On 07/03/2020 10:00, Martin Gregorie wrote:
> On Sat, 07 Mar 2020 08:39:47 +0000, Jan Panteltje wrote:
>
>> In the eighties you had IBM drives of maybe it was 10GB? tha thad a
>> mechanical lever likething on the side, it ws connected to teh head
>> movement,
>> If the head positioning got stuck or something you could move that lever
>> and the thing would work again....
>> So, anyways, sorry about that.
>>
> Wash your mouth out! Back in the '70s IBM was the Great Satan, with
> predatory salesmen and SEs, all in the dark suit, white shirt and blue
> tie company uniform and many brainwashed to the point of disbelieving
> that anybody other than IBM even made computers. Yes, I did meet, and
> worked with, a guy who had bought (gasp!) 3rd party disk drives and
> consequently had a posse of IBMers show up and harangue his management to
> try and get him fired.
>
> Anyway - when I started work with ICL in the late 60s, our biggest disks
> were 8 MB. The drives were desk height, about 50cm X 80cm on top. They
> used removable cartridges with a stack of 10 recording surfaces, all 14"
> diameter. Spun at 2800 rpm and had an average access time of around 135
> mS.
>
> By 1973 they'd grown to 60MB capacity and 20 recording surfaces, still
> using 14" platters, spun a bit faster (3600 rpm IIRC) and access time was
> down a little to under 100 mS. George 3 used a clever head movement
> scheduler that tripled the effective access rate.
>
> Biggest drive I ever saw back in the day was 400MB, still using 14"
> removable cartridges, but the number of recording surfaces had more than
> doubled.
>
> FWIW, I first saw a microcomputer in 1976/77 at The Computer Store in NYC
> at 5th and 35th, which sold SWTPC and Imsai systems, No disks of any sort
> - they weren't around much before the early late 70s when Shugart 5.25"
> floppies started to appear and then in the early 80s 5" hard drives with
> (gasp!) 5MB or even 10MB capacity started to appear.
>
>
8" floppies predated the 5 1/4" for some CP/M style machines

My first computer had twin 5.25 but IIRC others used 8"


--
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
windows of my apartment. (I live on the twenty-first floor.) "

Alan Sokal

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