Basic OPEN ACCESS and File SHARE Unsupported in MS-DOS 1.x/2.x (79032)

SUMMARY

In Microsoft Basic and QuickBasic, you cannot perform file sharing with the ACCESS keyword of the OPEN statement under versions of MS-DOS earlier than 3.0. The result is an error 73, "Advanced Feature Unavailable."

This information applies to Microsoft GW-Basic versions 3.2, 3.22, and 3.23; Microsoft QuickBasic versions 3.0, 4.0, 4.0b, and 4.5; Microsoft Basic Compiler versions 6.0 and 6.0b; and Microsoft Basic Professional Development System (PDS) versions 7.0 and 7.1 for MS-DOS.

MORE INFORMATION

The following is a typical OPEN statement and its features (found in the language reference manual for each version of Basic):

  OPEN file [FOR mode] [ACCESS access] [lock] AS [#]filenumber [LEN=reclen]

In versions of MS-DOS earlier than 3.0, the ACCESS feature is not available because the MS-DOS interrupt 21 hex with function 3D hex (Open File) does not support file sharing under versions of MS-DOS earlier than 3.0. This is a limitation of the MS-DOS versions 1.x and 2.x.

If you use the ACCESS keyword in a Basic OPEN statement under MS-DOS version 3.0 or later, you must run the SHARE.EXE program (or the network startup must run it) before you can perform any file locking operation.

Under MS-DOS version 4.01, SHARE.EXE will be loaded automatically if there are hard drive partitions greater than 32K.

Note that Microsoft designed Basic PDS 7.0 and 7.1 for MS-DOS version 3.0 or later, as stated on the product box.