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Above all the BBC computer is an expandable system. The Model A can be expanded to the Model B at any time. A floppy disc interface and one or more floppy disc drives can be added later. A floppy disc unit will enable you to load and save programs in a matter of a second or two. If you would like to keep a mailing list, or any large data-base (like lists of products and suppliers) then you will find floppy discs invaluable since they work so much faster than cassette tapes.
For many applications you will want to add a printer. There are many types and the Model B can work with all except very old, slow printers such as the 10 characters per second Teletypes®.
Choosing a printer can be a difficult decision. A booklet from the Council for Educational Technology, 3 Devonshire Street, London, W1N 2BA called "USPEC 32B" provides much impartial guidance. A Daisy Wheel printer will produce high quality print at a relatively high price. On the other hand, a dot-matrix or ink-jet printer is a great deal cheaper and quite adequate for many jobs. The BBC computer can connect to RS232 serial printers or Centronics® type parallel printers.
The high quality colour monitor will enable you to see the finest detail produced by the computer's high resolution colour circuits.
The Teletext add-on unit enables the BBC computer to look at the BBC and ITV CEEFAX, and ORACLE pages in the normal way. In addition, with this unit you can receive and store, on cassette or disc, computer programs that are transmitted over the air free of charge (so called Telesoftware).
The Prestel add-on unit connects the BBC computer to a British Telecom telephone line. Once connected, you can use all the facilities of Prestel and, again, load computer programs supplied via Prestel. The transmission of computer programs in this way is known as Telesoftware. The Prestel unit contains an approved modem with which you can communicate with large computer systems world wide as well as with anyone else who has a BBC computer and Prestel unit. In this way you can send programs, or sales results or whatever, to anyone else in the world, at very low cost.
The 8 bit user input/output port on the Model B can connected to a wide range of external devices. These include: bit-pads which enable you to trace or sketch pictures on to the screen. These can be used when entering engineering drawings into the system. Robot arms for computer controlled movement, video disc units enable one of a million pictures to be rapidly retrieved, and fast analogue interfaces enable the computer to record fleeting events.
There is space inside the computer to add the voice synthesis unit. This gives the computer a vocabulary of over 100 words and further words can be built up or loaded in from cassettes or disc or ROM-pack. It is very easy to use this unit.
The ROM-pack interface can be added to enable the computer to use programs held in convenient cartridges. This makes it very easy to play games and to get a particular applications-program working.
The Econet option will allow you to connect over a hundred BBC computers together. A normal Econet system consists of several Model A or Model B systems with Econet interfaces connected to a printer via a printer-server computer and to a floppy disc via a file-server computer. The only additional costs are for cable, plugs and sockets and for the file-server software. This is an extremely cost-effective way of providing printer and floppy disc facilities for a group of users. Each user on the Econet can communicate with other users (unless barred by a supervisor), and there are many other facilities. For example, one user can request a copy of another user's screen.
The computer can be interfaced to larger and faster networks such as the Cambridge Ring, thus opening up possibilities for ultra fast local networks and true distributed processing.
The 1MHz bus connector is provided to enable users and other manufacturers to connect additional specialist hardware to the BBC computer. For example, a range of Eurocards and a racking system are available. The Eurocards include laboratory interfaces, additional parallel and serial interfaces, EPROM programmers and fast analogue to digital converters. The Prestel and Teletext units also connect to this "bus".
The Tube® is a connector and software interface which permits very high speed communication between the BBC computer and a second processor. The "second processor" is another computer system in its own right, but one that uses the BBC computer for all the time-consuming input/output operations.
The first "second processor" is a fast 6502 with 64K RAM. This should be able to run any program that a Model A/B can run but with increased speed and with more space available to the user. Of course only programs that adhere to the Tube®'s software discipline will run correctly.
Another second processor option is a Z80 with 64K of RAM. The software with this unit allows CP/M® programs to be run with more memory than a normal CP/M environment. In addition, the main user program is left free to do calculations, leaving the BBC computer to deal with graphics, printers, clock, floppy disc, etc.
A future second processor will be a 16 bit machine with 32 bit internal architecture. This processor, the National semiconductors 16032, can be used with up to 16 Megabytes of RAM.
As you will be aware, there is very considerable room for expansion in the future - an essential feature in view of the rapid changes in technology.