Of course you are correct for prior to v5.5 dos.
With the advent of ATAPI there are no specific drivers for cdroms as they are done over the IDE interface to the ATAPI specification (unless they are SCSI or specialised).
Therefore MSCDEX was the only TSR required to be loaded in a DOS environment and no .sys driver was required.
Jofm5 -
I see where you are coming from, however:
The device driver had to be loaded in Config.sys in every version of MS-DOS up to 6.22.
There was no MS-DOS 5.5 (it went 5.0 to 6.0, then 6.20, then 6.22).
MS DOS 7 was the 16-bit "underpinning" of Windows 95A. DOS 7.10 (that underpinned Win 95 B and above) was the first version of "DOS" to do away with the requirement to install the device driver.
And you are right about himem, but I only put in the lines specific to the CD drive in the example!
SD