Search found 1130 matches

by sixxie
Sat Sep 26, 2020 6:46 am
Forum: Dragon Hardware
Topic: Dragon 64 - Charset issue
Replies: 8
Views: 199

Re: Dragon 64 - Charset issue

Looks like uninitialised RAM, except bit 4 is still stuck high!

Now I'd be checking the CPU and SAM are still socketed ok - you mentioned reseating them before.

Some board photos might be informative... never know.

I can't offer to attempt repair, though there are others on here who might.
by sixxie
Thu Sep 17, 2020 8:02 am
Forum: Dragon Hardware
Topic: Dragon 64 - Charset issue
Replies: 8
Views: 199

Re: Dragon 64 - Charset issue

So, for a beginner, that means maybe i should check the connection of pin 4 of the VDG and follow the line to the RAM? Sorry to ask in that dump behavior. Well, it might not be this, but the first thing I'd be checking is pin 7 of the VDG (IC10) to pin 5 of the data latch chip (IC20, a 74LS273). It...
by sixxie
Mon Sep 14, 2020 8:44 pm
Forum: Dragon Hardware
Topic: Dragon 64 - Charset issue
Replies: 8
Views: 199

Re: Dragon 64 - Charset issue

Looks like a fault between RAM chip for bit 4 through the video data latch through to DD4 (pin 7) on the VDG, seeing as everything else is functioning.
by sixxie
Wed Aug 19, 2020 3:19 pm
Forum: Dragon Hardware
Topic: Quick & dirty test for new 63C09
Replies: 4
Views: 366

Re: Quick & dirty test for new 63C09

I guess a really dumb test would be to trigger an invalid instruction trap. Try POKE359,66 - on a 6809, it'll just mangle output into graphic characters, on a 6309 it'll crash :) An immediately observable difference I find is that a 6309 takes a while longer to initialise: when you turn the power on...
by sixxie
Thu Jul 30, 2020 12:46 pm
Forum: Dragon General
Topic: Coding workflow on a Mac
Replies: 3
Views: 293

Re: Coding workflow on a Mac

Just give your ASCII BASIC files an extension of ".asc" or ".bas", and attach them as with other tape images. XRoar will automatically packet it up to load with CLOAD.

Oh, and yes, going the other way, the easiest is to use "-lp-file outfile" and LLIST.
by sixxie
Thu Jul 23, 2020 7:35 am
Forum: Dragon General
Topic: XRoar 0.36 released
Replies: 28
Views: 2712

Re: XRoar 0.36 released

Oh, interesting. I added a 256x256 icon for 0.36. It's definitely visible in the 64-bit build (when I checked, anyway), but maybe 32-bit Windows doesn't support it?
by sixxie
Sun Jul 19, 2020 12:10 pm
Forum: Dragon General
Topic: XRoar and -lp-file output
Replies: 7
Views: 728

Re: XRoar and -lp-file output

Oh, weird! I could have sworn I pushed a new snapshot just before I wrote that message. Er, rectified :)
by sixxie
Sun Jul 19, 2020 9:32 am
Forum: Dragon General
Topic: Dragon 32/64 in FPGA, help needed.
Replies: 6
Views: 551

Re: Dragon 32/64 in FPGA, help needed.

Two 16K ROMs, both resident at $8000+. Selection is with bit 2 of PIA1 side B. A HIGH value there selects the 32K BASIC ROM, a LOW value selects the 64K BASIC ROM.

There's an external pullup resistor on that line such that when configured as an input (power on PIA state), it'll be HIGH.
by sixxie
Sun Jul 19, 2020 8:46 am
Forum: Dragon General
Topic: Dragon 32/64 in FPGA, help needed.
Replies: 6
Views: 551

Re: Dragon 32/64 in FPGA, help needed.

The second ROM contains code to run from $C000+, but when mapped it's actually just switched in in place of the normal 32K ROM. A loader stub is copied into RAM which copies the ROM ($8000+) into RAM ($C000+). The correct EXEC address to kick that off is 48000. That address is just a convenience - i...
by sixxie
Thu Jul 09, 2020 9:10 am
Forum: Dragon General
Topic: RALLY SG - A new game for the Dragon
Replies: 2
Views: 474

Re: RALLY SG - A new game for the Dragon

It's good! Effective Semigraphics use, very playable. Will have to have a shuftie through it to see why it needs 64K though - maybe the map is drawn out in full into memory - twice would make sense too.