30 Nov
2003
30 Nov
'03
3:12 a.m.
On Fri, 28 Nov 2003, Bob Shannon wrote:
Mike Gemeny wrote:
Ok, you can try to support 'classic' HP disk drives, and pay for
filters, etc. Until your media
wears out, or your heads need replacement. These are all life-limited
components.
But at some point the original disk hardware will no longer be practical
to support. That time is
fast approaching for all but CS/80 series disks, and they have a
lifetime limit also.
So at some point disk drive emulation will be the only option. Its
important to develop these
emulations NOW, while there are still some working 'real' disk drives to
use as a reference for
the development of the emulation.
As for appearances, emulated drives can be built into the chassis of
non-functional drives
for a museum-quality appearance. But if you shun disk hardware
emulation now it may not
be as easy or practical to implement after the real hardware is gone.
Personally, I've already bypassed emulating real HP disk drives and have
developed my own
disk controller for HP 1000's (not supported by RTE). RTE-IVB is such
an ugly O/S I have
no interest in running it, so compatibility with actual HP hardware was
not as important as was
making the device driver development and interface hardware as simple as
possible.
Now I run modern ATA (IDE) disk drives on my HP 1000's. This is just so
much more
practical than running real drives (including the real CS/80 disks I have).
You might want to rethink your objections to disk hardware emulation.
I'd be happy to help
adapt my existing emulation scheme to include compatibility with 'real'
HP disk drives.
Another possibility would be to produce a kit-form of my existing ATA
disk controller for
HP collectors, but this would only be supported by HP-IL/OS, and not by
RTE (unless
someone wants to write an RTE driver for my controller!).
Another possibility is to emulate only the actual drive in hardware. That is a
simple FPGA +ATA drive based device could emulate the magnetics and head
positioning interface of the original drive. Then you could use the same disk
controller and the system software would see no changes.
Since there is so much excess storage available in current ATA drives, plus
the original data rates are quite slow relative to a FPGA serial data recovery
clock, an inefficient but simple to implement sector data record and playback
data encoding scheme could be used, for example by storing ~5 bits per
original data bit, the time between data transitions could recorded and
replayed (with possible emulation of magnetic bit timing aberrations to undo
the effects of write-precomp)
(I think Eric Smith gave me this idea...)
Peter Wallace
it's a
museum!!! Emulate hardware for display?
I agree, I’m running two 2883s on Access under simulation. I run a single
7900 on the TSB E version, and a single 2883 on the F version.