Search found 142 matches

by bluearcus
Sun Jun 13, 2021 12:42 am
Forum: Dragon General
Topic: DRAM data retention time
Replies: 20
Views: 44601

Re: the Delphi archives

Oh, that's unfortunate. Was fooled by the schematic which looks to suggest some spare capacity! Anyway a zip of the Delphi OS9 archives containing a 'drivepak' of those OS9 6809 system modules is on the Coco archive for download. So looks like I'll be downloading that and trying to figure out how to...
by bluearcus
Sat Jun 12, 2021 7:31 pm
Forum: Dragon General
Topic: DRAM data retention time
Replies: 20
Views: 44601

Re: Memory upgrade hijack!

I've gone old school with my upgrade: It's based on a design for the CoCo from the 80's that provides the extra address line required to drive 256K DRAMs fitted to the Dragon main board. The memory is banked in 32K pages, limiting your options as far as operating systems go, but still useful e.g. R...
by bluearcus
Sun May 30, 2021 4:00 pm
Forum: Dragon General
Topic: A DOSPlus Extender for Drivewire & CoCo-SDC
Replies: 110
Views: 111993

Re: A DOSPlus Extender for Drivewire & CoCo-SDC

The penny has just dropped... and I now understand a comment Pere made a long time ago in this thread... https://archive.worldofdragon.org/phpBB3/viewtopic.php?p=13766#p13766 To do the sector read/write data ready synchronisation, the CoCo uses HALT, which is not demultiplexed at all by the MPI, whe...
by bluearcus
Sun May 30, 2021 12:24 pm
Forum: Dragon General
Topic: A DOSPlus Extender for Drivewire & CoCo-SDC
Replies: 110
Views: 111993

Re: A DOSPlus Extender for Drivewire & CoCo-SDC

The !SCS/!P2 and !CTS/!R2 plus !CART signals are controlled by the lower and upper and nibbles respectively of the multipak control register, so it's possible to swap in the physical disk controller but keep the SDC ROM bank the same... From Ed's Mega Mini MPI design notes... The upper four bits of ...
by bluearcus
Fri May 28, 2021 6:33 pm
Forum: Dragon Hardware
Topic: Dragon expansions - FF00 page ports
Replies: 8
Views: 8582

Re: Dragon expansions - FF00 page ports

Voltmace Delta 14B multi-button joystick adapter !P2/!SCS FF40-FF43 6821 PIA, mirrored upto FF5F CoCoSDC (Dragon Mode) !P2/!SCS FF40 Emulated Disk Controller command/status reg. FF41 Emulated Disk Controller track reg. FF42 Emulated Disk Controller sector reg. FF43 Emulated Disk Controller data reg....
by bluearcus
Fri May 28, 2021 5:59 pm
Forum: Dragon Hardware
Topic: Dragon expansions - FF00 page ports
Replies: 8
Views: 8582

Dragon expansions - FF00 page ports

OK... a thread to accumulate info on Dragon FF00 page usage by expansions
by bluearcus
Mon May 03, 2021 2:13 pm
Forum: Dragon General
Topic: DRAM data retention time
Replies: 20
Views: 44601

Re: DRAM data retention time

Most interesting! So it seems that fixing the NHS signal on one of my Dragon64s was a bit of a waste of time then :-)
by bluearcus
Fri Mar 05, 2021 12:55 am
Forum: Dragon General
Topic: Comparison of Dragon mass storage options
Replies: 16
Views: 25228

Re: Comparison of Dragon mass storage options

Updated to reflect Phil's creation of OS9 drivers for the DragonMMC...
by bluearcus
Sun Feb 28, 2021 12:10 am
Forum: Dragon Hardware
Topic: Experimental Blitter
Replies: 8
Views: 8400

Re: Experimental Blitter

Wow, very very cool! :o In this demo, is there any proportion of the CPU time that's free (not setup, and unhalted) cycles? Or have you filled the frame period to the brim? My mind is always drawn to all of the time on the bus available from the inside of the machine (AVMA and !E when outside of the...
by bluearcus
Sat Jan 09, 2021 8:06 pm
Forum: Dragon Hardware
Topic: Problems with DOS using an Y-type connection
Replies: 42
Views: 35678

Re: Problems with DOS using an Y-type connection

That's really excellent news!