Reading ESDI disks

Fred Cisin cisin at
Thu Feb 11 20:29:53 CST 2021

>> On Thu, 11 Feb 2021, Paul Berger via cctalk wrote:
>>> I do seem recall using ESDI drives in a PC with 16 bit ISA slots but it is 
>>> a long time ago but I am not sure if the controller used was the RT 
>>> controller you have pictured, it seems to me the one used was a Western 
>>> Digital controller.

> On 2021-02-11 6:35 p.m., Fred Cisin via cctalk wrote:
>> The most likely ISA ESDI would be the WD1007 controller.
>> There were a few variant submodels of that, such as with/without floppy 
>> support, w/wo BIOS ROM.
>> Mine had the ROM.  On one machine, I had a 200M 3.5" drive.  My first 
>> drive of that size of both capacity and physical size.
>> I think that I know where it is.

On Thu, 11 Feb 2021, Paul Berger via cctalk wrote:
> No that is not it the one I used was a full length controller, but unlike the 
> RT controller that was pictured it did not have an IBM square aluminum can 
> chip on it, but it was probably at least 30 years ago so I don't recall any 
> more.  By the time I left the Toronto Lab where I had almost all my exposure 
> to RTs I was already using SCSI disks in my PC.

There certainly were many others.
The WD1007 that I was using (also about 30 years ago, and certainly well 
over 20 years since I turned any of that group of machines on) was a full 
length ISA board.
Some later WD1007 [sub]models were physically a lot smaller.
I think that Western Digital assigned some variant of "WD1007" with 
various suffixes as the name for all of the ISA ESDI controllers that 
they made.

A controller sold by IBM would be rebadged with IBM's own model number, 
and maybe even their own ROM, etc.
For example, IBM's HD controller for XT/5160 was a rebadged Xebec; 
I think that IBM's HD controller for AT/5170 was a rebadged WD1002.

Grumpy Ol' Fred     		cisin at

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