HP 9885M - Flexible Disk Drive The HP 9885M is a modular 8" floppy disc drive developed originally for HP 9825A desktop computer. It has been used with other desktop calculators serie 9800 (HP 9831A, HP 9835A, HP 9845A/B) and with HP 21MX system. The version "M" (Master) included a built-in controller, while version "S" (Slave) was without controller. Up to eight HP 9885M can be connected in one system and up to three slave drives could be connected to one master unit. The Slave drive cannot be connected directly to the computer. Each unit, master and slave may contain a disk for storage of date and each can be addressed individually. Access to a HP 9885 drive is made through a ROM in the computer. The HP 9885M accepted SS/DD 8" floppy discs with maximum storage capacity of 514 kbytes. The disc has 67 tracs with 30 records per track. The rotation speed was 360 rpm with 267 msec average access time. An introductory price in 1976 was about USD 4000.