SMD disk specifications

jim stephens jwsmail at
Sat Dec 14 03:47:46 CST 2019

On 12/14/2019 1:10 AM, shadoooo via cctalk wrote:
> Hello,
> I also was searching about a clear SMD specification years ago, I found
> something in disk documentation from CDC, but doubts remain, because some
> disks call the interface SMD, some other CMD, never understood the
> difference...
CMD was the name of the division that manufactured the disks, FWIW. Not 
heard of CDC calling it anything other than SMD.  It was their golden 
goose, so though it's not really a spec, reading the specs of any CDC 
drive of an equivalent capability as you are looking for is probably 
what any standard would contain.

The big problem they faced was there wasn't a second act for them, 
despite spending huge amounts on a lot of other products.  They 
continued using oddball interfaces to try to pull the same stunt and 
people didn't fall for it twice.

The closesest that anyone came to challenging them was the Trident 
interface, but they crashed and burned anyway.

When did you see something called CMD?
> Andrea

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