Dobbertin Industrie-Elektronik implemented their own CPM+. The sign on message displays "CP/M Plus Amstrad Consumer Electronics plc".
Their CPM+ has:
- detects on boot if there is at least 128KB memory and error if there isn't.
- a RAM-Disk
This uses a Dk'tronics/Dobbertin RAM expansion. It doesn't support Vortex RAM expansion. The size of the RAM expansion is auto-detected allowing ram disk sizes of 62KB, 190KB, 254KB, or 444KB. These correspond to 256KB RAM, 256KB Silicon Disk and combined RAM and Silicon Disk (512KB RAM) expansions or to partially / fully populated Dobbertin expansions. The Ramdisk is accessible in CPM+ with drive C:. In early versions is was M:.
- Support for the Dobbertin HD20 Hard disk
This requires a HD20 capable X-DDOS because it checks for a specific variable set by X-DDOS if it detects the hard-disk. The main hard disc functions are in bank 0, with common hard disk buffer read/write in the common C7 bank at &FE00. The hard disc is accessible in CPM+ with drive D,E,F and G.
DPB description:
SPT: &00cc (204) (128 byte records) BSH: 5 BLM: &1f EXM: &1 DSM: &50D DRM: &1ff (512 entries in directory) AL0/AL1: &00f0 (4 blocks for directory) CKS: &8000 (fixed disc) OFFS: &0001 PSH: &02 PHM: &03
- supports both 50hz and 60hz displays.
If 60hz is detected the Vertical Sync is set to 16 lines and the hsync is set to 4. Otherwise it remains unchanged.