Acorn BBC Master 128

The Master 128 is the base model of the Master series. It was priced at £499 (inc. VAT). Unlike the BBC Micro, the Master 128 did not change during its lifetime, there was a single issue motherboard and a single OS (MOS 3.20) although an updated MOS 3.50 was released as an upgrade. MOS 3.50 was only available as an upgrade because it broke some BBC software.