• Please review our updated Terms and Rules here

CCPM : interpreting date and file stamps


Mar 7, 2023
Grenoble, French Alps

The CCPM documentation describes specific directory entries for file date/time stamps.
For example page 2-24 here: https://bitsavers.org/pdf/digitalRe...ent_CPM_Programmers_Reference_Guide_Jan84.pdf

I Create/Access  I Update        I Password I Reserved  I
I Time and Date  I Time and Date I Mode     I           I
 0                4                8         9         10

The problem is that I don't find the details of the create/access and update fields (4 bytes).
Does anyone knows how to interpret them ?
Assuming it is the same as timestamps on CP/M-Plus (3.0) on 8-bit platforms, the first two bytes form a 16-bit integer containing the number of days since Jan 1 1980. The next two bytes are the BCD hour and minute respectively. I would think that CCPM provides you with BDOS calls for accessing the file timestamps, and perhaps for interpreting them. This should also be the same format as the system time, except the latter includes seconds.
Looking at the CCPM documentation I was refering too, the base date for CCPM appears to be January 1, 1978. The rest of the interpretation is certainly the right one.
The floppy disk image I'm looking at is actually CCPM-86. The manual of this version also mentions January 1, 1978.
Capture d'écran 2024-04-02 172537.png