The DEC pdp-11 16-bit microcomputer was one of the most successful general-purpose computers ever manufactured, second only to the VAX. This example, a 1984 vintage pdp-11/23 in deskside pedestal, uses the famous LSI-11 single-board Q-BUS procesor, with 512Kword RAM and a 150 MB hard disk. The dual RX50 5.25" floppy drive is prominently placed in the front panel of the unit, right below the console. The console has lights for floppy 1 & 2 write protect, and lighted swtiches for the same functions on the fixed media. This model also has lighted run/halt switches. The 11/23 is a multi-user system and the software often added task-swapping functions by means of hotkeys on each terminal's keyboard. The most popular software for the pdp11 is RT-11 and RSX-11. Even today, many pdp-11's are still in use in commercial applications such as embedded control systems for industrial equipment, because they are reliable and easy to use. The pdp-11 is an excellent hobby machine, if one can locate software. Currently, Mentec (The U.K.) maintains the O/S software.