

                                           RAMDOS MANUAL

                         http://www.cantrell.org.uk/david/tech/cpc/ramdos/
   
                             PDF/RTF/TXT Conversion by Transformer (2005)


                                           =============
                                           === INDEX ===
                                           =============


x Introduction                                       

x Simpleuse                                          
         o Start of day disc                            
         o Techie bits                                
                  - Writing a loader                   

x FORMATS.BIN program                                 
         o Change formats                             
                  - Available formats                 
         o Format a disk                               
         o Customise RAMDOS.BIN                       
         o Examine/alter DPBs                         
         o Copy disks                                 
         o Identify disk                              

x Gorydetails                                        
         o DPB/ALV addresses                          
         o Sector numbers for each format                
         o 'Sidedness'                               
         o Limitations of CAT                          

x Using with CP/M2.2                                   
         o Modify system tracks                        
         o CopyRAMDOS2.COM                           
         o Modify startup commands                     
         o Techie bits                                

x Using with CP/M+                                     
         o Simple use                                 
                  - CopyRAMDOS+.COM                  
                  - PROFILE.SUB                      
         o Patching CP/M+ for D20 discs                  
                  - Other formats                     
         o Directory size                             
x Using with Tasword                                   
x ROMDOS                                             
                          



                                            ====================
                                            === INTRODUCTION ===
                                            ====================


RAMDOS allows the use of an 80 track double sided second disc drive on the Amstrad
CPC series of computers under Amsdos (Amstrad Basic), CP/M 2 or CP/M Plus.

Most of the programs are unprotected so that they can be copied onto your discs easily.
The programs are encoded so that any illegal copies can be traced to their original owner.
[Bollocks - DC]                                              

The various programs on the disc allow the use of RAMDOS in the different programming
environments and other situations:                           

                      RAMDOS.BAS & RAMDOS.BIN  for use in Basic(Amsdos)

                                  RAMDOS2.COM  for use in CP/M 2.2

                                  RAMDOS+.COM  for use in CP/M Plus

                                  FORMATS.BIN  to format disks etc

                                  RAMDOST.BAS  to use with TASWORD 6128





                                              ===================
                                              ==== SIMPLE USE ===
                                              ===================


RAMDOS with Basic or Binary programs:              

Switch on Drive B, THEN switch on the computer and type:

RUN "RAMDOS" ENTER                                 

RAMDOS prompts you state the computer you are using and loads RAMDOS.BIN
accordingly. If the computer is an unexpanded 464 or 664, HIMEM is lowered by about 2K,
but if it has the extra 64K of memory, HIMEM is not changed. Discs for drive B can be
formatted using FORMATS (see below).               

The disc commands and BIOS calls work as normal with RAMDOS (ie SAVE, LOAD,
|ERA, |REN, |TAPE, |DISC, CALL &BC77 etc etc).     


Start of day disc:                                 

Files needed are: RAMDOS.BAS and RAMDOS.BIN. The Basic program is unprotected,
and can be loaded and saved as normal. The Binary program can be loaded by:

MEMORY &2FFF                                       
LOAD "RAMDOS.BIN",&3000                            
and saved by:                                      
SAVE "RAMDOS.BIN,b,&3000,&E00                      



Technical details                                  

RAMDOS.BIN occupies about &900 bytes, the bulk of which (about &800) can be
relocated to any address between &4000 and &BFFF or in any of the extra banks of
memory (ie banks 4-7), and a small portion of which (about &CO) must reside in &8000-
&BFFF. It is relocated by loading into &3000 then calling &3000 with the following
parameters:                                        

CALL &3000,@hm% [,bank,@hm.bank%]                  

The portion in square brackets is optional and is used to relocate the larger part of the
program into one of the extra banks of memory. If it is ommitted, the larger part of the
program will be relocated immediately below the smaller part. The variables hm% and
hm.bank% are the addresses below which the program will be relocated, and must be
defined before they are used. After relocation they are automatically updated to the
address immediatedly below the relocated program.  



Writing a Loader - Examples of alternative loading programs:

10 REM To relocate RAMDOS.BIN below HIMEM
20 IF HIMEM>&7FFF then hm%=HIMEM-2*-&8000 ELSE hl%=HIMEM
30 MEMORY &2FFF: LOAD "RAMDOS.BIN",&3000
40 CALL &3000, @hm%
50 MEMORY hm%: REM set HIMEM just below Ramdos

10 REM To relocate RAMDOS.BIN to bank 7 and below HIMEM
20 IF HIMEM>&7FFF then hm%=HIMEN-2*-&8000 ELSE hl%=HIMEM
30 bank%=7
40 hm.bank%=&7FFF: REM address in bank 7
50 MEMORY &2FFF: LOAD "RAMDOS.BIN",&3000
60 CALL &3000,@hm%,bank%,@hm.bank%
70 MEMORY hm%: REM set himem just below Ramdos

The loading program RAMDOS.BAS relocates RAMDOS.BIN to just below HIMEM or, if
extra banks are available, to the top of bank 7 and to the area of memory used by Tone
Envelopes nos. 3-15. If you wish to use these Tone Envelopes, then either relocate the
whole of RAMDOS.BIN below HIMEM in the normal RAM or relocate the small second
part into a different area. The first option is the easier, because you just need to tell
RAMDOS.BAS that you are using an unexpanded 464 or 664. The second option requires
that you write an alternative loading program, such as no.s 2 or 3 above.

The bank number at which the majority of the program is held is found at &BE3F, in the
form of &C0+bank number. In the ROM version this is the ROM position, and in RAMD0S2
this has the value of 2.

If RAMDOS is relocated into one of the extra banks of memory, the 2K buffer used by CAT
and LOAD is fixed immediately below RAMDOS, occupying roughly &7000-&7800. This
buffer normally resides immediately below HIMEM but this means that the buffer would be
in danger of over-writing RAMDOS. This is because the bank used by RAMDOS is
switched in to occupy &4000-&7FFF whenever disc functions are used, so that the 2K
buffer over-writes this bank whenever HIMEM is between &4800 and &8800. To avoid this,
the buffer is fixed to a permanent position occupying the 2K immediately below RAMDOS.
The position of this permanent buffer address can be changed by poking a new value into
&BE3B/C after RAMDOS has been initialised. A value of zero will make the buffer lie
immediately below HIMEM as normal.




                                       ===========================
                                       === FORMATS.bin PROGRAM ===
                                       ===========================


Install RAMDOS then:                                                                 

RUN "FORMATS"                                                                        

FORMATS invites you to:                                                              

    1. View or Change format of a drive                                              
    2. Format a disc                                                                 
    3. Customise RAMDOS.BIN                                                          
    4. Examine the Disc Parameter Blocks                                             
    5. Change the Disc Parameter Blocks                                              
    6. Catalogue disc                                                                
    7. Change USER number                                                            
    8. Disc Copy                                                                     
    9. Test format of Drive B                                                        



Change formats                                                                       

This allows the computer to be set to read and write different disc formats. Before  
formatting a disc, you will need to use this function to set the drive to the format which you
wish the disc to have.                                                               

The formats available for drive B are:                                               

                         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
                         O                            Other formats               

The formats available for drive A are:                                               

                         Format    Sides  Tracks  Directory entries   Capacity             

                         D(Data)   Single 40      64                  178K
                         S(System) Single 40      64                  169K
                         P(PCW)    Single 40      64                  173K
                         B(Buffer)            used for copying a 5.25" disc        
                         O                         Other formats              



It is better to chose one format for all your discs. Format D1 provides maximum
compatibility with software such as disc editors, while D10 provides maximum storage
space. D20, which sacrifices a little storage space to provide twice as much directory
space, is the default format, but this default can be changed by using function 3. To use
different formats with the CP/M versions, see the relevant notes below.

The Buffer format is needed for function 8 (see below). The "Other" option allows you to
define your own format. within sensible limits.
When using 256 directory entries, never allow more than 140 files per User group. For
further information, see the Technical Details below.



Format a Disc                

The disc will be formatted according to the current format set for that drive. You are
reminded of the current formats and asked which drive you wish to use for formatting. If
the current format is not the format you wish to put on the disc, then press N (for None),
which will return you to the menu, and use function 1 to change the current format.
Error messages such as 'Disc not ready' may occur on drive B, because it takes a little
time for the head to move from track 80 to track 0. If this occurs, press 'R', (for Retry) to
continue formating. An error message referring to Drive F means Drive B, side 2.



Customise RAMDOS.BIN         

This allows you to change the default format used by RAMDOS for drive B. It loads
RAMDOS.BIN, alters the Disc Parameter Block with the values of the current format for
drive B, and then saves this new version.



Examine                      

These functions are for the specialist. The DPB values represent the current formats which
are set for the drives. They are recalculated and updated when function 1 is used to
change the format, but function 5 allows you to set these values independently.

                            WARNING. Setting these values wrongly can
                           seriously damage the health of your disc drive!



Disc Copy                    

This function is for copying a disc in drive B. In order to cut down the number of disc
swaps to a minimum, a Buffer disc is used in drive A which can hold one quarter of the
data on a 5.25" disc. The destination disc must have the same format as the source disc
BEFORE copying, and the disc in drive A must have the 'Buffer, format.



Test disc format

This function will identify the format of any disc which has been formated using
FORMATS. The first track is searched for all the sector numbers present, and the first five
track numbers on each side are identified. This information enable most non-standard
formats to be identified.




                                           ====================
                                           === GORY DETAILS ===
                                           ====================


DPB/ALV addresses                                                     

The Disc Parameter Blocks (DPBs) of both drives, the Allocation Vector of drive A (ALVA -
a representation of disc usage) and the Check Sum of drive A (CKSA - a representation of
directory usage) remain at their normal addresses but the ALVB is located at &BE00 and
the CKSB at &BEC0. These CKSs and ALVs allows for a maximum of 184K and 64
directory entries in drive A, and 800K and 256 directory entries in drive B. If larger values
are required then the CKS or ALV concerned will have to be moved.     



Sector numbers for each format                                        

The different formats are recognised by their sector numbers. The standard formats for
drive A use the same sector numbers as normal. The first sector numbers of the different
formats are:                                                          

                                              Drive A    PCW    &01         
                                                         Buffer &11  
                                                         System &41   
                                                         Data   &C1   
                                                         Other  &81  
                                              Drive B    D1     &01
                                                         D10    &11   
                                                         D2     &21
                                                         D20    &31   
                                                         D40    &51   
                                                         D80    &71   
                                                         O      &81



'Sidedness'                                                           

Double sided discs are assumed to be single step and flip-sided, but the sidedness and
stepping can be changed by function 1, requesting the "Other" format types.
Sidedness of three kinds are recognised:                              

- Flip-sides: Logical tracks 0-159 on alternate sides of the disc,
  from physical track 0-79.                                                                         
- Up and Over A: Logical tracks 0-79 on side0 of the disc. and logical
  tracks 80-159 on side 1.                                                                  
- Up and OverB: this is the reverse of normal UpandOver on the second side,
  so that both sides are identical.                                              

The table below may (or may not) make this clearer. If in doubt, use Flip sides, which is
the fastest and commonest format. If you are trying to read a strange disc and Flip sides
produces nonsense, then try Up and Over A, which is much more common than B.         

                              Logical     Physical     
              Sidedness       track nş    track nş      Side  
    
             Flip sides           0            0          0
                                  1            0          1
                                  2            1          0
                                  3            1          1
                                159           80          1

           Up and Over A          0            0          0
                                  1            1          0
                                 79           79          0
                                 80           79          1
                                159            0          0

           Up and Over B          0            0          0
                                 79           79          0
                                 80            0          1
                                159           79          0


Sidedness and stepping are recorded at &BE3A and &BE3D for drive A & B respectively. 

They are set to the default values of 0 and &8F on initialisation and can be changed by
poking new values. The byte value is worked out as follows (where x is any bit value):

    &Fx = 40 tracks single stepping                                                      
    &8x = 80 tracks single stepping                                                      
    &4x = 40 tracks doubles tepping                                                      

    &xF = Double sided Flip sided                                                        
    &x8 = Double sided Up and Over A                                                       

    &x4 = Double sided Up and Over B                                                       
    &x2 = Single sided.                                                                


    One powerful facility of RAMDOS is the ability to read or format tracks whose logical
    track numbers are different from their physical track numbers. This allows the creation
    of protected discs which can only be read with RAMDOS. The physical track number is
    position of the track on the disc (0-39 or 0-79), and the logical track number is the
    number encoded into the sectors when formatting. The offset is the difference between
    them. This offset must be poked into &BE39 for drive A and &BE3? [heretheoriginal
    documentationisunclear-DC]for drive B. The default value is zero, which allows the
    reading of all normal formats.

The formats D10,D20,D40 and D80 hold more data because they use 10 sectors per track,
instead of the normal 9.



Limitations of Cat

The number of directory entries is not always the same as the number of files which can
be saved when large files are used, because every 16K requires an extra directory space.
The maximum number of files which can be CATed is 140, although any number of files
can be DIRed. This is because the buffer for CATing is only 2K long and although this
could be enlarged it could cause compatibility problems with other software. Therefore it is
best to allocate different types of files to different User groups when a large number of files
are kept on a disc. This should also make the disc more organised and easier to use.




                                      ============================
                                      === RAMDOS with CP/M 2.2 ===
                                      ============================


Before you can use RAMDOS with CP/M 2.2 you will need to modify your system discs
(see Start of Day Disc below). Modified discs can be used as normal, with or without
RAMDOS, although the TPA will be reduced to 42K.

Discs for drive B can be formatted by using FORMATS (see above). The default format is
D20 but any of the standard formats can be read.

When you have modified your discs for drive A and have formatted some discs for drive B,
RAMDOS is installed by:                   

|CPM                                      
RAMDOS2                                   

Or, if you wish to use another format, eg D10, type:

RAMDOS2 D10                               

Some CP/M 2.2 programs cannot be used with an 80 track second drive, either because
they are written for drive A only (such as FILECOPY, DISCCOPY, DISCCHK) or because
they assume that drive B has the same format as drive A (such as COPYDISC, CHKDISC,
FORMAT).                                  

To move files, use PIP (see your Amstrad manual), eg to copy all the contents of drive A to
drive B use:                              

PIP B:.A:*.*                              



Start of day disc                         

To modify the system tracks:              

Put the CP/M 2.2 System Disc in drive A, with Side 1 uppermost, and type:

|CPM                                      
MOVCPM 170 *                              
SYSGEN *                                  

Put the disc to be modified in drive A when prompted. Press any key.



Copy RAMDOS2.COM                          

To copy RAMD0S2.COM onto a Start of Day disc, put the CP/M 2.2 System Disc in drive
A with Side 1 uppermost, and type:        

|CPM

FILECOPY RAMDOS2.COM

Put the RAMDOS disc in drive A when prowted for the Source Disc.

Put Start of Day disc in drive A when prompted for Destination Disc.

Follow the same procedure to copy PIP.COM (on the Utilities disc).



Modify Starup Command

SETUP can be used to call RAMDOS2 automatically whenever |CPM is used (see
Amstrad manual). Add into the Initial Command buffer:

RAMDOS2^M

A different default format can be installed by adding the new format to the Initial Command
buffer, eg:

RAMDOS2 D10^M



Technical details

MOVCPM moves the CCP down in memory to make room for RAMDOS. The main
jumpblock is moved from &AD00 to &A400.

The addresses for the CKS and ALV of drive B, the sidedness and track offset of both
drives are the same as for RAMDOS.BAS.





                                      =========================
                                      === RAMDOS with CP/M+ ===
                                      =========================


Put any disc in drive B, and type:         

|CPM                                       
Type RAMDOS+ D20                           

If a disc is not in drive B when CP/M + is loaded, then drive B will not be logged in.
The discs for drive B can be formatted by using FORMATS (see above). DISCKIT3 cannot
be used to format a double sided 80 track disc. The standard formats (D1, D10, D2, D20,
D40, D80) can be called directly by typing 

RAMDOS+ D10 or RAMDOS+ D2 etc.             

If RAMDOS+ is entered without a format, you will be prompted for one of these formats or
for "Other" formats. The "Other" option enables you to change the Disc Parameter Blocks
directly.                                  



Start of day disc                          

File needed is RAMDOS+.COM. This can be copied by using PIP.
To copy RAMDOS+.COM onto a Start of Day disc, first make sure that if drive B is
connected, do NOT put a disc in it; then put the CP/M + System Disc in drive A, with Side
1 uppermost and type:                      

|CPM                                       
PIP A:=B:RAMDOS+.COM                       

Put the RAMDOS disc in drive A when prowted for the 'Disc for B', and put your Start of
Day disc in drive A when prompted for the 'Disc for A'



PROFILE.SUB                                

The command RAMDOS+ D20 can be put in a PROFILE.SUB file on your start of day disc
so that it is called whenever CP/M is initialised. See your manual or the Help file on your
CP/M + disc.                               



Patching a CP/M + disk                     

The following instructions show how to reconfigure the CP/M + on your Start of Day Disc
so that it can access Drive B without calling RAMDOS+. Do not reconfigure your
original System Disc.                      

These instructions are for use with a single disc drive, and it may be less confusing if you
disconnect drive B while reconfiguring your disc.

Reset your computer by pressing CTRL-SHIFT-ESC simultaneously. Put your copy of the
System Disc in Drive A, with Side A uppermost.

Type in the commands which are underlined, and follow the instructions in square
brackets. The other words are the responses made by the computer.


 You carry out the following procedure at your own risk. Although I have checked this data,
you should be aware that OCR errors may have slipped through, and entering incorrect data
                          will bugger things reallyspectacularly.


||CPM                               [Enter]
[Turn the disc over. Press any key.]  
A> B:SAVE                           [Enter]
A> B:SID C1OCPM3.EMS                [Enter]
CP/M 3 SID - Version 3.0              
?                                     
£ G100 [Put the disc to be reconfigured
    in drive A and press ENTER.]      
CP/M 3 SID - Version 3.0              
NEXT MSZE PC END                      
6500 6500 0100 D2FF                   
£ S1087                             [Enter]
1087 32        C3                   [Enter]
1088 DD        E2                   [Enter]
1089 B0        0E                   [Enter]
108A C9        X                    [Enter]
?                                     
£ S10A2                             [Enter]
10A2 FF        32                   [Enter]
10A3 FF        DD                   [Enterl
10A4 FF        B0                   [Enter]

[Continue typing the following numbers,
    pressing ENTER after each]        

21 E5 03 11 7F FF 01 1B 00 ED B0 C9   
10B1 FF        X                    [Enter]
?                                     
£ S5A5                              [Enter]
05A5 FF        28                   [Enter]
05A6 FF        00                   [Enter]
05A7 FF        04                   [Enter]

[Continue typing the following numbers,
    pressing ENTER after each]        
0F 00 8F 01 FF 00 F0 00 20 00 00 00   
02 03 01 50 0A 31 00 02 09 10 60 FF   

05C0 32        X                    [Enter]
?                                             
£ SF1A                              [Enter]
0F1A 79        CD                   [Enter]
0F1B F6        F8                   [Enter]
0F1C 20        01                   [Enter]
0F1D 23        X                    [Enter]
?                                             
£ S3B8                              [Enter]
03B8 FF        79                   [Enter]
03B9 FF        E6                   [Enter]
03BA FF        03                   [Enter]
03BB FF        F6                   [Enter]
03BC FF        20                   [Enter]
03BD FF        C9                   [Enter]
03BE FF        X                    [Enter]
?                                             
£[Press CTRL & C together]                    
CP/M 3 SAVE - Version 3.0                     
Enter file (type RETURN to Exit):             
    C10CPM3.EMS                     [Enter]
Delete C10CPM3.EMS? Y               [Enter]
Beginning hex address 100           [Enter]
Ending hex address 6500             [Enter]
A>                                            
The disc is now reconfigured.                 



Technical details                             

This patch enables CP/M + to recognise a 5.25" drive B. It can only be used on CP/M + on
the CPC, and not on CP/M 2.2 Plus on the PCW. 

The DPB values are the ones poked into &5A5-&5BF. The values above are for the D20
format. If you wish to have a different format, use the following values:

D1:  14 00 04 0F 00 67 01 7F 00 C0 00 20 00 00 
     00 02 03 01 50 09 01 00 02 2A 52 60 FF  
D10: 28 00 04 0F 00 8F 01 7F 00 C0 00 20 00 00
     00 02 03 01 50 0A 11 00 02 09 10 60 FF  
D2:  24 00 04 0F 00 67 01 FF 00 F0 00 20 00 00 
     00 02 03 01 50 09 21 00 02 2A 52 60 FF  
D20: 28 00 04 0F 00 8F 01 FF 00 F0 00 20 00 00
     00 02 03 01 50 0A 31 00 02 09 10 60 FF  
D40: 28 0O 04 0F 00 C7 00 7F 00 C0 00 20 00 00
     00 02 03 01 28 0A 51 00 02 09 10 60 FF  
D80: 28 00 04 0F 00 C7 00 7F 00 C0 00 20 00 00
     00 02 03 00 50 0A 71 00 02 09 10 60 FF  



Directory Size - PLEASE NOTE - 128 entries only!

Because CP/M + uses a hash table for quick reference to the directory of the disc, this in
most cases limits the number of directory entries to 128. This is so for PIP under CP/M +.




                                  ================================
                                  === RAMDOS with TASWORD 6128 ===
                                  ================================


RUN "TASWORD"                      
- go into Basic then               
RUN "RAMDOST"                      

RAMDOST loads RAMDOS.BIN into the text area which is reduced by 2K to about 62K.

If Qualitas 464 is being used, then run Qualitas first, return to Basic and run RAMDOST.

If Qualitas Plus is being used it is necessary to make a slight alteration to the Qualitas
loader programs. The changes to Qualitas Plus version 1 are as follows:

QTW6128.BAS                        

200 RESTORE 210;n=48784:FOR i=n TO n+19:READ j:
      POKE i,j:NEXT i              


QUAL128.BAS & QM02.BAS             

170 RESTORE 180:n=48784:FOR i=n TO n+32:READ j:
      POKE i,j:NEXT i              


For Qualitas Plus version 2, change the statement

n=48664                            
(or similar) to                    
n=48784                            
in QUAL128, QPM128, QTW6128 and QMO2 (the line number containing the value of
n                                  
varies according to the loader program).



Start of day disc                  

Files needed are RAMDOST.BAS, and RAMDOS.BIN. The Basic program is unprotected
and can be loaded and saved as normal. The Binary program can be loaded by:

MEMORY &2FFF:LOAD "RAMDOS.BIN",&3000
and saved by:                      
SAVE "RAMDOS.BIN",b,&3000,&E00     



Technical details

RAMDOST loads RAMDOS.BIN into the top of bank 7, which is the top of the text area in
Tasword 6128. The text area available in Tasword is reduced so that it is not possible to
over-write RAMDOS by filling the text space.

Qualitas also loads part of its program into bank 7, but it cannot be relocated, so Qualitas
must be run first. RAMDOST will then relocate RAMDOS below Qualitas. Qualitas further
reduces the text area available.

The 2K buffer area is not changed by RAMDOST, because TASWORD sets a new
permanent buffer of its own.





                                         =========================
                                         === 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 in the CP/M 2.2 and CP/M+ sections 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   


(END)