Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[Liam Proven via cctech]

On 2 October 2017 at 14:22, Jules Richardson via cctech
 wrote:
>
> Does anyone know why IDE/ATA even came about? I mean, why SCSI wasn't used?

Sure, yes.

It was cheap.

SCSI was expensive, and that was aside from any licensing issues. A
working SCSI bus effectively means 2 smart devices, communicating over
a defined _shared_ channel.

ST-506 was simple, dumb and cheap... like the IBM PC.

https://en.wikipedia.org/wiki/ST-506

As drive capacities grew, ESDI came along.

https://en.wikipedia.org/wiki/Enhanced_Small_Disk_Interface

I believe partly due to timing issues, some of the "smarts" of the
controller were moved from the disk controller card onto the drive
electronics -- but the cables were kept the same. (2 cables, 34 pin
control cable, with 3 connectors, shared by up to 2 drives; plus 2×
20-pin data cables, one per drive.)

Then most of the controller electronics were moved onto the drive, so
that no "disk controller" was needed any more -- the drive contained
the controller. Now the 2 cables were consolidated into a single
40-way cable, one end of which connected to the motherboard and the AT
bus. (The 16-bit bus from the IBM PC-AT, so called to distinguish it
from the 8-bit bus of the IBM PC.) The cable had 2 connectors for 2
drives, but they had to be jumpered to tell them which was master and
which was slave, and not all combinations worked, not in the early
days.

IDE was mainly an x86 PC thing at first. Later, the 2nd-generation
Acorn ARM machines had it, and the Commodore Amiga 1200 had an
on-board interface for a 2.5" notebook-sized IDE drive. Later still
Apple adopted it for its cheap home machines, the Performa PowerMacs.
In the early ones, I think the hard disk was IDE and the CD drive was
SCSI, and they still included a SCSI bus.

Around 1994 or so, I ordered some machines from Elonex intended to run
Windows NT 3.1. There was a substantial saving on ordering IDE models
instead of SCSI-equipped ones.

What I didn't know is that these had 540MB drives, and the IDE
definition only allowed for 1024 cylinders, 63 sectors per track and
16 heads -- meaning 528MB max.

These were not IDE drives, they were EIDE drives. Enhanced IDE.

NT 3.1 didn't understand EIDE. It couldn't do Logical Block
Addressing, only Cyl/Head/Track.

So to NT, the last 12MB of these drives was all bad blocks.


Returns and much argument followed. That got me a mention in
Microscope magazine, which later got me an interview at Dennis
Publishing and a job on PC Pro magazine. 21 years later, I'm a tech
writer at SUSE in Prague. Funny how life turns out.

Later, other limits came in at ~8GB, then at ~128GB, then a rather
different one at 2TB.

http://philipstorr.id.au/pcbook/book4/hdlimit.htm



-- 
Liam Proven • Profile: https://about.me/liamproven
Email: lpro...@cix.co.uk • Google Mail/Talk/Plus: lpro...@gmail.com
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Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[Warner Losh via cctech]

On Mon, Oct 2, 2017 at 9:12 AM, Jon Elson via cctech 
wrote:

> On 10/02/2017 08:29 AM, allison via cctech wrote:
>
>>
>>
>> It was price...  ATA-IDE was cheaper and PC industry was working hard to
>> push the price down.
>> SCSI always remained more costly.
>>
>> Yes.  I think there were royalties to pay for a true SCSI drive. Anyway,
> there was a VERY significant price
> difference between early IDE and SCSI drives.  Several hundred $ for a
> similar capacity drive.
>

The difference has persisted to this day. SCSI tags are deeper than NCQ for
ATA. The error reporting from SCSI is much richer than you get from ATA. In
general, reliability is better for SAS drives than for SATA drives, and the
performance variations you see in SATA have a higher magnitude than the SAS
drives.

ATA was always meant to get bits to the user at a lower cost w/o solving
all the hard problems SCSI tried to solve.

Warner

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[Alan Perry via cctech]

On 10/2/17 11:34 AM, Chuck Guzis via cctech wrote:

On 10/02/2017 10:03 AM, Alan Perry via cctech wrote:


Here is a complete quote from the minutes:
"Jim McGrath of Quantum defined his company's interest as being
primarily in the ability to embed SCSI into a drive without there being
a physical SCSI bus present. He described some problems of this
environment, with references to the PC AT bus in particular. Jim
believes that the greatest benefit of the CAM will come from a "severe
pruning of SCSI functionality in order to meet the goal of a precise,
simple, software interface."

While ATA was codified by the CAM working group, one should not be under
the impression that CAM was limited to any particular physical interface.

CAM stands for "Common Access Method" and is applicable to a number of
physical interfaces, including SCSI.   Future Domain, for example,
patterned their drivers along CAM conventions, using CCB (CAM control
blocks).  Adaptec, on the other hand, perferred ASPI.  Of the two, CAM
is far more flexible and varied.  After Adaptec acquired FD, they
provided a "middle" driver to convert ASPI calls to CAM.

Just saying...

FWIW I included the full quote from the minutes as elaboration on my 
summary since someone asked a question related to it.


I used to work on SATA and wrote a brief history of the evolution of 
disk interfaces to present to new college grad hires. When someone else 
brought the topic of the origin of the phrases, it got me wondering 
specifically who came up with "AT Attachment", partly since I indirectly 
knew Bob Snively.


alan

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[Chuck Guzis via cctech]

On 10/02/2017 10:03 AM, Alan Perry via cctech wrote:

> Here is a complete quote from the minutes:
> "Jim McGrath of Quantum defined his company's interest as being
> primarily in the ability to embed SCSI into a drive without there being
> a physical SCSI bus present. He described some problems of this
> environment, with references to the PC AT bus in particular. Jim
> believes that the greatest benefit of the CAM will come from a "severe
> pruning of SCSI functionality in order to meet the goal of a precise,
> simple, software interface."

While ATA was codified by the CAM working group, one should not be under
the impression that CAM was limited to any particular physical interface.

CAM stands for "Common Access Method" and is applicable to a number of
physical interfaces, including SCSI.   Future Domain, for example,
patterned their drivers along CAM conventions, using CCB (CAM control
blocks).  Adaptec, on the other hand, perferred ASPI.  Of the two, CAM
is far more flexible and varied.  After Adaptec acquired FD, they
provided a "middle" driver to convert ASPI calls to CAM.

Just saying...

--Chuck

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[Alan Perry via cctech]

On 10/2/17 5:22 AM, Jules Richardson via cctech wrote:

On 10/02/2017 01:46 AM, Alan Perry via cctech wrote:
There was a call to form the CAM (Common Access Method) Committee of 
X3T9.2

(SCSI-2) on 30 Sept 1988 and they first met on 19 Oct 1988. The primary
goal was to come up with a SCSI subset to facilitate it support in 
multiple

OSs and BIOS on PCs. At the first meeting, two items mentioned in the
minutes seem relevant. 1. Jim McGrath of Quantum was interested in
embedding SCSI in the drive without a physical SCSI bus and described
problems with reference to the PC/AT.


Does anyone know why IDE/ATA even came about? I mean, why SCSI wasn't 
used? It would have been an established standard by then, the drive 
complexity seems comparable to IDE/ATA (i.e. intelligent commands over 
a parallel bus), and SCSI controllers can be extremely simple - just a 
handful of LS logic ICs - unless you want to add loads of command 
queuing and such (again, comparable to IDE)


Did it simply come down to pressure from vendors, wanting to 
distinguish between expensive workstation-class drives and something 
cheaper which could be associated with the lowly PC?


Here is a complete quote from the minutes:
"Jim McGrath of Quantum defined his company's interest as being 
primarily in the ability to embed SCSI into a drive without there being 
a physical SCSI bus present. He described some problems of this 
environment, with references to the PC AT bus in particular. Jim 
believes that the greatest benefit of the CAM will come from a "severe 
pruning of SCSI functionality in order to meet the goal of a precise, 
simple, software interface."


alan




cheers

Jules

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[Jon Elson via cctech]

On 10/02/2017 08:29 AM, allison via cctech wrote:



It was price...  ATA-IDE was cheaper and PC industry was 
working hard to push the price down.

SCSI always remained more costly.

Yes.  I think there were royalties to pay for a true SCSI 
drive. Anyway, there was a VERY significant price
difference between early IDE and SCSI drives.  Several 
hundred $ for a similar capacity drive.


Jon

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[allison via cctech]

On 10/2/17 10:13 AM, Jules Richardson via cctech wrote:

On 10/02/2017 08:29 AM, allison via cctech wrote:



On 10/2/17 8:22 AM, Jules Richardson via cctech wrote:

On 10/02/2017 01:46 AM, Alan Perry via cctech wrote:
There was a call to form the CAM (Common Access Method) Committee 
of X3T9.2
(SCSI-2) on 30 Sept 1988 and they first met on 19 Oct 1988. The 
primary
goal was to come up with a SCSI subset to facilitate it support in 
multiple

OSs and BIOS on PCs. At the first meeting, two items mentioned in the
minutes seem relevant. 1. Jim McGrath of Quantum was interested in
embedding SCSI in the drive without a physical SCSI bus and described
problems with reference to the PC/AT.


So in effect the IDE was a minimal interface that would interface to the
computer bus
with no more than buffering.


True, I suppose the command structure was more complex with SCSI. It's 
a shame though, it would have been nice if SCSI had been the PC 
standard, what with the large number of devices available, more 
flexibility, and performance potential.


It was/is widely used in PCs.  It put Adaptec on the map.  Servers and 
high end systems

commonly used it especially for early shadow and RAID systems.


Early SCSI disks
were MFM drives with Adaptec or Xybec host boards (SCSI to MFM, local 
cpu

was Z80 on the adaptor).


Xebec... but yeah, and I forgot that they used a Z80 (I was thinking 
it was some Intel 80xx thing). 

Later versions of bridge boards had the 8088 or 80188 16bitter.

I don't know if Xebec actually made a SCSI one, I think they may all 
have been SASI (at least the ones that I've used). I remember there 
was a little schematic in the back of the manual for a suitable 
controller.


Some were SASI and later firmware was SCSI...  Only difference as I had 
both.


Adaptec, Emulex and OMTI all made similar bridge boards... and there 
were probably others, too.



Yes, them too.

Oddly the first VAX to use SCSI or SCSI like was uVAX-2000 as the extra 
box with TK50 Tape

used that.

Allison

cheers

Jules

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[Jules Richardson via cctech]

On 10/02/2017 08:29 AM, allison via cctech wrote:



On 10/2/17 8:22 AM, Jules Richardson via cctech wrote:

On 10/02/2017 01:46 AM, Alan Perry via cctech wrote:

There was a call to form the CAM (Common Access Method) Committee of X3T9.2
(SCSI-2) on 30 Sept 1988 and they first met on 19 Oct 1988. The primary
goal was to come up with a SCSI subset to facilitate it support in multiple
OSs and BIOS on PCs. At the first meeting, two items mentioned in the
minutes seem relevant. 1. Jim McGrath of Quantum was interested in
embedding SCSI in the drive without a physical SCSI bus and described
problems with reference to the PC/AT.


So in effect the IDE was a minimal interface that would interface to the
computer bus
with no more than buffering.


True, I suppose the command structure was more complex with SCSI. It's a 
shame though, it would have been nice if SCSI had been the PC standard, 
what with the large number of devices available, more flexibility, and 
performance potential.



Early SCSI disks
were MFM drives with Adaptec or Xybec host boards (SCSI to MFM, local cpu
was Z80 on the adaptor).


Xebec... but yeah, and I forgot that they used a Z80 (I was thinking it was 
some Intel 80xx thing). I don't know if Xebec actually made a SCSI one, I 
think they may all have been SASI (at least the ones that I've used). I 
remember there was a little schematic in the back of the manual for a 
suitable controller.


Adaptec, Emulex and OMTI all made similar bridge boards... and there were 
probably others, too.


cheers

Jules

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[allison via cctech]

On 10/2/17 9:40 AM, william degnan wrote:



ATA-IDE and SCSI (OK SASI) are about the same age but had
different adoption and growth rates.

Earliest SASI/SCSI was AmproLB+ and Visual 1050 with adaptor.  I
have both with hard disks.
FYI the Z80 powered AMPROLB+ was 1984 introduction.


The Commodore D9060/D9090 pre-dates these and was a SASI derivative, 
right?  Not that it matters which was first, but just wanted to 
mention the CBM hard drive too. I have worked with the Visual and CBM 
drives, but never seen the AMPRO.



Hi Bill,

I used those as I knew the dates well having them since new.

Ampro was a basic 64K Z80 system with mini (5.25) or micro(3.5) inch 
floppy interface and if purchased the 5380 parallel/SCSI/SASI adaptor 
chip.  With it you could use the varios boards (Adaptec or Xybec) and 
the Shugart 20mb SASI drive with the existing software supplied.  I 
modded the BIOS to adapt it for a Fujitsu 45mb 3.5" SCSI drive a few 
years later. and it would work with most current generation SCSI-1 
drives save for partitioning and initializing.


The visual was actually older and used TTL to create SASI (scsi look 
alike) bus and the same adaptors

and drives to complete the hard disk side like the Ampro.

I still feel the SCSI bus was inspired by IEE488 (GPIB).

In the systems world my first SCSI on VAX was microVAX ba123 (uVAXIIgpx) 
with CMD controller
and a RD54(MFM 150mb) on an Adaptec Controller and later replaced with 3 
RZ56s (drive with SCSI internal).


Memries of the first SASI/SCSI was 33 years ago for Me, and VAX SCSI was 
1995 as that's when I got

the CMD controller.

Allison

Bill

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[william degnan via cctech]

>
>
> ATA-IDE and SCSI (OK SASI) are about the same age but had different
> adoption and growth rates.
>
> Earliest SASI/SCSI was AmproLB+ and Visual 1050 with adaptor.  I have both
> with hard disks.
> FYI the Z80 powered AMPROLB+ was 1984 introduction.


The Commodore D9060/D9090 pre-dates these and was a SASI derivative,
right?  Not that it matters which was first, but just wanted to mention the
CBM hard drive too.  I have worked with the Visual and CBM drives, but
never seen the AMPRO.

Bill

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[allison via cctech]

On 10/2/17 8:22 AM, Jules Richardson via cctech wrote:

On 10/02/2017 01:46 AM, Alan Perry via cctech wrote:
There was a call to form the CAM (Common Access Method) Committee of 
X3T9.2

(SCSI-2) on 30 Sept 1988 and they first met on 19 Oct 1988. The primary
goal was to come up with a SCSI subset to facilitate it support in 
multiple

OSs and BIOS on PCs. At the first meeting, two items mentioned in the
minutes seem relevant. 1. Jim McGrath of Quantum was interested in
embedding SCSI in the drive without a physical SCSI bus and described
problems with reference to the PC/AT.


Does anyone know why IDE/ATA even came about? I mean, why SCSI wasn't 
used? It would have been an established standard by then, the drive 
complexity seems comparable to IDE/ATA (i.e. intelligent commands over 
a parallel bus), and SCSI controllers can be extremely simple - just a 
handful of LS logic ICs - unless you want to add loads of command 
queuing and such (again, comparable to IDE)


Roughly the same at the complexity level but SCSI was more costly as it 
was a defined bus
and did not include the actual device level hardware which SCSI disks 
needed same as IDE.
The ya but was to get SCSI to go faster it needed a complex chip in the 
computer (anyone

remember the NCR 5380 and its kin...) that was costly and PITA to program.

So in effect the IDE was a minimal interface that would interface to the 
computer bus
with no more than buffering.  SCSI required translation from PC buses to 
SCSI BUS and then
from SCSI to IDE(essentially the same electronics with SCSI bus 
interface).  IDE was always a
register interface where SCSI was a protocol that needed a smarter 
target.  Early SCSI disks
were MFM drives with Adaptec or Xybec host boards (SCSI to MFM, local 
cpu was Z80 on the adaptor).


ATA-IDE and SCSI (OK SASI) are about the same age but had different 
adoption and growth rates.


Earliest SASI/SCSI was AmproLB+ and Visual 1050 with adaptor.  I have 
both with hard disks.

FYI the Z80 powered AMPROLB+ was 1984 introduction.
Did it simply come down to pressure from vendors, wanting to 
distinguish between expensive workstation-class drives and something 
cheaper which could be associated with the lowly PC?


It was price...  ATA-IDE was cheaper and PC industry was working hard to 
push the price down.

SCSI always remained more costly.

Allison

cheers

Jules

Re: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

[Alan Perry via cctech]

On 10/1/17 1:22 PM, Fred Cisin via cctech wrote:

On Sun, 1 Oct 2017, Tom Gardner via cctalk wrote:
I've looked for but cannot find any WD or Compaq documents publically 
using IDE to describe what ultimately issued as ATA-1.  My search 
included various Compaq maintenance manuals.


Thank you very much for doing those searches!
My first encounter with one was in a Compaq, without having previously 
heard any mention that they were going to do anything like that.  And 
no prior mention of "IDE" NOR "ATA".

It was a surprise, but seemed to make sense.

So, the PR and naming bodies of the relevant companies let it go into 
use without massive prior bragging!  I hadn't been paying close 
attention to CDC nor Connor, but I seemed to have missed whatever WD 
or Compaq had advertised about it at Comdex.


And then, later, I heard "IDE", before I had heard "ATA", but that was 
presumably just due to the circles that I dealt with.



The earliest public use of ATA and AT attachment that I can find is 
March 1969 at the CAM committee 

Would that be 1989?

My recollection (possibly flawed) is WD tried to have the responsible 
committee change the name to IDE and failed.


especially interesting
Standards committees are always being pressured by individual 
companies to use the specific structures and terminologies of those 
companies.


I do have a confidential WD document from 1965 which does use the 
term IDE for "Integrated Drive Electronics" referring to their chips, 
a drive built with these chips was called an "Integrated Drive" or an 
ID.

Would that be 1985?

The CAM and ANSI committees have since March 1969 defined ATA == AT 

Would that be 1989?
(In 1969, it would certainly NOT be a reference to the IBM PC/AT (5170)!)


I did my own searching.

There was a call to form the CAM (Common Access Method) Committee of 
X3T9.2 (SCSI-2) on 30 Sept 1988 and they first met on 19 Oct 1988. The 
primary goal was to come up with a SCSI subset to facilitate it support 
in multiple OSs and BIOS on PCs. At the first meeting, two items 
mentioned in the minutes seem relevant. 1. Jim McGrath of Quantum was 
interested in embedding SCSI in the drive without a physical SCSI bus 
and described problems with reference to the PC/AT. 2. Bob Snively of 
Adaptec is described as indicating that everyone at the meeting has the 
problem of "attaching to systems" and this aspect of the committee's 
work was described as "attachment problems".


Unfortunately, I can't find CAM Committee minutes after that first 
meeting. If anyone here is a member of ANSI Technical Committee T13, 
perhaps they can check to see if the minutes or early drafts of ATA 
documents hidden away in the member only areas of the web site.


The next thing that I found was June 1989 X3T9.2 minutes indicating the 
the CAM Committee had almost completed the "ATA document". It mentioned 
two CAM Committee meetings (10 May 1989 and 8 June 1989), but was not 
clear on at which one of those meetings it was reported on the status of 
the ATA document. I read somewhere unofficial that the first draft of 
the ATA document came out in Mar 1989.


alan