13 Mar
2016
13 Mar
'16
1:28 p.m.
Does anyone recall an Olivetti ST506-interface drive with a colossal 3MB
capacity? Apparently a full-height 5.25" unit with 4 heads and two platters.
I'm just curious; I always thought that capacities either equaled or
surpassed the 5MB of Seagate's ST506 after they introduced it, so I was a
bit surprised to hear of a drive with < 5MB.
For context, Acorn apparently used them during development of their
external Winchester units for BBC micros (Acorn SASI board, Adaptec
SASI-ST506 bridge, ST506 drive). Production units that I'm aware of had
either a 10MB or 30MB drive fitted (BASF typically, I think). We're talking
1983, or maybe late '82, so considerably after the introduction of the
original Seagate drive.
The only Olivetti drives I'm finding mention of are a 10MB single-platter
drive and a 20MB dual-platter drive. Acorn had close ties with Olivetti, of
course, so I did wonder if Acorn acquired some pre-production drives - but
it seems like a bit of a leap to go from a 3MB dual-platter prototype to a
20MB one.
cheers
Jules
13 Mar
13 Mar
2:15 p.m.
On 03/13/2016 10:28 AM, Jules Richardson wrote:
Does anyone recall an Olivetti ST506-interface drive with a colossal
3MB capacity? Apparently a full-height 5.25" unit with 4 heads and
two platters.
I'm just curious; I always thought that capacities either equaled or
surpassed the 5MB of Seagate's ST506 after they introduced it, so I
was a bit surprised to hear of a drive with < 5MB.
Hard drives smaller than 5MB were not unusual. For example, the Rodime
RO-101 was only 3MB.
My list shows Olivetti-branded drives starting at 10MB forever. So
probably someone else's drive.
--Chuck
3:38 p.m.
On 03/13/2016 01:15 PM, Chuck Guzis wrote:
Hard drives smaller than 5MB were not unusual. For
example, the Rodime
RO-101 was only 3MB.
Interesting... I've had 'real' ST506's before, but I don't think
I've ever
seen or heard of anything less than that (in a 5.25" f/f)
My list shows Olivetti-branded drives starting at 10MB
forever. So
probably someone else's drive.
Right, they did a 10MB and 20MB, but I've not heard of anything else...
These 3MB ones were definitely Olivetti - this was from an ex-Acorn
employee who worked on the drive project. 3MB to 20MB seems a big jump -
but it makes me wonder if they were working with drives that had three
surfaces masked out due to manufacturing defects; one surface would be 5MB,
and going from 3MB per surface in a pre-production drive to 5MB in the end
product wouldn't be such of a leap.
J.
4:12 p.m.
On 03/13/2016 12:38 PM, Jules Richardson wrote:
These 3MB ones were definitely Olivetti - this was
from an ex-Acorn
employee who worked on the drive project. 3MB to 20MB seems a big
jump - but it makes me wonder if they were working with drives that
had three surfaces masked out due to manufacturing defects; one
surface would be 5MB, and going from 3MB per surface in a
pre-production drive to 5MB in
Do you have a part number for the Olivetti drive? I think that taking a
10MB drive and downgrading it to a 3MB one wouldn't be a paying venture.
--Chuck
5:34 p.m.
On 03/13/2016 03:12 PM, Chuck Guzis wrote:
On 03/13/2016 12:38 PM, Jules Richardson wrote:
No, unfortunately not, and the official service manual only mentions 10MB
and 30MB drives (neither of which were Olivetti parts).
These 3MB ones were definitely Olivetti - this
was from an ex-Acorn
employee who worked on the drive project. 3MB to 20MB seems a big
jump - but it makes me wonder if they were working with drives that
had three surfaces masked out due to manufacturing defects; one
surface would be 5MB, and going from 3MB per surface in a
pre-production drive to 5MB in
Do you have a part number for the Olivetti drive? I think that taking a
10MB drive and downgrading it to a 3MB one wouldn't be a paying venture.
AIUI, Olivetti only shipped these 3MB drives to Acorn while they were
testing their Winchester unit - Acorn never used them elsewhere. I am
curious if they ever saw production though.
Assuming for the moment that there were completely disabled surfaces
involved due to too many defects (i.e. that this was a 2-platter drive with
only one or maybe two active surfaces and the rest mapped out by the drive
firmware), do you know how common a practice that was in the early days of
ST506/412-type drives?
I've heard various stories of it happening much later with more modern IDE
drives in the multi-GB range (e.g. a 20GB drive might be a 40GB
single-platter drive with one surface that had completely failed QC), but I
don't know if it was ever done in the ST506/412 era.
Jules
6:02 p.m.
On Sun, Mar 13, 2016 at 3:34 PM, Jules Richardson
<jules.richardson99 at gmail.com> wrote:
Assuming for the moment that there were completely
disabled surfaces
involved due to too many defects (i.e. that this was a 2-platter drive with
only one or maybe two active surfaces and the rest mapped out by the drive
firmware), do you know how common a practice that was in the early days of
ST506/412-type drives?
I've heard various stories of it happening much later with more modern IDE
drives in the multi-GB range (e.g. a 20GB drive might be a 40GB
single-platter drive with one surface that had completely failed QC), but I
don't know if it was ever done in the ST506/412 era.
Often when components and assemblies are sold in a down-spec
configuration, it isn't because anything failed test, but rather
because they didn't take the time to do the testing on that portion.
Testing a product is a significant part of the manufacturing cost, so
there's actually significant cost savings associated with only testing
a portion. This is often the case with memory chips and multicore
processor chips; I don't know that it was done with hard drives, but
manufacturing test time for hard drives was definitely expensive.
On the other hand, I'm told that in mass production it is extremely
uncommon for a side of a disk platter to have more than the allowable
number of defects, so it seems more likely that a downspec hard drive
would simply have fewer platters (and heads, etc.) installed, rather
than having some disabled for excessive defects, or some untested.
8:32 p.m.
On 03/13/2016 03:02 PM, Eric Smith wrote:
On the other hand, I'm told that in mass
production it is extremely
uncommon for a side of a disk platter to have more than the
allowable number of defects, so it seems more likely that a downspec
hard drive would simply have fewer platters (and heads, etc.)
installed, rather than having some disabled for excessive defects, or
some untested.
On the other hand, there were a few small-drive manufacturers back in
the day. I don't think that Disctron/Otari ever made it past 20MB--but
they certainly had a bunch of single-digit MB drives, including a 2 MB one.
It seems that 5.25" hard drive startups came in at least two phases.
Some, like Memorex or BASF gave up after a run of low-capacity drives;
others started up at the 10MB and up category. I suspect this is due to
a certain extent with the economic downturn around 1980. (Remember the
days of 18 percent morgages?) Money was tight and inflation was high.
The "DRAM war" didn't help much either. (16K DRAMs were a very
"hot"
property, often in both senses of being in demand and being purloined).
Good times...
--Chuck
6:13 p.m.
Is that "3MB" FORMATTED, or UNFORMATTED capacity?
"10MB" (ST412) was 12MB unformatted, with 306 cylinders and 4 heads.
"5MB" (ST406) was 6MB unformatted, with 306 cylinders and 2 heads. or was
it (St506?) 153 cylinders with 4 heads?
In any case, using half as many heads/surfaces would create an "ST503"
drive. about 2.5M formatted capacity.
9:17 p.m.
I don't recall how many heads a ST506 had. I have one on my NC4000,
home brew, machine. I recall picking the drives up at garage sales because
DOS no longer supported them, only being 5Meg.
Next time I at my storage, I can being my machine home and power it up.
I suspect it has the setup information in my source code.
I used an old XT HD controller card for the hard drive and a XT floppy card
for the floppy. I disabled the EPROM on the HD card because it was
useless for the NC4000.
The M20 used the 11Meg ( I guess formatted 10 Meg ) drives. I used a
ST251 because it had the same number of heads (6) and RPM speed as
the Olivetti drive used. It had more cylinders but that wasn't an issue.
Dwight
________________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Fred Cisin <cisin at
xenosoft.com>
Sent: Sunday, March 13, 2016 3:13 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Olivetti 3MB ST506-interface drive?
Is that "3MB" FORMATTED, or UNFORMATTED capacity?
"10MB" (ST412) was 12MB unformatted, with 306 cylinders and 4 heads.
"5MB" (ST406) was 6MB unformatted, with 306 cylinders and 2 heads. or was
it (St506?) 153 cylinders with 4 heads?
In any case, using half as many heads/surfaces would create an "ST503"
drive. about 2.5M formatted capacity.
10:39 p.m.
On Mon, 14 Mar 2016, dwight wrote:
I don't recall how many heads a ST506 had. I have
one on my NC4000,
home brew, machine. I recall picking the drives up at garage sales because
DOS no longer supported them, only being 5Meg.
ftp://ftp.seagate.com/pub/techsuppt/mfm/st506.txt
ftp://ftp.seagate.com/pub/techsuppt/mfm/st406.txt
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