Data Media Disc System

Professional storage media

An early disc solution for the CPC 464 from german company Data Media. Available in three versions with two, three, or four 5.25" drives. The capacity per disc is 780Kbytes, the four drive version was announced to store up to 3.2Mb of data. Due to the price and AMSDOS-incompatibility this system lost to another german third-party company of disc systems for the CPC, Vortex Computersysteme.

FDOS

The disc operating system was called FDOS (non-AMSDOS compatible) and was stored on the controller board in an 8Kb eprom. Unlike as under AMSDOS, the cassette commands are hooked (ie. LOAD does access the normal cassette routines). Instead, the disc is accessed via RSX commands (according to the review: |LOAD "filename" - though that info appears to be incorrect - correct should be |LOAD,a$ with comma, and for 464 BASIC: with string variable). The supported RSX commands are:

|MON         Monitor/Debugger
|CPM         Start CP/M (or other boot-able disc)
|A,|B,|C,|D  Select drive A-D
|LOAD        Load File
|SAVE        Save File
|DIR         Show Directory
|ERA         Erase File
|REN         Rename File
|OPENIN      Open Input File
|OPENOUT     Open Output File
|CLOSE       Close Input/Output File
|READ        Read from Input File
|WRITE       Write to Input File
|RUN         Load and Start File
|MERGE       Merge File
|INIT        Format Disc

Filesystem

FDOS uses a special filesystem with 20 characters per filename, and max 72 files per disc (much different to standard CPC and CP/M filesystems which use 8.3 characters per filename).

CP/M

According to the review, the data media disc system was shipped with CP/M, and included support for confuguring the drive parameters of each drive to work with other CP/M filesystem dialects from other systems.

Whilst being more or less incompatible with 3" CPC disc format, this did at least provide compatibility with 5.25" CP/M discs from other systems.

Controller

The drive unit contains a WD2797 controller chip from Western Digital. That, unlike as all other CPC disc interfaces, which typically contain uPD765 controller chips.

RS232 Interface

As a special feature the controller board had an integrated RS232 interface. This was mentioned as optional feature in the review from 8/1985, it wasn't mentioned at all in the advert from 8/1985, it was mentioned as built-in feature in the advert from 12/1985 (so, it's unclear if all units were delivered with installed RS232 interface).