[Coco] Jumper settings needed

[Tony]

----- Original Message ----- 
From: "LinuxRules" <Linux-Rules at austin.rr.com>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Thursday, October 02, 2008 9:12 PM
Subject: Re: [Coco] Jumper settings needed


> Tony wrote:
>>
>>
>> I have  a Revision L and Revision U M4853 in front of me.
>> I KNOW I used my Rev U in a PC, as it still has a diskette inside 
>> labelled "MS-DOS."
>>
>> On the jumper set near the FDC connector, DS1 is jumpered, and HM is 
>> jumpered.
>> Going rear (nearest connector) to front (towards front of drive) using 
>> binary:
>> 01000010  1 being jumpered.
>>
>> Mine also happens to have the term jumpers inserted, whic is about 1 inch 
>> away from edge,
>> about 2 inches in from the FDC connector.
>>
>> Rev U and Rev L are VASTLY different on other jumpers, ie, not the jumper 
>> header where DS is
>> selected.
>>
>> Tony
>>
> I appreciate all the help Tony!
>
> Checking my drive, it's a Rev C. Early one, I guess.
> It has 7 positions, not 8, for the option block near the connector.
> The good news is that there is one labeled HM, so I set the jumpers
> to HM - was DS - and DS1 - where it already was.
> The bad news is that produced no change. Arrggg.!
> Well, actually, it did make one change - the head started pounding
> up & down a dozen or so times as the PC tried to identify the
> drive. But, no change in the "Not Ready" problem.
>
> I also used your suggestion of setting BIOS to 720K, but
> that also produced no improvement.
>
> Guess I gonna have to order the manual(s) from "herb's stuff"
> web site. Unfortunately that seems to be a slow process as
> you have to Xchng email with him to select the right manual
> and get a quote, then send snailmail with a check and he mails
> the manuals. Most likely has to wait for check clearing also.
>
> Ah well, if you gotta, you gotta........
>
> As a side note, my search for M4853 returned dozens of replys
> (no jumper data) and about 2 dozen claimed that it is a 360K
> drive. One claimed 400K (vote for 360!). One claimed 0.72Mb.
> One claimed 80trk, 720Kb. And one claimed 96tpi, 720Kb.
> Dern, now I don't know for sure ?WHAT? I have...
> Possibly the difference between M4853 and M4853-1 could
> perhaps be the track density....48tpi vs 96tpi??
>
> Confusion reigns.
>

There is no confusion - any old-school, long-time CoCo'er should be able to 
tell you
that the M4853 is a 5.25" 720KB DS/QD 80-Track , 96tpi drive.
The DS/DD 360KB drive is the M4851, as I have those, too, and transplanted a 
pair
into a Morrow MD3 CP/M machine. Same funky mechanism.

The M4853 drives were OEM in the Tandy 2000, which was just one of many 
reasons
the machine failed, and us old-time cocoers ganked them for use as /D1 and 
/D2, to have
a 360K and (2) 720K drives online.

I have about 6 of these drives, and have used them on my PC (Acer P75 with a 
CompatiCard IV)
to images disks for Altos 580 / Series 5, which is, you guessed it, DS/QD 
5.25" 720kb media.

Whoever is telling you the M4851 is 360kb or 400kb has no idea what they are 
talking about.

For example, the Tandy 2000 faq mentions the Mitsubishi DS/QD 720kb 
floppies:

http://www.geocities.com/siliconvalley/lakes/6757/t2kfaq.txt

In sections 3, 4, 14

Check out the Tandy 2000 Service Bulletins to see if any info is in there:

http://www.geocities.com/siliconvalley/lakes/6757/t2k_serv_bulletins.pdf

And check out Rich Cini's comprehensive Tandy 2000 site:

http://highgate.comm.sfu.ca/~rcini/systems.htm

Tandy 2000 is at bottom, and he has PDF versions of the Tech Ref manual 
here:

http://highgate.comm.sfu.ca/~rcini/pdf/Tandy/Tandy%202000%20Technical%20Reference.pdf

Which mentions the Mitsubish BY MODEL on page 183, section 7.3.1

Link to RadioShack, where the first paragraph describes the drives:

http://support.radioshack.com/support_computer/doc1/1294.htm