ERRORLEVEL using batch files

Does anyone know of a site that contains DOS commands that were specifically used in DOS batch files to return ERRORLEVEL values?

For instance, FINDRAMD.COM that is included on WIN95/98 CDs returns an ERRORLEVEL value corresponding to the drive letter of a RAM drive if one is present. FINDCD.COM is another one I've used in the past that returns an ERRORLEVEL value corresponding to the drive letter of a CDROM drive if one is present.

Specifically, I want to build a batch file that when run returns and reacts to various computer information such as:

- Machine Manufacturer/Model (IBM, Tandy, NEC. etc..)
- CPU installed (8088/86, NECV20/30, 286, 386, etc..)
- Total conventional RAM
- Total extended RAM (may be difficult/impossible without EMS/XMS driver installed)
- CMOS clock present/address
- Number/type of floppy drives
- Number/size of HDDs
- etc...

Even a program that returns these values into a file (text, CSV, etc..) would be useful as I could write a program that then reads that file and executes batch processes accordingly.

It's been many years since I've done any low-level coding in PASCAL or ASM on x86 hardware and I would rather not open that can of worms again if I can avoid it.

Any pointers on where to start would be most appreciated.