail.
One thing I've taken note of from all the replies is that I need to think both PAL and NTSC when posting in the future.

Dave

Hi everyone, Having just restarted playing with the VIC-20 after a lifetime of work, I wanted to find what I could do with an unexpanded machine and very rusty 6502 assembler knowledge. So I have put together a little technology demo that explores some of the VIC-20 capabilies that interest me. Ther...

Hello, A few lines to introduce myself. I am fairly recently retired having spent 30+ years working as a Computer Systems Engineer in the UK. Like others on this forum perhaps, I have returned to my first computer (the VIC-20) as a way of entertaining myself and keeping the grey matter stimulated. I...