Computers Overview
Commodore PET
Sinclair ZX80
Sinclair ZX81
BBC Micro
    About
    Articles
    Manuals
    Options
    Photos
    Software
    Tips for the newbie
    Z80 2nd Processor
Commodore 64
Sinclair ZXSpectrum
Memotech MTX
Memotech CP/M
Tatung Einstein
Atari ST
Commodore Amiga
PDAs
DEC 3000 AXP
OpenVMS
Raspberry Pi

 

 
 
 

The BBC Microcomputer System (BBC Micro)

BBC Micro - Z80 Second Processor Upgrade

The Tube Interface

The Tube is an expansion interface built into the BBC Micro which was designed to enable the computer to communicate with a second processor. The BBC Micro host processor would then handle the Inputs and Outputs (I/O) while the second processor took over program execution. Available Second Processors included a higher speed MOS 6502 running at 3MHz, a Z80 running at 6MHz, a NS32016 running at 6MHz as well as an ARM Evaluation System using an ARM1 processor running at 8MHz.

The Second Processors, and other options like the Teletext Adapter and Prestel Adapter, were all built into wedge shaped enclosures, often called "cheese wedges", which sat side-by-side with the BBC Micro as shown in the photo of the Teletext adapter above, connected via a ribbon cable to the Micro's Tube interface port. The photo on the right is a Z80 Second Processor, the picture was downloaded from Chris's Acorns.

Z80 Second Processor

The Z80 Second Processor was supplied with a copy of CP/M 2.2 and a number of bundled programs :-

MemoPlan A Word Processor
FilePlan A Personal Database
GraphPlan A Spreadsheet Modelling Program with graphics
Accountant An Integrated Accounting System
Nucleus A Software Development System
BASIC A Z80 Version of BBC BASIC
BASIC Pro Professional BASIC allowing access to CP/M programs
CIS COBOL Implementation of the COBOL Language

To use the Z80 Processor upgrade, the BBC Micro required a disk interface and a pair of 80 Track disk drives. Although the Beeb continued to drive the TV output, the display of 80 column text really required the use of a colour or monochrome monitor.

 

 

 

mailto: Webmaster

 Terms & Conditions