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C-128 Compatibility
By: Carl F Howard
    [CHUCK.WAGON]
     09-19-1987
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     This   is   an    article   on   the   aspects   of   compatibility   of                  
the   C-128  and other operating systems and software available to facilitate 
the importing and exporting of data. This article centers on the CP/M mode of 
operation although the discussion will cover the various modes of the C-128 
as well.
                                                                            
     Even though  the C-128 utilizes 8-bit CPU's it's diversity as a personal 
computer for home and small business purposes is one of it's main Assets, and 
I am  sure many new users of the machine aren't even aware of the  capacities 
available to them.  Aside  from  playing your favorite games in C-64 mode the 
native 128 80 column capabilities allows much convenience for the use of pro-
ductivity applications to the new user. 

     There is already a wide base of Word Processing,  Data Base and Spread  
Sheet Software available for use.  Additionally by utilizing the CP/M mode of 
operation  users can take advantage of Business Applications and a huge  base 
of public Domain Software as well.  Also, it is possible to use your C-128 to 
process  data brought home from the office or school which was created on  an 
MSDOS machine.  This  article  will  help  you become  aware  of the  various 
different  disk  and data type formats and the software available to  convert 
data for your particular application.

     First  it is necessary for the new user to understand a little about the 
way  information is stored in the commodore computer and how it differs  from 
other types of computers used in the U.S.  As you are aware all data utilized 
by  a  computer is essentially processed in binary numbers in  the  forms  of 
zeros  and  ones.  This  represents  the on and off state  of  an  individual 
transistor switch in the intergrated chips of your computer.  This is  simple 
enough  as far as it goes but how does the computer know when you press a key 
on the keyboard what your pressing and what it means.

     Well  each  key  has a numeric value assigned to it.  The value  can  be 
expressed in Decimal,  Hexadecimal or binary form. And it is this value which 
is converted to a binary number that allows the computer to distinguish  what 
key is being pressed and what it means. Most computers used in the U.S. use a 
standard code called ASCII which assigns a value of decimal 1 to decimal  128 
to  characters used by them.  Commodore in their unique wisdom however  chose 
not  to  use  this  standard an developed a character  set  unique  to  there 
machines  using  decimal codes 1 to 256.  So in order to use data created  by 
other  machines it is necessary to convert it too PETASCII code a form  which 
your Commodore computer can understand.

     Aside from the data differences Commodore also chose to use a  different 
way of storing  information on their floppy disk as well. Mostly their reason 
for this was to build a cheaper disk drive. They use GCR format as opposed to 
MFM  format for the rest of the U.S.  computer industry.  I won't go into the 
difference  here  but,  it is nice to know that the 1571 Disk Drive  has  the 
capability of reading and writing to both formats with the use of the  proper 
software.  We'll  get into this  more bellow.  The thing to remember here  is 
that  all Native Commodore operating systems (home computers) including  CP/M 
use the GCR format.

     Well  armed with this information what else do we need to know?  For one 
it  is important to know whether you are using a single or double sided  disk 
format.  For  another it is important to know which operating system (or disk 
drive)  your  disk was formatted on.  The types of disk formats  we  will  be 
discussing here are the following:

a.  C-64    Single Sided  1541 
b.  C-128   Single Sided  1571 (1541 compatible)
c.  C-128   Double Sided  1571 (not 1541 compatible)
d.  C-128   CP/M (GCR) 1571 Single Sided (1541 compatible))
e.  C-128   CP/M (GCR) 1571 Double Sided (not 1541 Compatible))
f.  C-128   CP/M (MFM) IBM (CP/M-86) Single Sided 1571 (not 1541 Compatible))
g.  C-128   CP/M (MFM) IBM (CP/M-86) Double Sided 1571 (not 1541 Compatible))
h.  MSDOS   IBM Double Sided (9 tracks) DOS Version 2.0 or higher.

     As you can see I have listed the Disk types in upward compatible  order. 
Commodore did develop a CP/M version (2.2) for the C-64 which required an add 
on  cartridge to implement and as such I've included it in our list  although 
we  will  be  discussing the 128 Version here which is CP/M + (Ver  3.0)  and 
takes advantage of the 128's Banked Memory (additional 64k as opposed to only  
64k for Ver 2.2).

    The  Stock C-128 CP/M Operating System which comes with the  computer  is  
capable of reading and writing formats d.  e.  f. & g. noted above. The stock 
system  is  also capable of reading  Kaypro And Epson Formats  as  well.  The 
System  will automatically identify the disk type in current use in the lower 
right  hand corner of your monitor.  Note when a disk format other than a 128 
Single  or Double Sided format is used the user must tell the system  whether 
or  not the non-128 formatted disk is a single or double sided disk.  This is 
done  by  pressing the left or right arrow keys on the top row  next  to  the 
function  keys.  Failing  to identify the correct format can cause disk  read  
and  write  errors  so be sure to properly set the  system  for  the  correct 
format.   

     There are Two Public Domain Programs available that will enhance the  C-
128  Systems  ability to read write and format other CP/M formats.  They  are 
Called NFORMAT.COM and UNIDRIVE.LBR.  NFORMAT will allow you to format all of 
the  formats  indicated above and Osborne DD formats as well.  Unidrive  will 
allow  you  to  read/write up to 10 formats out of a  menu  of  25  different 
formats  not  supported by the stock O/S.  Although there are more than  200+ 
CP/M formats these 25 will surely enhance your systems capabilities and cover 
a range of the more popular formats you will encounter. 
 
     More  than likely at some point you will want to transfer data you  have 
created on your C-64 or 128 in native mode.  The stock system can't do  this. 
But don't get discouraged.  A real Nifty Program to read and transfer/convert 
Data  from  your  Commodore  disk has been put in the Public  Domain  by  Rob 
Tiloston called RDCBM21.LBR.  It will allow you to transfer binary  (program) 
files or sequential files you have created in native mode to your Ram Disk or 
second Disk Drive while you are in CP/M operating mode. The program will also 
convert  PETASCII  to ASCII for you as well.  CP/M uses ASCII files and  your 
Commodore  text files will have to be converted for you to use them  in  CP/M 
mode.  The program is very helpful in this respect and eliminates your having 
to use other utility files for the conversion. The other nice feature of this 
program is that you can transfer CP/M program files you have down loaded with 
your Native terminal program to a Commodore formatted disk directly to a CP/M 
disk  or  your  RAM disk while in CP/M mode.  This is a much  eaiser  way  of 
accomplishing  transfers than some of the earlier transfer programs that came 
out in the beginning days of C-128 CP/M.  The program is menu driven and easy 
to use and I highly recommend it for anyone just beginning in CP/M mode.  

     While  we're on the topic of Commodore to CP/M transfers I'll shift back 
into  Native mode transfer programs for just a moment.  There are 2  programs 
that  are available for use in 128 Mode to facilitate Disk to Disk  transfers 
of  Data.  One  is  a DEMO program of a commercial program  called  Big  Blue 
Reader and it will allow you to view MSDOS Data files on your 128. The actual 
program will implement full file transfers and I believe the current  version 
also supports CP/M transfer as well. The suggested retail price is $29.95. 

     The other Program is called CROSSLINK2.LBR,  CrossLink is a fully imple-
mented menu Driven Disk to Disk (2nd Drive optional)  transfer  program  that 
will   make just about any kind of transfer/conversion you can think  of.  It 
will  handle CBM,  CP/M and IBM Disk formats and  do  ASCII  PETASCII conver-
sions  as well PRG and Screen file conversions too.  This means that it  will 
convert just about any Commodore text file format into a usable CP/M or MSDOS 
format  that you require.  You can also use it to convert different text file 
formats  used by the various Commodore word processing applications  programs 
too. It is an absolute MUST HAVE utility for any one using more than one type 
of word processor on their Commodore computer. 

     The  major draw back with using either of these two programs  though  is 
that  they  are limited in the size of the files that they  can  transfer  to 
about  200 disk blocks or 40k of memory.  This is because they store the data 
being transferred in a RAM buffer and Don't transfer the data directly.  This 
can  be overcome by splitting a larger file into smaller ones for text  files 
but you will not have this option in the case of a Program  ARC or LBR  files 
which can't be split. For larger files you are going to have to use the RDCBM
program  above or employ a direct conversion method of tranfering  your  data 
such  as  a Null Modem Cable (See my article C-128 Interface for more info on 
this method).

     Now back to CP/M mode,  to use an MSDOS formatted disk on your 128 there 
is  a  program called RDMS233C.LBR.  This program will allow you to  copy  an 
MSDOS  disk  file directly to your RAM disk or second  drive.  File  size  is 
limited only to the available disk space.  The only problem with this program 
however  is that it will only read an MSDOS disk not write to it.  To get the 
Data back to an MSDOS format you will have to copy it to a CP/M disk and  use 
the Crosslink program noted above.

     For  those of you who will be doing a lot of MSDOS / CP/M transfers  and
don't  want to go through the Gymnastics of multiple file conversions I would 
highly recommend an MSDOS Program called UNIFORM.  It is a commercial program 
which  retails for $59.95 available at most retail software outlets that will 
allow  you to read/write CP/M disk on the second floppy drive of  your  MSDOS 
machine.  It  supports over 200+ CP/M formats and you can take your work home 
and  bring it back the next day if you use one of the Alternate  MFM  formats 
supported on the Commodore 128 noted above.  It's well worth the price if you 
do  a  lot  of  work at home and don't want to spend the extra  time  at  the 
office. 

     Well  that's  about all for now if you have questions or need help  with 
any  of  these programs drop me a line and I'll be glad to  offer  what  ever 
assistance I can. 

Happy *Puting*    
 -=[CARL]=- 

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