The Minolta RD-175 was probably the first digital SLR which was hand portable. Up until 1995 when this was introduced, the only digital SLR on the market had a very bulky external digital storage system. There were other primitive digital cameras but they were much lower resolution. Minolta combined an existing SLR with a three way splitter and three separate CCD image sensors, giving 1.75M pixel resolution.  The base of the DSLR was the Minolta Maxxum 500si Super (the Dynax 500si Super in Europe and as Alpha 303si Super in Asia). Agfa produced a version of the RD-175 retailed as the Agfa ActionCam.
Since state of the art CCD resolution at the time was not sufficient for Minolta, the light entering the central 12 × 16mm area of the RD-175's focal plane was compressed by 0.4x relay optics behind the focal plane, similar to the optical reduction system used in the Nikon E series. The light bundled on the smaller sensor area increased the effective sensitivity (ISO) by 2 2⁄3stops. Then the light was split and sent to three separate 4.8 × 6.4mm sized 768 × 494 pixel (3 x 0.38 megapixel) image sensors, two used for green and one for the red and blue color, reducing the sensitivity increase to about 2 stops. The only usable ISO was 800.
The three images were combined digitally and interpolated to the final size of 1.75 mega-pixels (1528 × 1146 pixels). Images were stored on an internal PCMCIAhard drive. The camera used Minolta AF A-mount lenses with a crop factor of 2.