User`s guide

Table 2-6. SFCB Subfields Format
Offset in Bytes I SFCB Subfield Contents
0 - 3 Create or Access Date and Time Stamp field
4 - 7 Update Date and Time Stamp field
8 Password mode field
9 Reserved
An SFCB subfield contains valid information only if its corresponding FCB in the
directory record is an extent zero FCB. This FCB is a file's first directory entry. For
password protected files, the SFCB subfield also contains the password mode of the
file. This field is zero for files that are not password protected. The BDOS Search and
Search Next functions can be used to access SFCBs directly. In addition, BDOS
Function 102 can return the file date and time stamps and password mode for a
specified file. Refer to Section 3, function 102, for a description of the format of a
date and time stamp field.
CP/M 3 supports three types of file stamping: create, access, and update. Create
stamps record when the file was created, access stamps record when the file was last
opened, and update stamps record the last time the file was modified. Create and
access stamps share the same field. As a result, file access stamps overwrite any create
stamps.
The CP/M 3 utility, INITDIR, initializes a directory for date and time stamping by
placing SFCBs in every fourth directory entry. Date and time stamping is not sup-
ported on disks that have not been initialized in this manner. For initialized disks the
disks' Directory Label determines the type of date and time stamping supported for
files on the drive. If a disk does not have a Directory Label, or if it is Read-Only, or
if the disk's Directory Label does not specify date and time stamping, then date and
time stamping for files is not performed. Note that the Directory Label is also time
stamped, but these stamps are not made in an SFCB. Time stamp fields in the last
eight bytes of the Directory Label record when it was created and last updated.
Access stamping for Directory Labels is not supported.
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2.3 BDOS File System CP/M 3 Programmer's Guide