[Coco] Re: Any documentation or info on Tandy's Coco hard disk controller?

[John E. Malmberg]

Ward Griffiths wrote:
> 
> There is that.  I need to study those schematics to see if they can be 
> adapted to the 7300/3B1 or even the Tandy 6000.  My stash of mfm ST-506 
> interface drives is gradually dying.  Got a handful of ESDI drives with 
> nothing to put them in, if anybody's interested.  La Esposa is always 
> at me to clear stuff out of the basement, and I don't have an emotional 
> attachment to the ESDI drives.

I do not have an ESDI controller, but they were quite popular in the 
older mini-computers as third party upgrades to MFM drives.

As you probably know, the big problem with drives that old, especially 
ones that are in storage is that the likely hood of failure is high, so 
it would be hard to get anyone to pay good money for one.

A post on comp.os.vms OR vmsnet.pdp11 that you are selling cheap or 
giving away ESDI drives would probably get the best response if anyone 
is still interested in drives that old.

And it is sad, but many companies spend many times more money buying 
these old drives on the used market to keep old equipment going than it 
would take to upgrade the equipment to use the modern disk drives.

But they do not have any one that really understands the equipment and 
the economics involved, and are afraid to change anything on a process 
that "works", no matter if not changing it is the more expensive and 
risky procedure.

I know of a firm that had a system that used a particularly fragile and 
obsolete disk system.  It would have cost them about $2000 using premium 
components (> $1000 using adequate components) to convert it over to use 
modern disks that were readily available.  The conversion was trivial, 
plug in new hardware, copy the data, unplug the old hardware.

The conversion was not done until it became impossible to buy 
replacement disks anywhere at any price.  Had the conversion cost been 
done at the time that the original disks became obsolete, it would have 
paid for it self many times over.

It's sad to have companies making decisions like that, when we know that 
we can do things better and cheaper.

-John
wb8tyw at qsl.net
Personal Opinion Only