BBC Master 128

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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.

The Master 128 was designed so that internal co-processors could be fitted , as well as the external, Tube connected, second processors. There were 2 internal co-processors:

Manuals & documentation

For documents for all Master computers see Master Computers.


I have two exampleas of a Master 128, the first is in original condition, the second has been updated with recent (2009) upgrades:

Master 128

I never bought a Master 128, instead I kept expanding my BBC Micro. So I bought this Master 128 on November 2002 on ebay.
Here are some photographs:

Master 128 & Cub monitor  

Master 128 & Microvitec Cub monitor

Master 128 and Cub Monitor. A number of 3rd parties produced plinths to support the monitor above the computer with 5.25" disc drives included.

Master 128 top  

Master 128 (top)

Master 128 from above showing the 2 cartridge slots on the right.

Master 128 rear

Master 128 (rear)

The back of the Master 128 showing the ports from the left: Econet, Audio Out, Cassette, RS423, Analogue, RGB, Comp Video and UHF. Although the Econet socket is fitted, the Econet module must be fitted internally before it can be used.

Master 128 bottom  

Master 128 (bottom)

The bottom of the Master 128 showing the ports from the left: Tube, 1MHz Bus, User Port, Printer and Disc Drive. The power supply disc connector is on the right. The serial number is above the Tube socket.

Master 128 open  

Master 128 Open

Master 128 open, showing the power supply on the left, the expansion gap (I have a Watford Electronic Modem that fits here), at the bottom of the gap you can see the batteries for the CMOS RAM, in the top right the Econet daughterboard and in the middle right the cartridge sockets. On the keyboard next the the Break key is the white plastic Break key lock.

Master 128 motherboard  

Master 128 motherboard

Master 128 motherboard, the sideways ROM sockets are on the right hand side. The ROM with the white label is the ANFS network filing system ROM. On the left hand edge in the middle is the expansion connection, just above the brown keyboard connectors.

Upgraded Master 128

This Master 128 was upgraded in 2009 with:

I originally planned on using a Windfall Engineering GoMMC for storage but ran out of ROM Sockets, so I have used a RetroClinic Compact Flash Drive.

Upgraded Master 128

 Upgraded Master 128

Upgraded Master 128 showing the additonal ROMs:

Upgraded Master 128 right

Upgraded Master 128 (right) 

Upgraded Master 128 right hand side showing the switch to swap between MOS 3.20 and MOS 3.50.

Upgraded Master 128 open

 U[grade Master 128 with top cover removed

Upgraded Master 128 circuit board

 Upgraded Master 128 circuit board

Upgraded Master 128 circuit board showing:

Here is a HiRes picture of the upgraded Master 128 circuit board .


Serial No.01-AMB15-018392601-AMB15-0226490
Mortherboard0243,000 Issue 20243,000 Issue 2
CPUCMD 65SC512P-2GTE 65SC12P-2
CPU Clock2MHz2MHz
Disc ControllerVL1772-02PVL1772-02P
Disc Filing SystemADFS 1.50
DFS 2.24
ADFS 2.05
LANManager 0.25
DOSFS 1.12
OSOS 3.20OS 3.20/3.50
0259,200 Issue 2
Add-in/Upgradesn/aSprow ARMCoPro
Sprow 10/100 Net Ethernet
RetroClinic DualOS
RetroClinic External Compact
Fash drive
Sprow Doomsday ROM