+3DOS: Difference between revisions

+3DOS is the disk operating system of the [[ZX Spectrum +3/2A/2B|Sinclair ZX Spectrum +3 and Black +2 models]]. It is a [[CP/M]] compatible filesystem and is integrated into the +3 BASIC.

The DOS routines are located in ROM2 (the +3DOS ROM) and the code for the Sinclair BASIC integration is located in ROM1 (the Syntax ROM). The +3DOS extensions to the BASIC are only present when running the +3 BASIC ROM (128k mode). There is no provision for using +3DOS from ROM3 (the 48k mode rom). In fact when 48k mode is selected from the main menu the ROM paging is locked and it is impossible to access the +3DOS ROM again until the spectrum has been rebooted.

Despite the lack of disk interface hardware the Black +2 models contain the same Operating System ROMs as the +3. Therefore the +3DOS routines are all present. The ROMs detect the absence of the disk interface hardware and set the title of the boot menu to "128k +2A" as opposed to "128k +3". The RAMDisk (Drive M:) is available on the Black +2 machines but obviously the floppy drives (A: and B:) are not present. Attempting to access drive A: or B: will generate a "Drive not found" error. The default drive for load/save operations on the +2A/B is the tape (drive T:) however the CAT command (list drive catalogue) defaults to the RAMDisk (M:)