Web Hosting by Netfirms | Free Domain Names by Netfirms

Microdos is an extension of AMSDOS^©, which allows the use of an 80 track second disc drive on the Amstrad CPC and CPC Plus computers. If your drive has a side-select switch then you will be able to access both sides of the disc. If you have a drive switch cable then all the advantages of the 80-track drive will be available on drive A.

The programs are unprotected so that you can make working copies.

PLEASE NOTE. you MUST not give or sell copies to anyone else; this is THEFT.

The programs on the disc are:

MICRODOS.BAS the main operating system

MDRSX.BIN the binary code for the RSX’s

BIGB.COM the patch for CP/M with 9 sector discs

BIGB10.COM the patch for CP/M with 10 sector discs

MICRODOS IN NORMAL USE

With drive B connected and switched on, switch on the computer, insert the system disc, and type:

RUN 'MICRODOS' <enter>

HIMEM is lowered by about 600 bytes to make room for the RSX code.

This remains in the computer till you switch it off or reset it.

SYMBOL AFTER is changed to 256 before lowering HIMEM so that you can set it to whatever value you wish in your programs.

Microdos includes an option for formatting discs to 80 tracks with either 9 or 10 sectors per track.

All AMSDOS commands and operating system calls work as normal, and all programs which obey AMSOFT’s rules will also work, e.g. PROTEXT and MAXAM.

Facilities have been included for Multiface users to save programs on to the first 40 tracks of 80 track discs on either side, and use the second group of 40 tracks for other programs, using a separate directory.

MICRODOS IN DETAIL

On running Microdos you will be presented with a menu of choices:

1. View or change format of a drive
2. Format a disc
3. Check a disc – all sectors or find format only
4. Short instructions
5. Exit from program

All keyboard input has been made as easy as possible; usually only one keypress is needed for any option. The ESCAPE key has been disabled to prevent accidents, but if you really need it, pressing CONTROL+ESCAPE together has the desired effect; pressing ESCAPE on its own will take you back to the opening menu.

• 1. View format of a drive
  This tells you what each drive is currently set for and allows you to select 80 tracks on either drive, with either 9 or 10 sectors per track. We suggest that you DO NOT ALTER the settings for drive A unless you have a cable that allows you use your 80-track drive as drive A.
  Selecting 10 sectors will give you 400 Kbytes on each side of the disc, with 9 sectors giving 360 Kbytes. Both figures will be reduced by 2 Kbytes if you have 64 directories and by 4 Kbytes if you have 128.
  If you have a Multiface you will need some discs with 9 sectors (see later) but if not you will probably stick to the larger format.

• 2. Format discs
  This option formats a disc in either drive using the current format settings for that drive. Make sure you have them set the way you want before formatting. If they are wrong you can get out by pressing 'N' or ESCAPE. Remember that formatting a disc erases all information on it.
  Technical note: 9 sector discs have the first sector number ∓mp;C1, the same as 40 track 9 sector data format. This is to ensure compatibility with Multiface. 10 sector discs have the first sector number ∓mp;71, the same as ROMDOS/RAMDOS D80 format.

• 3. Check disc
  This option will identify the format of an unmarked disc and will then ask if you wish to do a full sector check. If you are not sure of the quality of your discs it is a good idea to check them after formatting, especially if you use cheap bulk discs. All faulty sectors will be listed. If there are any you should reformat the disc and check it again – if still faulty, return it.

• 4. Instructions
  You will be given a shortened version of this booklet in case you forget what you are doing.

• 5. Exit from program
  You should use this option rather than CONTROL+ESCAPE so that the colours and key definitions are returned to normal.

THE RSX’s

Once these are installed you can check the settings of the currently selected drive and change them without reloading MICRODOS.

If you type the command without a parameter you will be told the current setting; type it with a parameter and this becomes the new value.

E.g. |tracks will tell you whether your drive is set for 40 or 80 tracks.

|tracks, 80 will set it to 80 track, 9 sector format

|sectors,10 will than set it to 10 sector format.

N.B. This will not work on a 40-track drive

|files sets the number of directories to 64 or 128.

Once you have set the value for a particular disc you should not use the other value, as this would result in files on track 1 being corrupted, or half of your directory being lost.

|part1 and |part2 switch between the first and second groups of 40 tracks. These are for users of Multiface

NB the "1" and "2" are part of the command, NOT PARAMETERS. Do not send a "|part2" command to a 40 track drive, as this will try to send the head carrier on to track 41. As this does not exist it could cause permanent damage to the drive.

MICRODOS with CP/M Plus

First you will need to copy the two files BIGB.COM and BIGB10.COM on to your working CP/M disc. Do this with PIP or any other file copier. Put a disc in drive B and type "|cpm" <enter>. Once the A> prompt appears type "BIGB" <enter> if you wish to use a 9 sector disc, or

"BIGB10" <enter> to use a 10 sector disc.

Both these programs change the CP/M parameter block in the same way that the Microdos programs change the AMSDOS block.

You could automate this process by putting the BIGB or BIGB10 command into the PROFILE.SUB file on your CP/M disc, as follows.

Working in Basic, not CP/M, and with side 1 of your working CP/M disc in drive A, type "|ERA, PROFILE.SUB"<enter>

Now type in this program:

10 open out "profile.sub"

20 print #9, "setkeys keys.ccp"

30 print #9, "language 3"

40 print #9, "bigb10"

50 closeout

Now RUN this program and the new PROFILE.SUB file will be created for you. This will automatically set drive B to be 80-track, 10 sector every time you enter CP/M. If you would rather have 9 sector format, change line 40 to <print #9, "bigb">

MICRODOS WITH MULTIFACE

The Multiface tape-to–disc copier will only use 9 sector discs, and only 40 tracks. This is because the device resets the disc parameters before every save. It has to do this because some tape programs overwrite the disc parameter blocks. Normally it will save to drive A, but it is possible to save to drive B by using "B:" as the first 2 characters of the file name when saving to disc (e.g. b:game)

You must use discs, which have been formatted with 9 sectors per track by the format option of Microdos.

You should reset the computer (CONTROL+SHIFT+ESCAPE) before loading the game from tape; you can save the game to side A or B of the B disc by using the side select switch. You should reset again and type |B before re-loading the game from disc.

As Multiface can only use tracks 0 to 39, tracks 40 to 79 are available for any other files. This is where you use "|part2"; this command tells the computer that the first 40 tracks are reserved, and creates a new directory on track 40 , effectively splitting each side of the disc into two separate 40 track discs , each with 178K free.

If you want to see what is on the Multiface part of the disc use "|part1: cat", and "|part2" to get back to the second half of the disc.

'to go to Index page' 'to return to linkspage' 'go to top of page'