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 EPROM (for the combined CoCo 2 and Dragon 64 "32 mode" ROMs). You will need to isolate pin 27 (A14) of the 27256 EPROM from the PCB and add a switch (or jumper) to switch between CoCo and Dragon mode ROMs. See the following attached pictures for a working example of the modification.
These ROMs were sent to me by Steve Woolham without any documentation other than a few quick notes in the Email. I have written a short list of the changes that I am aware of below.
CoCo ROM changes:
* Improved Dragon compatible keyboard routine
* PCOPY bug fixed
* PCLEAR command now supports freeing all graphics pages (PCLEAR 0)
* 6309 error trapping support
* PLAY and SOUND commands patched for use with Dragon hardware
* RKEYS ON/OFF - Auto-repeating keys feature (replaces the DLOAD command).
* Supports printing via the Dragon 64s parallel printer port
Changes to Enhanced Dragon 64 ROMs v3.0:
* Improved 6309 error trapping support
* RKEYS toggles keyboard auto-repeat on/off (replaces DLOAD command)
EDIT: Archive updated on the 9th of February, 2013.
CoCo ROM changes:
* Keyboard auto-repeat routine now uses bytes $E7 and $0114 instead of $F7 and $F8 to avoid conflicts with HDB-DOS.
* Slight speed tweak made to the keyboard auto-repeat routine
There is no need to de-solder the switch or resistor if you have already done the modification to your Dragon 64. I did the update as follows.
(1) Remove the EPROM (IC18) with switch and resistor attached.
(2) Make sure the switch is in the OFF position, and put the entire assembly into your EPROM eraser.
(3) Make sure the switch is in the OFF position, and place the EPROM into the ZIF socket of your EPROM programmer.
(4) Re-program the EPROM with the updated ROM image.
