Search found 52 matches

by MarcWalters
Sun May 12, 2019 9:53 am
Forum: Assembly
Topic: Improved C64 Keyboard Reader
Replies: 3
Views: 6122

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: 4
Views: 2119

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: 1
Views: 2049

Re: C64 vertical lines and blank spaces.

Ray Carlson's C64 diagnostics pages may help. ... 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: 2398

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: 6122

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: 3239

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: 2303

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 ...
by MarcWalters
Fri Dec 30, 2016 6:17 am
Forum: News and Announcements
Topic: New Commodore 64 eBook "C64 Hardware A Compendium"
Replies: 6
Views: 3624

Re: New Commodore 64 eBook "C64 Hardware A Compendium"

I visited Amazon and viewed the preview pages. It's a shoddy, badly planned "book". Problems: The layout defies pretty much every rule of typesetting and visual design. Images and textual components are dumped in a linear fashion with no contextual indicators, no break in flow, no style an...
by MarcWalters
Wed Feb 24, 2016 4:35 am
Forum: Off Topic
Topic: Another one thinks the earth is flat...
Replies: 25
Views: 15454

Re: Another one thinks the earth is flat...

There's acknowledgement of PLAnkton in the blog's comments section. Communication and dissemination of technical information, especially in the hobby/amateur arenas, is prone to lag and omission due to higher priorities of those involved (jobs, personal life, etc). Perhaps the blogger intended to ba...
by MarcWalters
Mon Aug 31, 2015 12:44 pm
Forum: Chit Chat
Topic: eBay Madness?!
Replies: 45
Views: 14108

Re: eBay Madness?!

Most H.E.S. (Australia) game cartridge releases are being offered at artificially high prices. Double Dragon went for nearly $600. The less common ones are above $50.