How standard, in dimensions, are 3.5 drives?

[khaz]

more specifically overall length, mounting holes, data and power cable position, etc.

?

[1024MAK]

Excluding the really early drives, and excluding laptop drives, the mounting holes are fairly standard.
Everything else, however varies. The front bezel of most drives are one of three standard-ish heights (excluding laptop drives).
Length varies, but there is a maximum (I've never bothered to measure, as every one I have fits in the space where a previous 3.5 inch drive was).

Mark

[khaz]

Thanks. I was able to find some documentation online here ftp://ftp.seagate.com/pub/sff/SFF-8300.PDF . The dimensions are fairly standardized but the connectors are all over the place sadly. I'm surprised by the three different heights though, I've never seen the smaller nor bigger one, and they aren't multiples of each other so don't stack properly in a rack. I won't bother with them any how.

[Bryce]

Excluding the really early drives, and excluding laptop drives, the mounting holes are fairly standard.
Everything else, however varies. The front bezel of most drives are one of three standard-ish heights (excluding laptop drives).
Length varies, but there is a maximum (I've never bothered to measure, as every one I have fits in the space where a previous 3.5 inch drive was).

Mark

Yes, as with so many other things in electronics, they said "We need a standard!"... so the industry came up with 20 of them

Bryce.

[khaz]

Yes, as with so many other things in electronics, they said "We need a standard!"... so the industry came up with 20 of them

Bryce.

Obligatory xkcd

[1024MAK]

Thanks. I was able to find some documentation online here ftp://ftp.seagate.com/pub/sff/SFF-8300.PDF . The dimensions are fairly standardized but the connectors are all over the place sadly. I'm surprised by the three different heights though, I've never seen the smaller nor bigger one, and they aren't multiples of each other so don't stack properly in a rack. I won't bother with them any how.

Ah, I was not aware of that document. Instead, I have read various manufacturer data sheets over the years.
The three heights relates to how the industry has miniaturised over the years. The largest size was used in old computers as the half-height 5.25" was suppose to be discontinued.
The middle size is very common, as you expect.
The smaller size was fitted to the most recent computers that had floppy drives, but you cannot often tell from the outside. Also on some laptops etc.

Mark

[CloudStrife]

The two standard I know about disk drive bay are EIA-740 and EIA-741.
And like every standard... You need to pay to have them... grrrr !
(I think I have them somewhere, but not sure...)

[PulkoMandy]

@CloudStrife: the ECMA standards are free. Only the american stuff you have to pay for (and ISO, in Swiss Francs).


The thicker 3.5" drives are found for example in Atari ST and Thomson computers. But it is no problem to fit the normal version there (if you can live with the small space above)


Original drive in TO8D:



Replaced with thiner PC drive:

[CloudStrife]

@CloudStrife: the ECMA standards are free. Only the american stuff you have to pay for (and ISO, in Swiss Francs).

Not only american standard and ISO...
Take a look to the AFNOR standards (French standard organization)
And some are even mandatory ! Like the NF C 15-100, it's mandatory that you electrical installation follow it and it cost more than 350€ without tax...

(But yes "like nearly" is more exact...)

[MacDeath]

thats a sweet TO8D you got there...

How fun that there is actually a sound output... but no proper sound chip... 

[PulkoMandy]

There is a 6-bit DAC in there! Better samples than on Amstrad CPC, but it keeps the CPU busy to feed it. The "music and game" expansion for Thomson machines should have been called "music OR games".