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Here you can see photos of the modification I made to my own Dragon 64.

The attached ROMs are intended for use with the Dragon 64 to give a dual-boot (Dragon 64/CoCo 2) feature. They are intended as an alternative to this method with the added advantage of keeping the 64 mode BASIC. To use them you will need a 27128 EPROM (for the Dragon 64 "64 mode" ROM) and a 27256 EP...

I'm looking for a good copy of the schematics for any of the following Korean made CoCo 2 models:

26-3127
26-3127A
26-3127B
26-3134
26-3134A
26-3134B
26-3136
26-3136A
26-3136B


Can anyone help?

Dantyr wrote: There is any place I could grab the schematics of the Tano Dragon ?

The only schematics available are for the UK Dragon 64. They can be downloaded from http://www.dragondata.co.uk/

The MK1 Dragon 32 - Issue 2 boards (the ones with the added RAM patch boards) have a hardware fault which prevents memory above 16K being viewable via the VDG chip. The display appears very much like it does when running in POKE65497,0 double speed mode. Does anyone know why this happens, and if the...

I have now made a perfect working DW cartridge, but I did have a few problems. I spent all afternoon testing all of my game carts, searching for one that could handle double speed. Only 2 out of 19 carts could handle double speed.

The Tandy Color Computer Speech/Sound cartridge on YouTube.

http://www.youtube.com/watch?v=rM9MMq5_LNY

I discovered that the problem was caused by the 6822 PIA chip failing to operate correctly when the machine was running at double speed. Luckily I had a spare PCB with a SC67331 PIA chip. I desoldered the SC67331 from the spare PCB, and fitted it in place of the old 6822 chip. The machine is now wor...

I have a CoCo 2 (MODEL 26-3027 upgraded with 64K of RAM) with a very weird fault. If you run the machine at double speed (POKE65495,0 or POKE65497,0) the O key stops working. However, if you keep the shift key held down and press O, it works... So far I have tried replacing the keyboard, re-seating ...

Here is a copy with the problem fixed. A quick disassembly of the routine at $238A (generates sound) and you can clearly see what was causing the problem.

ENJOY!