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TRS-Ian
January 18th, 2015, 07:36 PM
A few people have asked me over the years if I have a floppy disk controller (FDC) for the Tano Dragon 64, because apparently the TRS-80 Coco FDC doesn't work.

Come some people in the know tell me why it doesn't work and will an Eprom upgrade or other hardware mod make it work?

I currently have no Dragons to test, but don't want to re-invent the wheel if there is a known way to make a Coco FDC work on a Dragon.

Thanks in advance,

Ian.

TheCorfiot
January 19th, 2015, 12:22 AM
It is indeed doable.
I have a self modified 26-3022 controller with a switchable dual Rom which works perfectly in both RSDOS mode and DragonDos.

All Dragon 32 and 64 machines carry the +/- 12V on the cartridge port so the 3022 operates correctly.

I can email you the Rom image ready to program or i can put together a how to for TRS8bit...
But it really is just a Rom replacement.

:)

jltursan
January 20th, 2015, 12:38 AM
What kind of mods have you made to the 3022?, only the double sized EPROM?
Never tried it; but does the 3022 work without -12V?. The Dragon slot connector doesn't provide this voltage (IIRC the Dragon 32 internal PSU doesn't not even generate it).
Posting a guide would be great tho :-)

TRS-Ian
January 20th, 2015, 02:18 AM
Thanks Corfiot,

So basically to summarise, the Dragon cartridge slot is electrically compatible with the Coco cart slot, and its just the contents of the Prom/Eprom which makes the difference. Sound like all Coco FDCs will work with the correct Eprom?

I've ordered me a Tano, so I'll try it out when that arrives.

Cheers,

Ian.

TheCorfiot
January 21st, 2015, 12:21 AM
Hi guys

Yes it is fully cartridge slot compatible.
The 3022 only uses +12v and +5v so the lack of -12v is not a problem.
If i get a chance later i will take some photos of my 3022 whuch i use with both TRS80 Coco1,2 and 3 (Muktipak required for 2 and 3 due to missing +12v) and various Dragon 32's with no issues


TC :)

jltursan
January 23rd, 2015, 12:11 AM
Cool, thanks!

Al Hartman
March 10th, 2015, 06:08 AM
A true Dragon disk controller is different than a Coco controller. It addresses the disk controller chip differently. But, as long as your software does not try to bypass Disk BASIC and directly address the disk controller (like OS-9 or NitrOS-9), it should work with the disk controller.

Here is someone who has made a Dragon Compatible controller (It's in Spanish): http://hardware.speccy.org/temp/Dragon-1.html

jltursan
March 12th, 2015, 01:12 AM
Yep, I have two of these boards and they work great. They're a clone of the original DragonDOS cart, just a little smaller.

Easy to build; but tricky to calibrate if you don't have an oscilloscope.

Al Hartman
October 24th, 2015, 03:53 PM
I have a TANO Dragon 64 and an extra disk controller I'd like to modify into a Dragon Controller.

Can you send me the ROM image, or point me to where I can download it?

TRS-Ian
October 24th, 2015, 04:14 PM
You can get them from my site:

DragonDOS on it's own (8Kb) http://ianmav.customer.netspace.net.au/downloads/dratrs.rom

or

DragonDOS and RS-DOS (16Kb) http://ianmav.customer.netspace.net.au/downloads/dualfdc16k.rom

(You need to add a switch to change between DOSes when using the 2nd file.)

Cheers,

Ian.

Al Hartman
October 24th, 2015, 04:19 PM
You can get them from my site:

DragonDOS on it's own (8Kb) http://ianmav.customer.netspace.net.au/downloads/dratrs.rom

or

DragonDOS and RS-DOS (16Kb) http://ianmav.customer.netspace.net.au/downloads/dualfdc16k.rom

(You need to add a switch to change between DOSes when using the 2nd file.)

Cheers,

Ian.

Any instructions on how to add the switch?

What kind of EPROM would I use for 16k?


Added: Thanks Ian!

TRS-Ian
October 24th, 2015, 04:53 PM
I'll do one and let you know. The Corfiot explained how to do it. From memory it's like any 24-pin to 28-pin eprom upgrade: the 4 extra pins need to be wired somewhere else on the PCB, and one line (A13?) goes to a switch where High selects the top 8K and Low selects the bottom 8K...

Hope this helps,

Ian.

TheCorfiot
October 25th, 2015, 04:28 AM
Hi guys.

The firmware Ian has on his site are the ones i sent him and are proved to work.
i dont have time today but will take my cart apart tomorrow and publish some pictures...and instructions.

It's an easy mod with no board mods or hookup wires if i remember.

:)

JonB
October 26th, 2015, 04:30 AM
I wonder where I could get one of those boards from that the Spanish guy had made? He must have spares...

icbrkr
October 26th, 2015, 04:06 PM
I did this earlier this year.. some pics:

https://www.facebook.com/icbrkr/media_set?set=a.10205153996387445.1073741860.11709 07465&type=3


I luckily had a 2564 ROM lying around from another project.

The Retro store (http://store.go4retro.com/2364-adapter/) has adapters for 28 ->24 for a pretty reasonable price.

jltursan
October 27th, 2015, 12:30 AM
I wonder where I could get one of those boards from that the Spanish guy had made? He must have spares...

I can ask him; but I think that he doesn't keep any spare PCB. He made a batch of PCBs some time ago; but after that it focused its efforts in the QL's QubIDE :rolleyes:

TRS-Ian
October 27th, 2015, 04:13 AM
Ok I did one this evening and tested it on my Tano Dragon 64 and it works great. I used the 8K dratrs.rom burned to a 2764 Eprom and installed it in a 26-3129 CC FDC (a.k.a FD-500 FDC). Here is how I did it:

Burn dratrs.rom to a 2764
Bend out Pins 1,2,20,23,27,28
Remove the old RS-DOS Rom and insert the 2764 into the socket with pins 1,2,27,28 overhanging at the front.

Run the following wires:
2764 Pin 20 to a Gnd source (black wire in picture below)
2764 Pins 1,27,28 to a 5VDC source (red wire in the picture) to the positive side of the electro-cap which filters the 5VCD coming in from the cartridge port
2764 Pin 2 to socket underside pin 21 (A12 line, for those interested)
2764 Pin 23 to socket underside pin 18 (A11 ditto)

2750627507

Plug it in and try it out. Remember when formatting a diskette that DSKINI0 command has changed to DSKINIT

Discuss.

Ian.

jltursan
October 28th, 2015, 12:27 AM
So, absolutely no change in the DragonDOS ROM?, nice!

Now you only need to get a 27128, join and burn both rom and using a switch, wire A13 to +5V through a 4.7K resistor or to ground depending switch position. This way you'll switch between 8K banks.

TRS-Ian
October 28th, 2015, 02:32 AM
Just made a switchable one, see photos below. Tested on my Coco 3 and Tano 64. Parts needed: 27128 Eprom, a switch, and some wires.

Here's how:

Burn dualfdc16k.rom to a 27128
Bend out Pins 1,2,20,23,26, 27,28
Remove the old RS-DOS Rom and insert the 27128 into the socket with pins 1,2,27,28 overhanging at the front.

Run the following wires:
27128 Pin 20 to a Gnd source (black wire in picture below - this time I wired it to Pin 14 (Gnd) on the Eprom)
27128 Pins 1,27,28 to a 5VDC source (red wire in the picture) to the positive side of the electro-cap which filters the 5VCD coming in from the cartridge port
27128 Pin 2 to socket underside pin 21 (A12 line, for those interested)
27128 Pin 23 to socket underside pin 18 (A11 ditto)
Mount a small switch in the case (see picture, below)
27128 Pin 26 to the centre post of the switch
Run wires from the other two posts on the switch - one to Gnd, one to 5VDC
(see picture, below)

2754727548

The place I put the switch was chosen because whether the FDC is plugged into a Coco 1,2,3 or Dragon, or a MPI its easy to reach (if needed) but sufficiently out of the way so you won't accidently knock it to the other DOS in the middle of a 5 hour programming session.

Discuss.

Ian.

TheCorfiot
October 28th, 2015, 11:51 AM
Hi Ian

i notice you didnt use the switching scheme i described to you...
I wouldnt advise connecting 5v and 0v directly either side of the switch as you are prone to shorting your PSU if the switch fails.

Run a 4k7 resistor between 5v and pin 26...then run a length of wife to a simple SPST on off switch from pin 26 and any ground point.

I appreciate Ian describing the mods here as i havent had the time to photograph and document it myself...

Please note the Dragon firmware is NOT from Dragon Data, it is a modified version to allow the DOS to work on the CoCo's different FDC controller.

Regards
TC :)

jltursan
October 28th, 2015, 12:06 PM
Please note the Dragon firmware is NOT from Dragon Data, it is a modified version to allow the DOS to work on the CoCo's different FDC controller.

Thanks for clarifying this, that makes more sense to me. So it must implement the HALT/FIRQ conversion...

Indeed is nice to see it working thanks to Ian's post :-)

TRS-Ian
October 28th, 2015, 02:13 PM
Hi everyone, video shows the DragonDOS-only FDC running on my Tano 64:


https://www.youtube.com/watch?v=C9U4MakU80U

Ian.

TRS-Ian
October 28th, 2015, 03:11 PM
And this video shows the other FDC I did last night with the switchable RS-DOS 1.1 and DragonDOS:


https://www.youtube.com/watch?v=tBWq4VoQmqA

Ian.

TheCorfiot
October 28th, 2015, 03:16 PM
It was a pleasure sharing it with you Ian, thanks for the acknowledgement.

:)

TRS-Ian
October 28th, 2015, 03:21 PM
Thanks Bas, and everyone else, I've needed a kick up the ass to get onto this project which has been in the back of my mind for years.

Al Hartman
November 11th, 2015, 04:16 PM
Don't you mean a SPDT switch?

I'm going to try this. I ordered the switch and resistors. Gotta track down my full sized cartridge.