ROLAND MKS-50 w/ PG-300 PROGRAMMER SN 663289

via this auction

"The MKS-50 is the rack mount module version of the Roland Alpha Juno 1 and 2. The PG-300 controls the MKS-50 and can also be used with the Alpha Juno 1 and 2. It offers complete control over all editable parameters in an easy to use, well designed controller."