A freaky computing contraption cooked up by Ross Technologies. Essentially it was a stripped-down SPARC base squashed into a 5-1/4" full height disk drive form factor. Often sold in kits to retrofit into an existing PC, these machines were intended to turn any PC into a simultaneous NT/UNIX workstation. Unfortunately for Ross, the basic model cost ~$9k and the things were mighty noisy, and so discouraged many purchasers. Apparently there were rack-mount chassis for these things that would allow you to to jam six or so of these beasties in a 4U rack space. The SparcPlug was Fucked Up Noisy.