The BBC Master 512

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Creating the System Disks – Method 1

Method 1: Writing the disks on a PC

To use this you must have compatible sized disk drives. Note also that all the drives you are using must be 80-track double-sided ones. (So a 360kb-only drive on the PC will not do, since it will have only 40 tracks. If you are using 5¼" disks, then the PC drive must be a 1.2Mb one, which will have 80 tracks. Note: This is the drive not the disks. Do not use HD disks.)

If you have these, then you may as well try using this method of creating the system disks, as it is far simpler and quicker than any of the others. Some PCs can be made to write the Master 512 format disks. Others, it seems, cannot. I know of no way of finding out except by making the attempt! So have a go! If it succeeds, then you have your system disks. If it fails, then you will simply have to use one of the other methods.

You can download the Method 1 Package from this site. By far the largest part of this package consists of disk images of the four system disks, each one saved as a single file.

In addition to the image files, you need software that can cause the PC to write them to floppy disks. There are a couple of simple and easy-to-use programs included in the package (one for 640kb and one for 800kb), but if you want something more flexible, or if the enclosed programs do not work on your PC, then you could use something more sophisticated such as OmniDisk (for DOS or Windows up to and including Me) or OmniFlop (for Windows NT, 2000 or later).

Important Note about the Boot Disk Image

Some, possibly most, disk writers will not write the image file M512_1.IMG in the correct form for it to work as a Master 512 boot disk. They may appear to write the image to a disk, but the resulting disk will not boot the machine. For such a program use the file M512_1.ADL instead of M512_1.IMG.

This problem arises because the logical sector and track order of an Acorn 640kb disk is different from many other disk formats. This is explained in more detail on the Disk Formats page. The logical order of the tracks of an Acorn 640kb disk, and so of the Master 512 boot disk, is for all of the tracks on Side 0 of the disk to come first, followed by all of the tracks on Side 1. The file M512_1.IMG is laid out like this. However in almost all other double-sided floppy disks, including all DOS disks, Track 0 of Side 0 is followed by Track 0 of Side 1, then Track 1 of Side 0, and so on, alternating between sides for the whole disk. A lot of disk writing programs will assume this is the way they need to interpret any disk image. For such a disk writer, the tracks are laid out correctly in the file M512_1.ADL.

In detail

The procedure to follow is this:

			Download the package and unzip the files.
			Using the BBC Computer in native mode (ie as a normal BBC Computer with the 512 co-processor turned off) format a disk in ADFS Large format using the ADFS disk formatter AFORM. (You must have ADFS on the BBC to be able to use the 512 at all.)
			Insert this disk into the PC and, using WRIMG640 or else one of the other image writing programs mentioned above, write to the disk the file M512_1.IMG (or M512_1.ADL – see "Important Note about the Boot Disk Image" above). This is now your DOS-Plus boot disk. (See below for notes about how to use the enclosed image writers.)
			Enable the co-processor on the Master 512 and, using the boot disk you have just created, boot up DOS-Plus. (Enable it with *CONFIGURE TUBE on a genuine Master with internal co-pro; just switch it on for an external one on a Model B/B+. Then with the disk in the first drive, just press <Ctrl-Break>.) [If it doesn't boot, try the alternative image.]
			Enter DISK to start the DOS-Plus disk management program. Use the program to format three more disks, this time in 800kb Acorn DOS format. (The program is menu driven and very easy to follow. The 800kb format is the second one on the list of formats available.)
			Back to the PC, and this time using WRIMG800 (or one of the other programs), write the files M512_2.IMG, M512_3.IMG and M512_4.IMG – one to each of these three disks you have just formatted. These are system disks 2, 3 and 4 (obviously!)
			Label the disks!

Using the enclosed disk image writers

The Method 1 Package includes two very simple DOS-based programs to write disk images for Master 512 format disks on a PC. These are called WRIMG640.COM (for 640kb disks) and WRIMG800.COM (for 800kb disks). They will not work on all PCs, but they are very easy to test out.

You can try using these from within Windows, using an MS-DOS command prompt box, or indeed from "Start | Run...", and you may succeed. However the programs seem most reliable when the machine is booted into a genuine DOS environment, and certainly they do not run well from within Windows XP or later.

At the DOS prompt, with everything in accessible directories, just enter:

WRIMG640 <filename> /A

to write <filename> to a (formatted) 640kb disk in Drive A:. Use "/B" instead of "/A" to write to Drive B: and use WRIMG800 to write to an 800kb disk.

Note that WRIMG640.COM does not work well on disks formatted as 640kb with the Master 512's DISK program (and the resulting disks are slower anyway). Always format 640kb disks in ADFS using AFORM on the native BBC Computer.

Using the images in an emulator

The included disk image files can be used to run an emulated version of the Master 512. If you are using BeebEm, then for the boot disk you will have to use one of the alternative, interleaved images (M512_1.ADL for DOS-Plus Vn 2.1, or M512_X.ADL for DOS-Plus Vn 1.2a). This issue does not arise with disks 2, 3 and 4.

Downloadable Resources

Method 1 Package:

This contains four disk images, one for each of the Master 512's system disks. (In reality there are seven images here, because there are four different versions of the boot disk file. These are images for DOS-Plus Versions 2.1 and 1.2a, both as true images and as alternative (interleaved) images. In addition the package contains the two simple image writers.

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