[Coco] A warning to readers regarding Roger Taylor

[Mark Ormond]

Direct Connect Modem Pak to Coconet Drive Pak conversion.

Parts needed
1 Direct Connect Modem Pak
1 Udrive http://shop.4dsystems.com.au/31-drive-embedded-dos-drive
1 MicroSD Card (2gb or Larger) containing the Cocopak image.
1 28 Pin Socket
1 27128 or Larger 28 pin Eprom (I used a 27512) containing the coconet rom.


Ok, look at these pics.

http://imageshack.us/f/716/20120113061412129.jpg/

http://imageshack.us/f/196/20120113062048532.jpg/


I took a modem pack and removed alot of stuff that wasn't needed anymore.

Remove IC5, T1, X2, C20, C15, C6, C7, VR1, SA1, The Phone jack, and the header going to the leds.

Cut out the original rom (Labeled IC1) and install a socket.
Then on the under side I have a jumper running from Pin 26 (A13) to IC3 (74ls133) Pin 2. If I remember right this is because the original rom is 8k and it wasn't run to the socket to support a 27128. (And yes the kynar wire did come from Radio Shack :) )
Install your coconet rom.

I mounted the udrive in place of the line jack using double sided foam tape, this allow access to the sd card from outside the case and allows the leds to be seen. I've thought about using the leds on the side of the modem, but I would have to remove the surface mount ones on the udrive. (it doesn't have headers for connecting external ones.)

>From the empty IC5 socket, the pinout is the following to connect up the udrive.

Udrive		IC5

2		14	GND
3		11	RX
4		5	TX
5		6	VCC

You can also see I've replaced the crystal with a 3.6864 one, but I don't recommend doing this until you have verified that the pack is working at the original speed. To bring this card up to the same specs as the real one, you really need to replace the 6551 with a 6551A which is actually rated for the higher speeds. Your card may or may not work with a higher speed crystal.

The other mod I've done is that you will notice a run of wire from pin 3 of the cart connector out to the connect button of the modem, and added another jumper wire to the bottom of the switch. This is a halt switch and is entirely optional.

It's a fairly simple mod hardware wise, as the modem is already at the correct address for coconet.
You could also convert a serial pak using the same basic techniques. 

I did this because when I got my coco there was a many month waiting list for the Drivepak and hey, I'm impatient.



-----Original Message-----
From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On Behalf Of Patrick Wilson
Sent: Thursday, January 12, 2012 11:55 PM
To: CoCoList for Color Computer Enthusiasts
Subject: Re: [Coco] A warning to readers regarding Roger Taylor

how'd ya do it mark?    i thought about it as well,  but not sure how i would go about it.  got a plan?
 


________________________________
From: Mark Ormond <markormond at mtxsystems.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com> 
Sent: Thursday, January 12, 2012 3:32 PM
Subject: Re: [Coco] A warning to readers regarding Roger Taylor

I built my own using a udrive and a direct modem pack.