Re: SMD disk specifications
On Sat, Dec 14, 2019 at 2:47 AM jim stephens via cctalk < cctalk@classiccmp.org> wrote: > CMD was the name of the division that manufactured the disks, The division was Magnetic Peripherals Inc. (MPI). I've never heard of it having been called CMD either before or after it was called MPI. There was an (AFAIK) entirely unrelated company named CMD Technology Inc. that made disk controllers. FWIW. Not heard of CDC calling it anything other than SMD. According to CDC and MPI documents on various drives, and the SMD/MMD/CMD specification document: SMD = Storage Module Drive MMD = Mini-Module Drive CMD = Cartridge Module Drive These were separate groups of products, though they obviously had similarities, and the interface was essentially identical. > 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. There's most definitely an interface specification that is not specific to any given drive. For original SMD/MMD/CMD, it is CDC document 64712400, which went through many revisions, some of which can be found on bitsavers: http://bitsavers.org/pdf/cdc/discs/interface_specs/64712400_SMDCableSpec_Mar81.pdf The technical specifications of any given drive model give a substantial faction of the interface specification, but not necessarily all of it. There are optional features that may not be implemented in a particular drive model, and a model may have minor deviations from the spec. Also the interface specification may allow broader ranges of characteristics than are documented for any given drive. If you're designing an SMD controller or an SMD drive, you should definitely design to the interface specification, though looking at individual drive model specs is also informative. Unfortunately the later CDC specification for the SMD-E interface (a superset of the SMD interface) does not seem to be available anywhere. I think the ANSI specification covers SMD-E, but I'm not 100% certain.
Re: SMD disk specifications
Thanks Eric, I somehow missed that one. TTFN - Guy > On Dec 13, 2019, at 11:42 AM, Eric Smith wrote: > > On Fri, Dec 13, 2019 at 10:55 AM Guy Sotomayor via cctalk > mailto:cctalk@classiccmp.org>> wrote: > I’ve been trying to find *detailed* specifications (mainly detailed signal > timings) for the SMD disk interface but all I’ve found so far are the > interface specifications for individual disks (CDC, Fujitsu, etc). I’ve > looked in the usual places (bitsavers mostly) and haven’t found the spec > itself. If anyone has any pointers, I’d appreciate it. > > You've seen that the SMD spec (as of March 1981) is on Bitsavers? > pdf/cdc/discs/interface_specs/64712400_SMDCableSpec_Mar81.pdf > > That doesn't cover later enhancements such as SMD-E. >
Re: SMD disk specifications
lördag 14 december 2019 skrev jim stephens via cctalk : > > > On 12/14/2019 1:10 AM, shad 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. I think the name of the division was MPI. CMD was the Cartridge Module Drive aka Phoenix. http://bitsavers.informatik.uni-stuttgart.de/pdf/cdc/discs/CDC_Drive_Models.txt But as far as I know the interface of the SMD drives and CMD drives were identical. At least the Norsk Data ND10 used them both on the same interface in the computer end. /Mattis > 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? > thanks > Jim > >> Andrea >> >> >> >
Re: SMD disk specifications
On 12/14/2019 1:10 AM, shad 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? thanks Jim Andrea
Re: SMD disk specifications
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... Andrea
