BBC Master Turbo

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 The Master Turbo is a Master 128 with a Master Turbo Module  installed. I am not sure if the Turbo Modules were factory installed and sold as Master Turbos, or dealer/customer installed. However the price lists for 1986 only list the Master 128 and the Turbo Module (£125). The Master Turbo Module had a faster CPU (4MHz instead of 2MHz) and almost 64KB of usable memory which gave approximately 50% performance improvement over the Master 128. It ran the host operating system in the same way the earlier BBC Mirco 6502 second processors did. I bought my Master Turbo from a friend who needed a PC to go to college in 1997.

I had some fun preparing the Master Turbo for the web site. Firstly it wouldn't boot correctly, just beeped and left the cursor in the top left. Following the Master Service Manual, I removed the co-processor, but no change. Then I got a spare Master which I had bought to provide a spare psu for an A500 which had blown its own psu (did you know they used the same psu?). I swapped the keyboard, but no boot. So rather than replacing IC16 (CF30047), I swapped the motherboards. This worked and the Master booted. I reinstalled the Turbo module and everything still worked. The only differences are that the replacement motherboard is an issue 1 board, whereas the original motherboard was issue 2 and the Master has gained an Econet Module.

But just as I came to take the first picture, there was a sizzling sound, a cloud of evil smelling smoke and the psu failed. So the psu that was going to the A500 has now gone to the Master Turbo.

Manuals and documents

 Here is the Acorn 65C102 Co-Processor User Guide 

For documentation for all Master computers see Master Computers .

Master Turbo

 Here are some photographs:

Master Turbo & Cub monitor  

Master Turbo

Master Turbo and Microvitec Cub monitor on a plinth with 5.25" and 3.5" disc drives. On the screen is the Turbo (65C102) Co-processor startup message and a list of the ROMs fitted.

Master Turbo open  

Master Turbo open

Master Turbo with the top off, showing the Turbo co-processor in the middle of the picture. Also note the Econet module in the back right and the ANFS ROM with a white label above the cartridge slots.

Acorn ADC06 65C102 Co-processor top

Acorn Master Turbo co-processor card (top)

The Turbo co-processor card, the Ferranti ULA on the right is the TUBE interface to connect to the Master 128. Next to it is the 65C102 CPU with the serial number on top. The card also has 64K RAM and fits theinternal TUBE connections in the Master 128.


Serial No.01-AMB15-0143103
Motherboard0243,000 issue 1
CPU clock2MHz
Disc controllerWD1770-PH
Disc Filing SystemADFS 1.50
DFS 2.24
OSOS 3.20
Econet0243,020 Issue 2
Co-processor board0243,030 Issue 2
Co-processor serial no.01-ADC06-0101403
Co-processor CPU65C102
Co-processor CPU clock4MHz
Co-processor Memory64KB
Co-processor OSOS 3.20