[Coco] Frustrated in Seattle

[Gene Heskett]

On Wednesday 12 March 2008, Ed Orbea wrote:
>I am getting frustrated with my attempts to utilize 3.5" floppy drives
>with NitrOS9. It is not the fault of the O/S, rather it is my lack of
>knowledge, so I am asking for some help or guidance.
>My system is a CoCo3 with a Cloud-9 512kb memory upgrade
>Either a Disto Super Controller II or a Tandy Controller (26-3129)
>Roy's VGA converter
>NitrOS9, 6809 Level II, Revision Date: 2006-03-02
>DriveWire 2.0
>
>When I use either controller, and the correct drivers, I have absolutely
>no problems with 5.25 diskettes. I have a couple of different disk drive
>configurations
>(a) Dual 360k DSDD 40 track drives (standard 40dd descriptor)
>(b) Dual 1.2m DSHD 80 track drives (standard 80dd descriptor, but using
>5.25 DSDD media)
>(c) Single 360k DSDD 40 track & Single 1.2m DSHD 80 track (standard 40dd
>and 80dd descriptors)
>On all 1.2m drives, I have pins 1-4 taped over as per previous messages
>in this group
>
>I am aware that I am "fudging the system" by using 5.25 DSDD diskettes
>as 3.25 diskettes. The descriptor for these drives/disks shows:
>Format: CoCo
>Size: 3 1/2"
>Sect per Track: 18
>Track 0, Sect per Track: 18
>Physical Cylinders: 80
>Track Offset: 0
>Sector Offset: 1
>Min Sector Allocation: 8
>Recording Format: MFM
>Track Density: 135
># of logical cylinders: 80
>Surface: 2
>Interleave: 3
>And as I said, I have had absolutely no problems with any drives/media
>but in all cases I am using DSDD media.
>
>Now, I want to convert to 3.5" media. I have purchased several TEAC
>FD-235HF drives from a local PC recycler. The TEAC drive I an first
>attempting to use (I have cleaned it out and tested it on a Windows XP
>system, and it all works correctly) is the model 4291. This model has 10
>jumpers which can be seen at:
>www.teac.co.jp/dspd/product/magnetic/jumper/fd_jumper.html
>
>This drive is set as DS1. According to the specs on this drive, HA, HI,
>HO, and LHI are used to select density mode bu either interface pin #2
>pr High Density hole selector.
>(1) I have jumpered HI and LHI so the drive will set the HD level to LOW.
>(2) I have jumpered HA which should utilize the sensor
>
>Now, I am using HD (1.44 IBM type) 3.5" media, not 720 media. I have
>tried it with the density hole covered (with black tape) and uncovered.
>Regardless of the way I jumper the drive or cover/uncover the density
>hole on the media, the following occurs.
>(1) Format the media with a default 80dd descriptor (confirmed by dmode)
>(2) The format portion completes without any error
>(3) After entering a disk name (using any text) the verify portion starts
>(4) At 0058 (hex) error 243 is generated (this seems to happen just
>after the head does a "re-seek" (my word for what happens) and the
>errors continue until I abort the format

Humm, this would be sector 94 in decimal.  There are 18, 256 byte sectors per 
side, 1 track= 2 sides=36, 2 tracks=2 sides, or 72, which leaves 1 side and 4 
more sectors for the error to show up, and this makes no sense mechanically.

Please post the output of "dmode /d1" (or whatever drive it is addressed as 
now)

>So, for those of you who are using 3.5" media with NitrOS9:
>(1) What floppy drives are you using (720 or 1.44)?
>(2) What media are you using (720 or 1.44)?
>(3) Did you modify your 80dd descriptor and if so what did you change?
>(4) Did you have to do any "jumpering" or pin-covering on your 3.5" drives?
>(5) What question do I need to ask, that I am ignorant about, and thus,
>don't know to ask?
>
Using HD media will make the drive turn up the record current if the hole 
isn't covered, but in many drives it also retunes the data separator for a 
500 kilobaud signal, and the coco can only do 250 kilobaud without mods to 
the controller.  Those mods only work with 2 of the very early controllers, 
the original shack, and one from Hard Drives International that used the 
MB7788 fujitsu FDC chip.

HD disks used in a drive set for 720k will result in a weak recording that has 
been known to fade away an hour to a month later, so its not really good 
practice to cover the hole in an HD disk to use it as a DD disk.

>Thanks
>
>Ed

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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in the image of Englishmen.
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