I'm using Zynq SOMs (System on a module) that will plug into a "base
board" (with hilrose connectors). It is the base board that will have
the "personality" of the emulator. The baseboard will be fairly simple
(level shifters, a small bit of logic and the drive interface
transceivers). So
Guy,
I agree that accessing data in blockram (synchronous with fixed latency) is
really easier than accessing it from RAM (asynchronous with variable latency).
Anyway I'm weighting the "cost" of additional complexity, which in change would
allow to spare on Zynq cost.
In any case memory access
Good data, thanks! I kind of like the ESDI disks, they're more solid and
reliable than the MFM ones, and to be honest the RQDX3 was not a super
fast disk controller. I wonder if it could do block mode DMA.
I'll keep an eye out for the Sigma, the only thing I wish I had on the
MTI MQD13 would
I also have multiple ESDI controllers, more than one these flavors:
Dilog DQ686
http://www.bitsavers.org/pdf/dilog/2120-0137-1_DQ686_Nov89.pdf
Emulex QD21
http://www.bitsavers.org/pdf/emulex/QD2151002-J_QD21_Jun90.pdf
Sigma SCD-RQD11-EC (There seems to be multiple versions from different
Once upon a time I used an Emulex QD21, but I sold it because the actual
ESDI disks I had were a pain in the butt. Always crashing.
I still have a Webster (quad board) SRQD something.
I think I had a Dilog board also. It's been a while, probably 20 years.
Doug
On 4/18/2022 9:12 PM, Chris Zach
Interesting, what kind of ESDI controllers do you have? They got
advanced features like cache, ordered seeks, and burst mode/block mode DMA?
C
On 4/18/2022 6:09 PM, Douglas Taylor via cctech wrote:
Because of this I'm holding on to my DEC Qbus ESDI controllers!!! You
never know
Doug
Which is more generic.
ESDI, SMD or SCSI.
In my opinion, SCSI is as close are you are going to get to a universal
interface.
As for reading raw data from a drive. The newer the drive, the higher
the bit density and lower the strength of the magnetic fields and hence
the lower the flying
Because of this I'm holding on to my DEC Qbus ESDI controllers!!! You
never know
Doug
On 4/17/2022 4:35 PM, Guy Sotomayor via cctech wrote:
I chose ESDI and SMD fundamentally because the interface is 100%
digital (e.g. the data/clock separator is in the drive itself). So I
don't need to
Guy,
I agree on keeping Linux out of the loop, to allow fast access on head
location, selection.
However, I'm not convinced on the fact that a whole cylinder must be on
blockram to achieve this. Given that ram access is fast (on Zynq with PL
working at 200MHz and HP port at 64bits I'm running
To: t.gard...@computer.org; cctech@classiccmp.org
Subject: Re: idea for a universal disk interface
I think the issue is that you're thinking of somehow emulating the formatted
data. I'm working on just emulating the bit-stream as then it'll work with any
controller and sector/track layout so I
I have proceeded as far as full block diagrams (still have to write all
of the verilog) and basic SW architecture. This is why I've had this
discussion. I've thought about this *a lot* and have gone through
several iterations of what will or will not work given timing constraints.
I have
hello,
there's much discussion about the right method to transfer data in and out.
Of course there are several methods, the right one must be carefully chosen
after some review of all the disk interfaces that must be supported. The idea
of having a copy of the whole disk in RAM is OK, assuming
PM
To: t.gard...@computer.org; cctech@classiccmp.org
Subject: Re: idea for a universal disk interface
I'm looking at what the spec says. ;-) The read command delay from the head
set command is 15us (so I was wrong) but still not a lot of time (that is after
a head set, a read command must be at lea
-Original Message-
From: Guy Sotomayor [mailto:g...@shiresoft.com]
Sent: Friday, April 15, 2022 3:25 PM
To: t.gard...@computer.org; cctech@classiccmp.org
Subject: Re: idea for a universal disk interface
I'm looking at what the spec says. ;-) The read command delay from the head
set
on
a modern drive who cares about some wasted storage
Tom
-Original Message-
From: Guy Sotomayor [mailto:g...@shiresoft.com]
Sent: Friday, April 15, 2022 10:56 AM
To: t.gard...@computer.org; cctech@classiccmp.org
Subject: Re: idea for a universal disk interface
I ran the numbers for
f data on a modern drive who cares about some wasted
storage
Tom
-Original Message-
From: Guy Sotomayor [mailto:g...@shiresoft.com]
Sent: Friday, April 15, 2022 10:56 AM
To: t.gard...@computer.org; cctech@classiccmp.org
Subject: Re: idea for a universal disk interface
s ago
Tom
-Original Message-
From: Guy Sotomayor [mailto:g...@shiresoft.com]
Sent: Wednesday, April 13, 2022 10:02 AM
To: cctech@classiccmp.org
Subject: Re: idea for a universal disk interface
I've had a similar project in the works for a while (mainly for ESDI and SMD).
I think the main issue yo
to buffer a whole cylinder but that was many generations ago
Tom
-Original Message-
From: Guy Sotomayor [mailto:g...@shiresoft.com]
Sent: Wednesday, April 13, 2022 10:02 AM
To: cctech@classiccmp.org
Subject: Re: idea for a universal disk interface
I've had a similar project in the works
...@computer.org; Tom Gardner; General Discussion: On-Topic Posts
Subject: Re: idea for a universal disk interface
> On Apr 13, 2022, at 11:51 AM, Tom Gardner via cctech
> wrote:
>
> There are a few others like ANSI and CalComp but they are probably not worth
> investigating.
>
> On Apr 13, 2022, at 9:45 PM, Fred Cisin via cctech
> wrote:
>
> On Wed, 13 Apr 2022, Paul Koning wrote:
>> Indeed. Though even that is hard for the more exotic formats, if original
>> controllers are unavailable. How would you read, for example, an IBM 1620
>> or CDC 6600 disk pack,
> On Apr 13, 2022, at 8:12 PM, Fred Cisin via cctech
> wrote:
>
> ...
> My mindset is/was still stuck in the disk format conversion realm, of trying
> to get information (hopefully information in the form of files, not just data
> as track images) from alien media.
> And, more often than
> On Apr 13, 2022, at 5:27 PM, Fred Cisin via cctech
> wrote:
>
> On Wed, 13 Apr 2022, shad via cctech wrote:
>> The main board should include a large enough array of bidirectional
>> transceivers, possibly with variable voltage, to support as much interfaces
>> as possible, namely at
> On Apr 13, 2022, at 11:51 AM, Tom Gardner via cctech
> wrote:
>
> There are a few others like ANSI and CalComp but they are probably not worth
> investigating.
>
They are if you’re someone who has a machine using one of these interfaces, or
e.g. the 40-pin “IMI bus”, or whatever else.
On Wed, 13 Apr 2022, Paul Koning wrote:
Indeed. Though even that is hard for the more exotic formats, if
original controllers are unavailable. How would you read, for example,
an IBM 1620 or CDC 6600 disk pack, given that the machine is hard to
find and those that exists may not have the
I'll only mention that there were ICs that could interface to both
MFM/ST506 hard drives as well as floppies (System/3 MFM).
An example would be the SMC HDC9234, "Universal Disk Controller".
Pretty cool chip for the time; has full 24 bit DMA address capability.
But different register/controller
On Wed, 13 Apr 2022, shad via cctech wrote:
The main board should include a large enough array of bidirectional
transceivers, possibly with variable voltage, to support as much interfaces as
possible, namely at least Shugart floppy, ST506 MFM/RLL, ESDI, SMD, IDE, SCSI1,
DEC DSSI, DEC
. . . and, if there is agreement to standardize the connection system for
the "personality modules", then some of the other storage systems could be
implemented, particularly including some of the tape systemmes.
'course, it would be a lot more fun, instead of the 62 pin card edge, to
go
On Wed, 13 Apr 2022, shad via cctech wrote:
The main board should include a large enough array of bidirectional
transceivers, possibly with variable voltage, to support as much
interfaces as possible, namely at least Shugart floppy, ST506 MFM/RLL,
ESDI, SMD, IDE, SCSI1, DEC DSSI, DEC
Interesting idea, there are three broad classes of HDD interfaces:
1. Dumb, that is serial data and parallel control
2. Intelligent parallel
3. Intelligent serial
IMO if you can do dumb interraces then the others follow and given today’s
technology I suspect it is feasible
I've had a similar project in the works for a while (mainly for ESDI and
SMD).
I think the main issue you're going to face is that what you need to do
for something like ESDI or SMD (or any of the bit serial interfaces) is
going to be radically different than something like IDE or SCSI. This
shad said
> Hello,
> I'm a decent collector of big iron, aka mini computers, mainly DEC and DG.
> I'm often facing common problems with storage devices, magnetic discs and
> tapes are a little prone to give headaches after years, and replacement
> drives/media in case of a severe failure are
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