Year 506 (DVI) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Messala and Dagalaiphus (or, less frequently, year 1259 Ab urbe condita).

<storage> The first full-height 5.25 inch hard disk drive for personal computers, introduced in 1980 by Shugart Technology (now Seagate Technology). The ST-506 stored up to 5 megabtyes after formatting using MFM encoding. It transferred data at 625 kilobytes per second. The ST-506 (like the ST-412) was interfaced to a computer via a disk controller. The interface was a faster version of the Shugart Associates SA1000 interface, which was in turn based upon the floppy disk drive interface. Two cables connected the controller to the disk. The 34-pin control cable controlled mechanical motion and data was read or written serially using two pins of the 20-pin data cable. Other companies copied the interface, creating a universal {de facto standard} that was further strengthened by its revision to support Seagate's 10 MB ST-412 drive that was adopted for the IBM PC XT. Around 1990, SCSI and ATA superseded ST-506. These eliminated the problems of matching controllers to drives by physically integrating a controller with the drive, allowing interleave ratios and other disk parameters to be optimised by the manufacturer rather than the system integrator. Connector pin-out (http://www.gamesx.com/hwb/co_ST506.html). (2007-03-06)

Area code 506 is the telephone area code in the North American Numbering Plan (NANP) for the Canadian province of New Brunswick. The area code was created in 1955 in a split of numbering plan area (NPA) 902.