ANS:A - cache

MSD (Microsoft Diagnostics) was a software tool developed by Microsoft to assist in the diagnostics of 1990s-era computers. Users primarily deployed this tool to provide detailed technical information about the user's software and hardware and to print the gathered information, usually for use by support technicians in troubleshooting and resolving problems.
msd.exe Is A Process Used To Determine What Serial Ports Are Installed In Your Computer.

MSD provided technical information:

computer brand and processor information
memory (total, EMS, and XMS)
video (type such as VGA and manufacturer)
network
operating-system versions
type of mouse (if installed)
disk drives (and partitions), excluding CD-ROM drives etc.
LPT ports
COM ports
IRQ status
TSR programs
device drivers
other adapters.