Date   : Mon, 16 Jan 1984 14:08:00-PST (Monday)
From   : Tony Li <Tli@usc-eclb>
Subject: Function 37

    Date: Mon, 16 Jan 84 16:47:20 EST
    From: David Towson (CSD) <towson@amsaa>
    To:   Tli@usc-eclb
    cc:   David Towson (CSD) <towson@amsaa>, Info-Cpm@brl-vgr
    Re:   Function 37
    Return-path: <towson@amsaa>
    Received: from AMSAA by USC-ECLB; Mon 16 Jan 84 13:57:58-PST

    Tony - It is my understanding that CP/M-80 detects a disk change by
    noting that the directory information that has been read from the "first"
    disk no longer matches the information read from the "second"
    disk, and that
    when this happens we get the familiar (although usually unwelcome) message
    "BDOS ERROR R/O", and the system must be reset.  Is this not so ?

I think that that's exactly correct.  Just one question:  How often
does CP/M-80 read the directory?  I don't know.  As I said, I'm not an
expert on CP/M-80.

    Second question:  If a given drive does have the door switch, and I want
    to have my BIOS pass the information from this switch to CP/M, what
    should the BIOS put where ?

I don't know.  I haven't done it.

Cheers,
Tony ;-)