[Coco] Driect Connect Modem pack to Drive pak conversion.

Mark Ormond markormond at mtxsystems.com
Tue Nov 2 00:28:50 EDT 2010

I scored a Direct Connect Modem Pak off ebay with a joystick and Orchestra 90-cc pak for cheap.

I really don't need a modem, so I decided to try to make it into a drive pak.

To do the basic conversion you will need.

1 28 Pin socket.
1 udrive
1 microsd card.
1 27128 thru 27512 (your choice) eprom with coconet. If using a larger rom, just repeat the image till the rom is filled.

Cut the rom from the modem pack and install the 28 pin socket.
Run a jumper wire from pin  2 of ic3 (74ls133) to pin 26 of the rom socket.
(This enables A13 on the socket, thus giving us 16k eprom capability)

Go ahead and install your eprom and make sure coconet comes up.

Now turn over the board and solder a jumper wire between pins 16 and 17 of the 6551 uart (IC2)

Next up, cut out the modem chip located at IC5 (74HC943n) (Yes this chip is a 300 baud modem)

Now from the empty socket The pins you will need are as follows.

Pin 5 RXD
Pin 6 VCC (+5)
Pin 11 TXD
Pin 14 GND

Socket	Udrive

5		4
6		5
11		3
14		2

Please double check and triple check your connections here.

>From the Udrive check for continuity to the following.

Udrive		card edge pins

2			33
5			9

Udrive		6551 Uart (IC2)

3			10
4			12

Now throw in your microsd card that you have written the distribution image to using Cocopak and turn on the coco.

Right now it's running at 115200, I'll swap the crystal when I have a chance. 
I don't have reset for the udrive hooked up at the moment either.
I've also rigged up the connect switch as a halt switch and 
I'm going to use the mode switch for hi low eprom bank select (a14).
The card just fits thru the modem phone jack hole, and the udrive is held in place with double sided foam tape. (From Radio Shack of course)

Thank you for all your hard work Roger.

Please support Roger and his work. Without it, this hack wouldn't have been possible.

More information about the Coco mailing list