Alloy Computer Products Inc, Framingham, Massachusetts, has come up with a low-cost extender designed to enable two or three users to share files and databases stored on the office PC. The product comes in two parts: pc-Twin is an 8088 processor board that comes with an IBM 3101 ASCII terminal and a 25 foot cable, and includes a Babynet plug-in board for the MS-DOS micro. The package costs $1,700, supports MDA, CGA, EGA or VGA host video. The company sees the product being used where a doctor and an office manager or a lawyer and secretary need to share files; ships August.