2 Feb
2013
2 Feb
'13
10:11 a.m.
On 02/01/2013 09:42 PM, Jeff Jonas wrote:
Long ago when SCSI was young
and just an 8 bit parallel bus,
Ampro littleboards advocated using the SCSI bus
for peer to peer communications, not just master/slave.
Did anyone else do that?
One used to be able to do it with Suns, in the Good Ol' Days. I've
not done it myself but have seen it done. It was really quite neat.
A fellow contacted me with this problem:
I have a couple of Kurzweil synthesizers (/samplers/sequencers):
K2000RS and K2600X . They have integrated floppy and SCSI HDDs
for storing configuration, composition and audio sample data.
They're actually 68000 CPUs with a Kurzweil OS,
managing IO among peripherals
(keys, SCSI, display LCD, MIDI, etc) and several proprietary DSPs.
But there's no serial/network/etc IO.
I'm interested in trying to use their SCSI
to interface them with a (Linux) PC somehow.
Any ideas? Like maybe some webpages
describing projects that have networked older
(preferably 68xxx) CPUs over their shared SCSI bus.
My understanding is that a Kurzweil and a Mac were sometimes configured
each as a SCSI device on the same SCSI bus as the HDD,
and either host could alternate accessing the HDD
once the other host was no longer issuing
potentially conflicting SCSI commands to the HDD.
I don't see how just read commands could conflict,
but perhaps the HDD wasn't able to multiplex commands
targeting different hosts in any overlap.
But evidently people were transferring samples
between Kurzweil and Mac this way.
Read commands could conflict in the simple case of a host assuming it
has exclusive control of the bus. I don't believe any reasonable SCSI
host adapter chips would behave that way, but some early SCSI host
adapters were implemented using discrete logic or with a simple
interface that needs lots of OS handholding (like the NCR 5380) and
high-level interactions are done in the driver.
Unless you want to dig deeply into the Kurzweil firmware, I don't
really see this working out, though. This is assuming you don't have
any documentation on how the Mac interacts with the synthesizer or the
on-disk formats in use.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA