The GVP HD+ is one of a long line of SCSI controllers and RAM expansion produced by Great Valley Products (GVP) for the Amiga line of computers. The HD+ is a later Impact Series II controller which housed the controller inside of a sidecar connected to the external expansion connector of the Amiga 500. Inside, there was an internal SCSI connector as well as 4 30-pin SIMM sockets and mounting space for a half height 3-1/2" hard disk. Unlike earlier GVP products, the RAM expansion on the HD+ was done using industry standard SIMMs, vice the proprietary GVP SIMMs. It had an external connector for a standard DB-25 SCSI connector as well as it used it's own power supply. There is also a switch on the rear of the unit to turn it on and off, and a switch on the front of it to determine whether the A500 will boot from the SCSI controller or from it's floppy drive since a number of games required it to boot from floppy.

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