Search found 530 matches

by sorchard
Fri Jan 14, 2022 9:34 am
Forum: Dragon Hardware
Topic: D64 with new Dragon PSU issue
Replies: 12
Views: 8745

Re: D64 with new Dragon PSU issue

I would use an oscilloscope to see how much ripple there is on the supplies. The fact that it works when more current is drawn suggests one of the supplies is moving to a more stable region, which in turn suggests an incorrect component value. A component value could be incorrect because it was put ...
by sorchard
Mon Jan 03, 2022 9:45 pm
Forum: Dragon Hardware
Topic: Display bars
Replies: 2
Views: 2573

Re: Display bars

Hmm, strange one. In my experience, jail bars on Dragons are usually caused by missing bypass caps on the DRAM array, and fitting all eight 100n caps virtually eliminates them. I don't think I've ever seen hum bars on a Dragon. That tends to indicate a fault, particularly if you say 1u caps didn't m...
by sorchard
Thu Dec 30, 2021 12:07 pm
Forum: For Sale
Topic: Blockdown cartridges for sale
Replies: 2
Views: 7699

Re: Blockdown cartridges for sale

Love the artwork! Brilliant :)
by sorchard
Sat Dec 11, 2021 5:32 pm
Forum: Hints and Tips
Topic: Some useful short 6809 routines
Replies: 2
Views: 8577

Re: Some useful short 6809 routines

Cool. Thanks for sharing :) There is an old trick for converting a binary digit to ascii hex that is fewer bytes than the branching version: adda #$90 daa adca #$40 daa Also, I wonder how the long multiplication compares with a version that uses 6809 MUL (8x8) to generate the partial products.
by sorchard
Fri Dec 03, 2021 8:58 pm
Forum: Dragon Hardware
Topic: Dragon 64 internal DS1315 RTC board
Replies: 10
Views: 8924

Re: Dragon 64 internal DS1315 RTC board

Doesn't RTI spit a dead cycle at the end though?! It does, but the beautiful thing is that it emits the stack pointer during that cycle rather than FFFF :ugeek: Something similar happens to allow say LDA ,X to work. It runs for four cycles: First two cycles are opcode and postbyte, then there is a ...
by sorchard
Fri Dec 03, 2021 6:33 pm
Forum: Dragon Hardware
Topic: Dragon 64 internal DS1315 RTC board
Replies: 10
Views: 8924

Re: Dragon 64 internal DS1315 RTC board

Not quite sure where this lies on the filthometer, but one code trick I'm fond of is using rts with a preloaded stack as a fast loop counter or sequencer. A similar thing can be done with puls regs,pc to quickly make a series of function calls with parameters. This approach is nicer because it respe...
by sorchard
Thu Dec 02, 2021 4:40 pm
Forum: Dragon Hardware
Topic: Dragon 64 internal DS1315 RTC board
Replies: 10
Views: 8924

Re: Dragon 64 internal DS1315 RTC board

Just some proof of concept code to access the rtc without switching roms.

Should help with getting one of these working in a Dragon 32.
by sorchard
Wed Dec 01, 2021 8:55 pm
Forum: Dragon Hardware
Topic: Dragon 64 internal DS1315 RTC board
Replies: 10
Views: 8924

Re: Dragon 64 internal DS1315 RTC board

That's some pretty tenacious coding you've pulled off there to access the rtc :)
by sorchard
Tue Nov 23, 2021 9:04 pm
Forum: Dragon General
Topic: Project 2
Replies: 56
Views: 75491

Re: Project 2

The hi score table looks great, and I don't even need to add the qualifier 'for the Dragon'! It definitely captures the arcade feel :D
by sorchard
Fri Nov 19, 2021 4:54 pm
Forum: Dragon General
Topic: XRoar 1.0 released
Replies: 49
Views: 100557

Re: XRoar 1.0 released

can you point me to the download link. i can't find it. sixxie only had time during his lunch break to push a source update, which I was able to build and can confirm it fixes my issue: So cheers @sixxie for that :) Also @sixxie Many thanks for the updated manual. Very nice. One thing with the buil...