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Creating the System Disks – Method 4

Method 4: Using both disks and a serial link

This is the method to use to make the 512 system disks if:

You have compatible-sized disk drives on your PC and your BBC Computer (both have 5¼" drives, or both have 3½" ones), but you cannot write the disk images on the PC. (It seems that some PCs just won't work with non-DOS disks, or you might have an old 40-track (360kb) disk drive on the PC.)

and also

You can link the PC and the BBC with a serial cable. (Click here for how to make one.)

There are several ways you could build the system disks if this is your set up. Of course, you could simply use Method 2, but that is very slow. It is much quicker to modify Method 3 and just copy a small amount of data to the BBC on the serial link then, when the Master 512 is booted up, transfer the rest on DOS floppy disks. How much you choose to move along the serial link is really up to you, but one option is described below. This one is a very minor modification of Method 3, merely allowing the serial link to take the place of the manual program entry that forms the initial part of that method.


The procedure described below begins by writing a Basic program across the serial link to the BBC Computer. You can use this program to copy a couple of other files from a DOS disk to a BBC disk. These will allow you to create a "short boot disk" – a disk which will allow the Master 512 to be booted up, but which contains only a minimal selection of utilities.

Once the 512 is up and running, all the other files that are normally on the boot disk can be copied to it. You can then use the 512 to format three disks in Acorn 800kb DOS format to become System Disks 2, 3 and 4 and copy the other files to them.

This is, admittedly, rather more indirect that necessary. See the introduction to Method 3 if you want to know more about why I have included these particular files in this package. It turned out that it was possible to adapt the method for this (Method 4) way of doing things with no further programming.

Important notes about the initial program

The DOS2BBC program was designed so that it could be typed in by users of Method 3. It has thus been made as simple as reasonably possible, and has been written to work with a particular set-up. If yours is different you will need to make a few minor alterations. These are all indicated with REM statements, and they are all in the procedure PROCsetup.

As it stands the program works on a Master, and reads files from a 360kb (5¼") disk in the second floppy drive (ie DOS drive B:) and writes them to files on a BBC disk in Drive :0. Things you may need to change are:

         If you are using a Model B or B+ rather than a Master then you must change five register locations and two other values. Make the changes in lines 290 to 330 and line 410 – all described in the REM statements. (The five floppy disk control registers are in a different place on the Master from where there are in the B and B+, and for one of them the control bits appear in a different place within the register itself. If you do not change these then the program will not work on the Model B or B+. (I think these values are all you need to change, but I have only tried the program on a Master so I cannot promise. Get in touch with me if it still doesn't work.))
    If you are using 720kb (3½") disks then, because these are 80-track rather than 40-track disks, you must change the value of step% from 2 to 1 in line 490.
    If you need to change which drives are being used, then make the alterations indicated in line 410 to change the source drive, and in line 450 give the correct (BBC) name for the destination drive. These cannot be physically the same drive, though the destination could be a hard disk.

To avoid unnecessary typing for Method 3 users, some features of the program are fairly crude. It ignores the file extension, for instance. The files have to be among the first 16 entries in the root directory. Also there is no error checking (other than what Basic will do automatically). If you use this program on a disk that does not contain the appropriate files, or isn't a DOS disk at all, then it will simply freeze. It is up to you to use it properly.

In detail

Note that this procedure was designed for use on a Master 512 fitted with two floppy disk drives. If your system has a hard disk and only one floppy drive then you will need to do some things slightly differently. All of these are noted in what follows.

You can create the Master 512 system disks from the resources provided here in the following way:

          Download the Method 3 & 4 Package onto the PC and unpack the Zip file.
    Make sure the serial cable is plugged into both machines (and that it is the right way up at the BBC end!)
    Select ADFS on the BBC. With the AFORM utility format two floppy disks in ADFS Large format. Label one of these "DOS-Plus Boot Disk" and the other one "Temporary ADFS Disk". (If you have a hard disk on your BBC then you will only need one floppy, the one that is to be the DOS-Plus Boot Disk. Temporary files can all be saved on the hard disk.)

Using the serial connection, copy the file DOS2BBC.TXT to a Basic program on the BBC Computer. To do this:


If your base machine is a Master, then enter:


and press <Return> then <Break>. (This sets the data pattern to "8N1" – you won't need to do anything on the Model B or B+ to achieve this because it is the default on those machines.)


From Basic on the BBC, running in native mode, enter:

*FX 7,4
*FX 2,1

to enable input from the RS423 port at 1200 baud. (The LISTO command is to tell Basic IV to strip off leading spaces.)


From a DOS command line on the PC, assuming DOS2BBC.TXT is in the current directory, enter:

mode com1: 1200,n,8,1
copy dos2bbc.txt com1:

then when the copying is complete (you will see the lines being written on the BBC screen) enter:

copy con: com1:
*fx 2,0

to re-enable the keyboard on the BBC.

Use com2: rather than com1: if that is where your serial cable is connected, of course.

    On the BBC again, SAVE the DOS2BBC program to the Temporary Disk.

If you prefer, perhaps if you already have serial transfer software set up, you could simply copy the DOS2BBC.TXT program as it stands to the BBC, and then *EXEC it to create the Basic program.

    If necessary edit the DOS2BBC Basic program to take account of your own set-up. (As it stands the program works on a Master and will copy two files from a 360kb DOS floppy disk in Drive B: and write them to a BBC disk in Drive :0.) See above, or the REMs in the program, for details.
    On the PC, format a 360kb (5¼") or 720kb (3½") disk, depending on the size of the compatible drives. (See below if there are problems with this formatting.)
    Copy the two files SHBOOT.PTI and WRPARTIM.BAS to this DOS disk you have just created.

Back on the BBC, place the Temporary ADFS Disk in the first floppy drive, and in the second floppy drive insert the DOS disk containing the two files SHBOOT.PTI and WRPARTIM.BAS. From here run the DOS2BBC Basic program. This will copy the two files onto the ADFS disk, stripping off the file extensions.

(If you have a hard disk and only one floppy drive, then put the DOS disk in the first floppy drive, and use the hard disk for your temporary files. Make sure you have edited DOS2BBC to read from the first drive.)

The program emits a "." for each cluster read, normally 1kb. (The SHBOOT.PTI file is nearly 200kb long, so the dots should continue for well over 4 lines.)

    Remove the DOS disk, and replace it with the (currently blank) disk labelled "DOS-Plus Boot Disk". Leave the temporary files where they are on Drive :0.
    If you have a hard disk on the BBC, then edit the WRPARTIM Basic program, now on the Temporary Disk. The second data item in line 100 must be the number of the floppy drive containing the disk that is to be the boot disk – ie 4 or 5, depending on which one you are using. If you have a twin-floppy-only system, then leave this value as 1. (The first data item is the file that is being written to it. There is no need to change this unless you are using a different drive than :0.)
    Run the Basic program WRPARTIM. It will write the file SHBOOT to become the first part of the DOS-Plus Boot Disk.
    Now put this Boot Disk in the first floppy drive. (It will need moving across if you have a twin-floppy system and have been following the above exactly. The temporary disk can now be forgotten about.)

Enable the 512 co-processor. (On a Master enter *CONFIGURE TUBE and press <Return>; just switch the co-processor on if it is an external one attached to a Model B or B+.)


Press <Ctrl-Break> to boot into DOS-Plus.

Once the machine has booted up you can look at the disk (with DIR) and you will see that, besides the system files and the command processor, it contains four other files: HDBOOT.SYS, HDISK.CMD, PCCE.COM and PKUNZIP.EXE. The first two of these are for hard disk users only (see next paragraph); PKUNZIP is the classic DOS program to unpack zipped file archives; PCCE is the "PC Compatibility Enhancer" which is necessary to allow this version of PKUNZIP (2.04g) to work on the Master 512.


If you have a hard disk, then enter:


and follow the instructions to create a bootable DOS hard disk partition. Once done, this will be Drive C:.


[This package is designed so that you can unpack the zipped files on the Master 512. If you prefer you could unpack them on the PC, then simply transfer the files across on DOS disks. This may require several transfers, especially if you are using 5¼" disks, but in that case you will not need to use PKUNZIP on the Master 512, and you will not need to use PCCE. Since these are not actually supplied with DOS-Plus, you could delete them before going any further.]

If you like to go ahead with unpacking the archives on the Master 512, then proceed as follows:




to launch the Compatibility Enhancer.

    On the PC copy the file M512_1D.ZIP to a DOS floppy disk. (You can use the same one as before if you like – you do not need the files on it any more.)

On the Master 512, use PKUNZIP to unpack the files in this archive to the DOS-Plus Boot Disk. (Note: PKUNZIP will unpack to the current directory. So select A: and enter:

pkunzip b:m512_1d

or whatever is appropriate if you have put the zipped file elsewhere. You may need to do some "shuffling" if you only have one floppy drive.)

The DOS-Plus Boot Disk is now complete.


Now enter:


to start the DOS-Plus disk management utility. Use this to format three disks in 800kb Acorn DOS format. (The program is menu-driven and very easy to use. The format you want is the second one in the list of formats.) These three disks will become System Disks 2, 3 and 4, so you might as well label them at this point.


The only remaining task is to unpack the other three principal archives onto these three disks. So:

       On the PC, copy M512_2.ZIP to a DOS floppy – you can continue to use the same one.
    If necessary, put PKUNZIP.EXE on this disk too. You can copy it on the Master 512 from the DOS-Plus Boot Disk you have created.

With this disk in Drive B: of the Master 512, and the blank 800kb disk that is to be System Disk 2 in Drive A:, at the A> prompt enter:

b:pkunzip b:m512_2 -d

noting the "-d" command tail, which must be in lower case and is necessary to make sure the directories are unpacked properly.

Alter the drive letters accordingly, of course, if the files are on different drives.

    Repeat the previous to unpack M512_3.ZIP to System Disk 3, and M512_4.ZIP to Disk 4. Note that if you need to reboot at any time during this process then you must run PCCE again before continuing or PKUNZIP will crash.
DOS-Plus Version 1.2

The Method 3 & 4 Package also contains the files for the older version of the DOS-Plus Boot Disk, with DOS-Plus Version 1.2 (actually 1.2a). You probably do not need this, but you might like to have it for interest, and there are rumours that a few programs will run on the older system but not on the newer Version 2.1 (though I have never come across one).

If you wish to create this then use the DISK utility again, but this time to format a disk in 640kb Bootable DOS format, and answer "No" when asked whether you want to make it bootable! Unpack to this disk the system files, which are in the archive M512_XS.ZIP. (These must be the first files on the disk. After you have done so then you may like to mark them as system files using the FSET utility from the Vn. 2.1 disk.) Finally unpack the remaining files from the M512_XD.ZIP archive.

Extra Utilities

The programs PCCE and PKUNZIP have been included on the short boot disk to enable the above process to be carried out. These two programs are not on the original boot disk. Delete them if you want a disk with only the original files on it.

Formatting double-density disks on a PC

To transfer data and programs between the Master 512 and the PC on disks, you will normally use DOS disks that both machines can read. These will be the standard double-density (DD) formats used by the PC, namely 360kb for 5¼" disks or 720kb for 3½" disks. Such disks are used in the procedure described above, for instance.

The Master 512 cannot use high-density (HD) formats (1.44Mb for 3½" disks and 1.2Mb for 5¼"). Make sure that the disks you are using are DD disks, formatted with the appropriate DD capacity.

Note that you cannot reliably format HD disks in DD sizes. You must use actual DD disks. (They are not commonly on sale now, but there are still a lot of them around.)

Note also, by the way, that all disks you intend to use on both machines must be formatted on the PC. The Master 512's formatting program does not work properly for 360kb and 720kb formats. (It is fine for the Master's own dedicated formats, of course.)

The following points may also be worth noting:


If your PC is running Windows XP or later, then you cannot format a floppy disk in one of the double-density sizes from the usual Format dialogue in Windows Explorer or My Computer. (You are not given these options.) To format a disk select "Start | Run..." and enter:

format <drive> /t:40 /n:9

to format a 360kb disk in the given <drive> (A: or B:). To format a 720kb disk change the 40 to 80.

    Sometimes disks will not work properly if they are formatted on a PC after being used with an Acorn format such as ADFS on the BBC. (This is because parts of the BBC formatting can be left over, and these confuse the PC.) If this is a problem, then the solution is to reformat them on the BBC in DFS (both sides) before formatting them again on the PC. Single density (DFS) disks appear totally blank to the PC, and it will treat them as "virgin" disks.

Downloadable Resources

      Method 3 & 4 Package:   This contains all of the files you need for creating the Master 512 system disks by this Method 4 or by Method 3. (This package was originally put together for people who need to use Method 3, but it works equally well in the manner outlined above.)

About the 512 | System Disks | Software | Index