Taken from from DABS PRESS advert A&B Computing Jan 1988 p.18

MOS Plus by top BBC programmer David Spencer
This low-cost ROM tidies up all those loose ends in the Master 128 MOS, including fixes for the *CLOSE and *EDIT bugs, ADFS, Format, Backup, and Verify in ROM. Alarm Clock system (uses Clock chip facility), Single drive backup using SRAM and much more. £12.95 ROM (£7.95 disc)