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1 : Getting Started        


The 512 Discs

The discs supplied with the Master 512 contain the DOS Plus Operating System, which provides the 512 with its PC-compatibility, and GEM (Graphics Environment Manager), the graphical 'WIMP' interface by Digital Research. The version of GEM provided with the 512 is specially written for it and works considerably faster than many versions on other PCs. The version supplied with the current release of DOS Plus is even further optimised over earlier issues.

For current purposes we need only note that the four issue discs contain:

DISC 1     DOS Plus boot and System Utilities
DISC 2     GEM applications
DISC 3     GEM data
DISC 4     Miscellaneous Utilities

DISC 1 contains the Operating System and a number of DOS Plus Commands. If you are familiar with the BBC or Master, you will appreciate that the disc filing system (DFS or ADFS) and the Machine Operating System (MOS or OS) are both built into the computer, contained in a read-only memory chip (ROM or EPROM). In consequence the only action required to start the system is to switch on the power, since everything is ready and waiting for use.

In contrast many computers, like PCs, have only a small section of permanent program in ROM or EPROM. This is just enough to load the main Operating System and filing systems from disc. This small program is correctly known as a bootstrap loader, but this is commonly shortened to boot. Hence the expression 'booting a system', and so called boot files on the BBC, although these are slightly inaccurately named, as you'll see. Frequently the DOS Plus systems disc is also referred to as the boot disc, although the bootstrap loader is not even on the disc.

When you start the system with CTRL-BREAK (see below) the bootstrap loader is executed automatically. This action must be carried out by hardware, as the machine 'knows' nothing at this stage. The bootstrap loader is a small program that is only capable of accessing the disc controller in a very restricted way, but enough to load a file containing the full Operating System. After this is loaded, control is passed to it and the system is live and fully functional.

There are many advantages to having the Operating System on disc. Any version of the Operating System can be used by loading from the appropriate disc, and substantial improvements can be made without having to change any hardware. Furthermore, many different types and sizes of floppy and hard disc control software may be used. Of course there are also disadvantages. The disc must have a copy of the Operating System if it is to be used to boot the computer – this uses up some of your disc space. In addition, the Operating System must permanently occupy some of the computer's main memory. In the case of DOS Plus in the 512 this accounts for considerably more than 100k bytes of the original 512k. Another disadvantage is the possible inconsistencies which may arise if several boot discs are used, each perhaps containing an auto-running application, but containing different versions of the Operating System.

Starting the System

Before attempting to connect and run the 512 you must ensure that your BBC hardware is suitable. For Master series machines this can be taken as read, but model B or B Plus users must ensure that they have a WD1770 disc controller (8271 will not work under any circumstances) and are using an Acorn or compatible Advanced Disc Filing System (ADFS). The 'standard' or original non-hierarchical DFS is not suitable, even if it uses the 1770 controller.

You must also have a minimum of a double-sided 80-track disc drive. In practice, life will be very uncomfortable unless you have two such drives, or one and a Winchester 'hard' disc (any size of Winchester will do, 20Mb or more is recommended).

If the above conditions are met, the first operation is to ensure that the 512 hardware is properly connected. In the BBC Master the 512 board can be fitted in two ways. It can be connected internally by direct fitting to the circuit board using the pins and sockets provided, or it can be connected externally, via the external Tube, (socket located in the recess underneath the micro) using an Acorn Universal Second Processor Unit. In Model B or B Plus micros the connection is always via the external Tube as no internal connections are provided as standard, nor can they be fitted as options.

At least two other manufacturers can supply an external Tube adaptor for the 512, and if these are used you should refer to their instructions for fitting and use.

Note that some magazines and advertisements have given the impression that the standard Acorn Universal adaptor is not an option for the 512 with Model B or B Plus micros. This is not the case. Not only is the Acorn adaptor eminently suitable, while reducing the likelihood of problems with guarantees in the event of hardware failure, it can, at the same time, be a less expensive option too. Bear this in mind if you are about to purchase.

The next step to using the 512 is to load the Operating System. The method used will depend on the type of hardware fitting used. Both methods are described below, first with the internal tube connection in a Master, followed by the external tube fitting for any machine.

Throughout this book the A> prompt is assumed as being the start point for all operations carried out after DOS Plus has loaded. In practice you may well be operating from drive B, drive M if you are running a memory disc (see Chapter Nine), or drive C if you have a hard disc (ie a large capacity Winchester drive).

Internal Tube Start-up

If you have a Master 128, with Master 512 co-processor fitted internally:

1. Enable the Tube using:

*CONFIGURE INTERNAL  (if required – see next page)

2. Insert DISC 1 into BBC drive 0.

3. Press CTRL-BREAK. This means press and release BREAK whilst holding down the CTRL key. The disc will be accessed and after a few moments the Digital Research logo will appear and the system will then be loaded. On completion the DOS Plus prompt will appear thus:


External Tube Start-up

If running on a Master 128 type:


This may not be required if your Tube is already set to 'External'. To check type *STATUS TUBE. An external setting will remain until you alter it.

1. Turn on the Second Processor unit mains power switch.

2. Insert DISC 1 into BBC drive 0.

Press CTRL-BREAK. After a few moments the Digital Research logo will appear and the system will load. You will then be prompted for the time and date, unless you have an AUTOEXEC.BAT file (see Chapter 11) on your startup disc. This should be entered in the form DD/MM/YY followed by RETURN.

For example if the date were July 24th 1989 the entry would be:


Next you will be prompted for the time, based on the twenty four hour clock, in the format of HH:MM:SS followed by RETURN.

The seconds are optional (and pointless for manual entry) and will default to zero if omitted. For example, if it were 4.22pm your entry would be:


If you do not wish to supply either of these items, pressing RETURN (only) will allow the load to proceed. Be aware, however, that DOS Plus date and time stamps files whenever they are updated. Failing to supply an accurate date or time will render this valuable information useless. If you have a Master or BBC with Master-compatible Real Time Clock (eg the PMS Genie Watch) then just pressing RETURN or omitting clock setting by using an AUTOEXEC.BAT file causes no problems. However, if you are working without a Real Time Clock, beware that the default time and date used by the system is midnight on 1st January 1980 (at startup – the clock is then internally incremented). In this case, it is worthwhile including TIME and DATE commands in any AUTOEXEC.BAT file.

If you have not already done so, you should copy the contents of a newly formatted disc as explained in the Acorn Master 512 User Guide in section 2.3 on page seven of Part Two, DOS Plus.

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