Some notes on making a custom cable for daisy-chaining multiple E-MU samplers to share an external SCSI disc.
The single SCSI centronics socket on the E-MU Ultra series samplers is
fine for a single device but not so good for multiple units. I wanted to
permanently connect a set (flock?) of 5 E-MUs to a disc box, as the
existing method using a single centronics-to-scsi2 cable meant a lot of
plugging & unplugging and scrabbling around the back of the units.
Not surprisingly an off-the-shelf cable was unavailable, so a home-brew
one was attempted using a 50-way ribbon cable with IDC (crimp-on) plugs.
The SCSI-2 plug is a lot smaller so the 50-way cable is split 25 each
So much for IDCs reducing assembly time! It's not just a case of
splitting the ribbon in the middle; you have to connect alternate wires
to each side. This meant separating the wires from each other, making
them difficult to hold in place for crimping...
...so I wouldn't recommend this type of connector if you can avoid it - they are also extortionately expensive compared to the centronics. Don't be tempted to use a 25-pin connector unless it's a very short cable - the extra 25 wires act as screens between each signal wire.
Due to the side-by-side layout above a keyboard, with another off to the side over another keyboard...
...the cable ended up being 3m long, so there was a lot of doubt,
especially as it's unscreened...
...but the good news is it all works a treat!
The next photo shows what each E-MU sees - the two external discs D0 and D1, with D8 being its own internal IDE disc. The manual warns about multiple hosts so you can only access the external discs from one E-MU at any one time (they may crash otherwise and you'll have to power off & on), but you can move data around by using the externals as an intermediary.
A PC link via SCSI is not part of my setup (I use an IcyDock removable IDE drive), but in theory you could replace the terminating plug on the disc box with a SCSI line from a PC, bearing in mind this will lengthen the cable.
A room re-arrangement meant all E-MUs were stacked in one rack, but the
SCSI cable still connected ok... phew!
The 4th one down has the IcyDock removable IDE drive in FAT format which allows transfers to/from a PC.
Below are close-ups of the SCSI settings for
4 of these; to see the screen details, click the photos and zoom in.
The external SCSI discs are located below the stack, and have SCSI id nos. 0 & 1. One of them has a SCSI terminator attached; this is one end of the chain.
The left photo shows the Master, Setup, SCSI
screens. The E-MU SCSI ids are set to 4, 5, 6 & 7 respectively, with
the terminator set to 'on' on the first E-MU only; this is the other end
of the chain.
The right photo shows the Disk screens. Each
E-MU can 'see' both SCSI discs (Quantum & IBM) and their own
internal IDE disc, so banks can be saved/loaded between them, or whole
folders of banks transferred in one operation using the Disk, Utils,
Click & zoom for details.