Search found 55 matches

by MarcWalters
Fri Mar 24, 2023 9:37 am
Forum: Hardware
Topic: I'd like to propose a "FD-3000"
Replies: 23
Views: 2519

Re: I'd like to propose a "FD-3000"

Just a related but irrelevant aside: Back in the early 2000s, CMD created a custom disk duplicator that looked something like this, but in a larger case - the two drives were different devices and there was some custom ROM that allowed a copy upon sensing both disks were in.
by MarcWalters
Mon Jun 13, 2022 1:56 pm
Forum: Chit Chat
Topic: Druid
Replies: 2
Views: 701

Re: Druid

I always wanted to play this one, it looked interesting. But I never got around to it. Maybe one day...
by MarcWalters
Wed Jun 16, 2021 6:13 am
Forum: Assembly
Topic: move sprites beyond 255 x - horizontal
Replies: 2
Views: 5217

Re: move sprites beyond 255 x - horizontal

Basically, what you need to do is to maintain a sprite X coordinate in memory that can be translated into the VIC Sprite X low byte and high bit registers. The simplest way would be to store sprite X in a single byte of memory and alter its value using simple inc/dec instructions. Then: 1) Load the ...
by MarcWalters
Sun May 12, 2019 9:53 am
Forum: Assembly
Topic: Improved C64 Keyboard Reader
Replies: 3
Views: 11771

Re: Improved C64 Keyboard Reader

It works correctly. The test routine provided outputs the PETSCII character straight to the top left corner of the text screen without conversion to the equivalent screen code. The screencode for a PETSCII unshifted "A" is the spade symbol, so if you run it and press "A" then tha...
by MarcWalters
Wed May 01, 2019 1:13 am
Forum: Help!
Topic: please help
Replies: 5
Views: 5920

Re: please help

It could be that a few years ago here in Australia the RF channel historically reserved for video devices such as videogame consoles and home computers was reassigned for other uses. If there is a nearby transmitter using that RF channel then that may be causing the interference.
by MarcWalters
Tue Aug 07, 2018 7:30 am
Forum: Help!
Topic: C64 vertical lines and blank spaces.
Replies: 2
Views: 5340

Re: C64 vertical lines and blank spaces.

Ray Carlson's C64 diagnostics pages may help.
http://personalpages.tds.net/~rcarlsen/ ... 64c-ic.txt

So, maybe try swapping the CIAs (if socketed) and seeing if the screen changes. If so, then you'll need a new CIA.
by MarcWalters
Fri Jul 13, 2018 5:24 am
Forum: Help!
Topic: U22 help.
Replies: 2
Views: 4987

Re: U22 help.

The capacitor attached to the RAM IC may be marginal due to age or damage from the erratic PSU.
by MarcWalters
Tue Jun 26, 2018 8:16 am
Forum: Assembly
Topic: Improved C64 Keyboard Reader
Replies: 3
Views: 11771

Improved C64 Keyboard Reader

This is an improved keyboard reader. It's main features are: - slightly shorter - about 20% faster - not dependent on interrupts or vectors - can be used with the Kernal ROM switched out - Uses a keyboard buffer - retains all the "features" of the original Kernal ROM routine It's in C64 Pr...
by MarcWalters
Thu Apr 26, 2018 9:14 am
Forum: News and Announcements
Topic: Downtime
Replies: 5
Views: 6487

Re: Downtime

I was getting a bit worried there. Melon might be a low-traffic site, but the content is pretty good.
by MarcWalters
Fri Apr 06, 2018 8:48 am
Forum: Assembly
Topic: Ongoing Project: RESM
Replies: 0
Views: 4516

Ongoing Project: RESM

The assembly board here is a little quiet, so I might throw one of my little pet projects into the ring for discussion. I've stripped down an earlier 6502 implementation of UML State Charts and come up with something lighter and easier to use. The code presented here is fully working, but relies on ...