Re: Upcoming project: virtual hard drive for //c and IIgs

[IUnknown <stevementzer@gmail.com>]

On Apr 26, 10:30 am, Steven Hirsch <snhir...@gmail.com> wrote:
> Peltier Cedric wrote:
> >> There are plenty of examples out there showing how such a driver might
> >> be done for Linux.  Poke around for sio2pc (Atari) and Drivewire
> >> (Tandy CoCo).
>
> > Maybe a driver for the smartbus is possible under linux, but I don't
> > know if we could sample reliably a 250KHz serial line through even
> > modern PC I/O under a multitasking environnement (I will give it a try)
> > without a dedicated hardware. From my point of view, using such
> > dedicated hardware on a modern system look pointless for the task,
> > better to do a stand alone system from scratch interfacing the smartbus
> > to IDE or SD. I hope I exposed constraints clearly.
>
> I don't know enough about the smartbus protocol to speak authoritatively, but
> the parallel port hardware on more recent systems should be capable of 1Mhz.
> operation.  How tight are the timing margins?  Where can I find a timing
> diagram for the bus?
>
> If it could be done with a small amount of logic or FPGA, that would still be
> of interest to me.
>
> Steve

I have always wondered about a 'virtual hard drive' project like
this.....  Using some sort of serial connection.

The IDE/CF adapters for the IIgs devices are cool, but they are far
too expensive for the hobbyist.

Serial ports can be added to any PC or MAC with a $10 USB->DB9
adapter. The IIgs has built-in serial ports, but I don't think it is
possible to 'boot' from one.....

It wonder if it would be possible to throw together an *extremely*
simple card for the IIgs that hooked into the boot sequence enough to
control a simple onboard UART....   and talked to a 'host' at the
other end of the cable...

Even at 56kbps operation, which should be pretty easy to obtain... it
would be plenty fast for most operations...  Sure, you could use a
parallel connection, but I wonder if the extra wires and component
costs would be worth the speed advantage.

The software to drive it could be written in a cross-platform language
like java or C#/.NET ... the hard part would be interfacing with the
USB serial port on the host... The rest of the host code would be
pretty trivial.

Too bad that I am not an electrical engineer....    :)