FLCHK.200 is in a form of hexadecimal file, and needs conversion to a CO file 
before it can be run.  Use HXFER.200 for this.

To check a file, enter its full name, including the extension(.DO, .BA, or .CO)

You can also check a range of memory space by entering the beginning and end  
of memory area, in decimal.
For example, entering:
60000,60099
at the 'File to check?' prompt will perform a checksum on 100 bytes of memory, 
beginning at address 60000.

The size of the file and checksum will both be displayed on the screen, and 
recorded in a file named CHKSUM.DO.

Checksums on DO files can be used to check files uploaded/downloaded in this 
sig.  Graphics characters and line length can also be checked.  A high beep and
a low beep will be heard for each graphics character and line with length over 
132 characters, respectively.