to general users, which sold only a few hundred units. It recorded images in greyscale, and the quality in newspaper print was equal to film cameras. In appearance it closely resembled a modern digital single-lens reflex camera. Images were stored on video floppy disks. Silicon Film, a proposed digital sensor cartridge for film cameras that would allow 35 mm cameras to take digital photographs without modification was announced in late 1998. Silicon Film was to work as a roll of 35 mm film, with a 1.3 megapixel sensor behind the lens and a battery and storage unit fitting in the film holder in the camera. The product, which was never released, became increasingly obsolete due to improvements in digital camera technology and affordability. Silicon Films' parent company filed for bankruptcy in 2001. Early true digital cameras By the late 1970s, the technology required to produce truly commercial digital cameras existed. The first true portable digital camera that recorded images as a computerized file was likely the Fuji DS-1P of 1988, which recorded to a 2 MB SRAM (static RAM) memory card that used a battery to keep the data in memory. This camera was never marketed to the public. The first digital camera of any kind ever sold commercially was possibly the MegaVision Tessera in 1987 though there is not extensive documentation of its sale known. The first portable digital camera that was actually marketed commercially was sold in December 1989 in Japan, the DS-X by Fuji The first commercially available portable digital camera in the United States was the Dycam Model 1, first shipped in November 1990. It was originally a commercial failure because it was black-and-white, low in resolution, and cost nearly $1,000 (). It later saw modest success when it was re-sold as the Logitech Fotoman in 1992. It used a CCD image sensor, stored pictures digitally, and connected directly to a computer for download. Digital SLRs (DSLRs) Nikon was interested in digital photography since the mid-1980s. In JULY of 1986, while presenting to Photokina, Nikon introduced an operational prototype of the first SLR-type digital camera (Still Video Camera), manufactured by Panasonic. The Nikon SVC was built around a sensor 2/3 " charge-coupled device of 300,000 pixels. Storage media, a magnetic floppy inside the camera allows recording 25 or 50 B&W images, depending on the definition. In 1988, Nikon released the first commercial DSLR camera, the QV-1000C.