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#### 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:

Format | Sides | Tracks | Directory entries | Capacity
--- | --- | --- | --- | ---
D1 | Double | 80 | 128 | 716K
D10 | Double | 80 | 128 | 796K
D2 | Double | 80 | 256 | 712K
D20 | Double | 80 | 256 | 792K
D40 | Double | 40 | 128 | 396K
D80 | Single | 80 | 128 | 396K

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