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	[[File:J&M disk controller.jpg\|thumb\|J&M disk controller]]		[[File:J&M disk controller.jpg\|thumb\|J&M disk controller]]

	J&M Systems, LTD. CoCo disk controller cart		J&M Systems, LTD. CoCo disk controller cart

Luis46coco at 06:03, 8 April 2013

2013-04-08T06:03:37Z

← Older revision		Revision as of 02:03, 8 April 2013
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	(8/7/12) I've just made a video of this great controller in action on my Coco 3:		(8/7/12) I've just made a video of this great controller in action on my Coco 3:
	[http://www.youtube.com/watch?v=r_nrlTs_nlk youtube J&M disk controller for Tandy TRS-80 Coco Color Computer]		[http://www.youtube.com/watch?v=r_nrlTs_nlk youtube J&M disk controller for Tandy TRS-80 Coco Color Computer]

			From: [http://www.oocities.org/theother_bob/PaulDpages/jfd.html]

			J&M Disk Controllers for Color Computer<br />
			J&M Sytems produced Disk Controllers and complete drive systems including a hard drive system. There were 3 different Controllers, the original JFD-COCO, the JFD-CP and the later JFD-EC. The JFD-COCO was not compatible with a CoCo3, the JFD-EC was introduced for the CoCo3. The JFD-CP features a parallel port to drive a Centronics compatible printer or the J&M hard drive.


			JFD-COCO

			This was the "classic" J&M controller. It had a 24 pin rom socket, that usually came with a JDOS rom in it. This controller had gold contacts on both ends of the board. Utilized a Synertek SY6591 controller chip, also socketed. This was a good controller till the CoCo3 came out, and it did not work with it. J&M initially recommended changing the 74LS04 to a 7404, but this did not always solve the incompatibility. The final modification was to substitute the Q clock signal in place of the E clock, basically a trace cut and adding a jumper. Simply cut the E clock line (Pad 6). Solder a jumper wire to the Q clock (Pad 7) and connect it to the controller. I used a through hole beside U17 to make the connection on one controller I modified. The controller will now work with the CoCo3 and the CoCo2. If you have a 24 pin JDOS rom, it will also not work with the CoCo3, swap in a RS DOS 1.1 or something such as ADOS 3. See Rainbow, May '87, page 174 for more information.


			JFD-CP

			This was the second and most deluxe controller that J&M built for the CoCo. Externally it appears different than the original as there is now a toggle switch to select which rom to use, and a header connector which is the built in parallel port. The Hard Drive unit to connect to this controller was originally a 5 Mb Seagate, enclosed in a self contained drive/power unit with built in interface that connected directly to the Centronics compatible printer port. Software to drive it was OS-9 only.


			[[File:Jfd-cp.jpg\|framed\|jfd-cp]]

			JFD-CP Parallel Port

			PIN FUNCTION SOURCE <br />
			1 Write Strobe Controller <br />
			3 D0 Bi-directional <br />
			5 D1 " <br />
			7 D2 " <br />
			9 D3 " <br />
			11 D4 " <br />
			13 D5 " <br />
			15 D6 " <br />
			17 D7 " <br />
			19 Read Strobe Controller <br />
			21 Busy External Device <br />
			23 N/C <br />
			25 Status External Device <br />
			26 Reset Controller<br />

			All even pins 2-24 are ground

			This connector will allow most Centronics compatible printers to operate with the JFD-CP using a standard, unmodified Radio Shack Model 100 printer cable.

			Pinout from page B-3, JDOS Disk Basic Reference Manual, J&M Systems



			JFD-EC

			The EC stands for economy. This controller was brought out to get J&M back into the lower cost segment of the disk controller market. This controller has a toggle switch to select one of the dual roms, and now supports a 16K device. Cost savings were obtained by eliminating the parallel port , and utilizing the SY6591 controller chip, which J&M apparently bought the entire inventory of when Synertek went out of business.



			Thanks to Alan Stallings, formerly of J&M, for correcting some errors and providing more information.

			Page last updated Dec 24/2001

Luis46coco: Created page with 'J&M disk controller J&M Systems, LTD. CoCo disk controller cart Considered one of the best disk controllers for the TRS-80 Color Computers…'

2012-09-08T03:07:50Z

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[[File:J&M disk controller.jpg|thumb|J&M disk controller]]
J&M Systems, LTD. CoCo disk controller cart

Considered one of the best disk controllers for the TRS-80 Color Computers.
They have gold connectors and are engineered to a very high standard

Internally has JDOS 1.11 rom on it for fast (6ms) disk drive stepping.

(8/7/12) I've just made a video of this great controller in action on my Coco 3:
[http://www.youtube.com/watch?v=r_nrlTs_nlk youtube J&M disk controller for Tandy TRS-80 Coco Color Computer]

J&M/Owl-Ware - Revision history

AllenHuffman: adding Nav template

Luis46coco at 06:03, 8 April 2013

Luis46coco: Created page with 'J&M disk controller J&M Systems, LTD. CoCo disk controller cart Considered one of the best disk controllers for the TRS-80 Color Computers…'