Date   : Mon, 30 Nov 1987 09:46:49 PST
From   : Bridger Mitchell <bridger%rcc@rand-unix.ARPA>
Subject: Z80DOS, PZDOS and datestamp formats

There is a resurgence of interest in CP/M 2.2-compatible bdos's;
at least two are under active development and not yet stable:  Z80DOS
and PZDOS.

Carson Wilson's doc file in the z80dos library tabulates the heritage
and major features of a number of variants; his z80dos is largely
derived from P2DOS.  Version 1.0 was released. 2.0 is being
beta-tested now and is available on some z-nodes.

Hal Bower and Cameron Cotrill have been perfecting PZDOS, also
derived from P2DOS; it is nearing release.

Automatic file time and datestamping is a feature many cp/m 2.2 users
already have by using DateStamper.  Z80DOS implements timestamps
in a manner similar to that used in cp/m 3 -- using 1 directory
entry every 4 for the stamps; however, its method conflicts
(destructively) with cp/m 3 file stamps.  PZDOS is aiming to give
the user the choice of either DateStamper or cp/m 3-type stamps.

The behind-the-scenes debate about timestamp formats is multifaceted.
(I'm the author of DateStamper; read with salt-shaker at hand).  Some
of the issues are:

The DateStamper format is the most portable -- DateStamper will run
with no bios or bdos modifications on virtually any cp/m
2.2-compatible system, including 8080 cpu's.  DateStamper includes
full create/modified/accessed times and dates.  But it requires the
most space -- 1.0 to 1.25 K.

The cp/m 3 and z80dos formats use up 1/4th of the directory entries,
require replacement of the bdos, but use no extra memory in a z80
system (8080 versions are not available).

A DateStamper disk can be transported to another cp/m 2.2
system and the datestamps will continue to be maintained on that
system if DateStamper is installed.  The other formats require a
compatible replacement bdos that supports their format.

It would be desirable to standardize on a single format for all of
cp/m 2.2; that would enable all of us to use all of the
timestamp-featured utilities that already exist (directory, filecopy,
disk catalog, unix-make, for DateStamper) and are being developed, and
to exchange fully-compatible disks.  But the jury is still out on
whether these dos's will evolve to that point...

--bridger mitchell