Micropolis MDOS ("Micropolis DOS", or "Micropolis Disk Operating System") is a disk-based and booted operating system for Intel 8080 and compatible processors developed by Micropolis Corporation for use with early (S-100 bus based) Micropolis disk controllers. It offers similar functionality as many other disk operating systems at the time, like Northstar DOS or CP/M, but has its own command structure and syntax and is not compatible with CP/M, although CP/M later became a de-facto standard. This archive manual on pages 72 ff. (section 4) has details on how to work with MDOS. MDOS being a software package, provided a number of components, the main "executive" program, with an interactive interface, file and disk copy tools and "Micropolis PDS" (Program Development Systen) which includes assembly language development tools and Micropolis' BASIC interpreter, "Micropolis Disk Extended Basic", aka "MBASIC".

A variant of MDOS named "OSM" (Operating System for MicroDisk) was shipped with Micropolis' first hard-disk storage subsystem, the 8" rigid disk based MicroDisk™ enclosure. Similar in structure to the floppy disk based OS variant, it included PDS, BASIC, file handling and system control tools while being multitasking and multiuser capable.

During the late 1970s, Micropolis had a close relationship with early computer manufacturer Vector Graphic, Inc. In 1978, Vector introduced a Zilog Z80 based system, the "MZ". In their co-operation Micropolis supplied floppy disk drives and controller hardware OEM for the new "Vector MZ" computer. In order to enable Vector customers who had used older Vector machines with Northstar controllers and (Shugart) drives to migrate their data to the MDOS based "MZ" computer generation, Vector Graphic Inc. offered yet another disk operating system variant that could sit in-between. With Vector's "MZOS" operating system, MZ computers equipped with both, a Northstar controller disk setup and a Micropolis disk and controller combo, were able to copy data from a Northstar DOS disk to a MZOS formatted disk as MZOS is binary compatible with Northstar software. This was beneficial as Micropolis drives and disks offered more capacity and users could not only migrate existing data but also merge multiple disks into one. Although MZOS is sometimes refered to as Micropolis MZOS, the operating system was not developed by Micropolis but by Vector Graphic employee Neale Brassell in 1978 for Vector Graphic Inc.

Aside from Vector Graphic, other manufacturers adopted MDOS for their machines as well, as it suggests itself when a system uses Micropolis drives and controllers for non-volatile storage. One example is the Burotic Smaky 6, an early Suisse computer that used a customized version of Micropolis MDOS named SAMOS.