RAMDOS manual


How to use ROMDOS

The rom may be plugged into any standard rom board in any position between numbers 1 and 6 inclusive (ROMDOS cannot be used without the AMSDOS rom no. 7). ROMDOS should, however, be positioned below any rom that uses a standard AMSDOS command in a bar command form (e.g.|CAT used by UTOPIA), as such programs could assume that the B: drive is a 40 track single sided drive similar to the A: drive. No bar commands are necessary to access ROMDOS from BASIC as ROMDOS will automatically recognise the six formats for drive B: listed below.

In order to format discs up to 796K, a program called "FORMATS.BIN" is needed. This is supplied on the RAMDOS disc and instructions for use of the formatting program may be found on pages 5 & 6 of this manual. The formats which are automatically recognised are as follows:

FormatSidesTracks Directory
entries
Capacity
D1Double80128716K
D10Double80128796K
D2Double80256712K
D20Double80256792K
D40Double40128396K
D80Single80128396K

ROMDOS does not affect CP/M and the RAMDOS disc contains the necessary programs required in order to recognise the drive B formats. Full details of how to reconfigure a copy of your systems disc may be found on pages 9 or 10 of this manual. Note that a disc must be in drive B when |CPM is called in order for drive B to be logged in. Discs for drive B cannot be formatted with FORMAT.COM or DISCKIT3 because these programs assume that drive B is identical to drive A. Some other programs cannot be used because they are written for only one drive (such as FILECOPY, DISCCOPY or DISCCHK).

Technical details

HIMEM is not altered and all Basic commands, BIOS calls, and CP/M commands work as normal. The IBM format in drive A is replaced by the PCW format.

ROMDOS replaces the action of Rom 7, although for copyright reasons the original Rom 7 must be present. This leaves all the memory above HIMEM exactly as normal except: The ALV of drive B is now at &BE00, with room for 800K. The CKS of drive B is now at &BEC0, with room for 256 directory entries.

The different formats are recognised by their first sector number:

Drive A
  • PCW = &01
  • System = &41
  • Data = &C1
Drive B
  • D1 = &01
  • D10 = &11
  • D2 = &21
  • D20 = &31
  • D40 = &51
  • D80 = &71