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IBM 5170  -  Basics, for 5170 beginners

•	There were different models of the IBM 5170 (IBM AT). Do not assume that what applies to one model also applies to the others. This is mostly due to the different types of IBM 5170 motherboard, and the different motherboard BIOS'.
•	The floppy drive supplied by IBM is a 1.2M one.  Click here to read about a problem caused writing to 360K floppies in that drive.
•	If your IBM 5170 has the optional second floppy drive:    - Be aware that for the 5170, IBM marked 360K drives by placing an asterisk on the front of the drive.  (Photo)    - The 5170's power-on self test (POST) will not boot from the second floppy drive (B:).
•	There is no built-in method of performing SETUP (BIOS configuration) ("CMOS SETUP").  Methods for performing SETUP are at here.
•	The hard drive type number entered into SETUP (BIOS configuration) ("CMOS SETUP") is usually not used for hard drive controller cards that contain a BIOS expansion ROM (e.g. SCSI cards) (e.g. XT-IDE/XT-CF cards). Some Seagate authored information on the subject is at here.
•	The RAM test, and on-screen count, done by the motherboard's power-on self test (POST): 1. excludes the gap between conventional (base) memory and extended (expansion) memory; and 2. excludes any expanded memory. An example of the on-screen RAM count is shown at here.
•	The BASIC that is built into the motherboard, Cassette BASIC, cannot write/read BASIC programs to/from floppy disks (or hard disk drives).
•	The "Bytes free" figure that Cassette BASIC displays, is not the amount of fitted RAM.
•	Not all ISA expansion cards will work in an IBM 5170. - Ensure that any card you acquire is IBM 5170 compatible - Ensure that any card you acquire does not conflict with any existing card. - If you have the 8 MHz version of the 5170, note that some cards designed for the 6 MHz 5170 are not compatible with the 8 MHz 5170.  See here.
•	Aged tantalum capacitors are known to explode.  That has happened to me many times, in the vast majority of cases, when I have acquired something that has not been powered on in years.  If the motherboard, or expansion cards, are exposed to your face when you power them on, then consider wearing glasses of some sort.  More information at here.