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IBM 5170  -  Motherboard Versions


According to IBM user documentation, there are 3 versions of the motherboard.
IBM differentiated them by assigning a type number to them: type 1, type 2, type 3  (See here.)

	Speed	Form factor	Photo	BIOS supplied	Motherboard RAM	Comments
TYPE 1	6 MHz	13.8" x 12"	Photo	01/10/84	2 banks of 256 KB	• The main crystal is 12 MHz  (photo)  • RAM: Stacked/piggybacked 128K-bit RAM chips of type 41128, rated at 150 ns (or faster)  • RAM: RAM bank layout shown at here  • RAM: Can operate with only the first bank of RAM (bank 0 ) populated - see note 1  • ROM: See here
TYPE 2	6 MHz	13.8" x 9.4"		06/10/85	1 bank of 512 KB	• The main crystal is 12 MHz  • RAM: Uses 256K-bit RAM chips of type 41256, rated at 150 ns (or faster)  • RAM: RAM bank layout shown at here  • ROM: See here  • See here for comment on the 'Baby AT' form factor
TYPE 3	8 MHz	13.8" x 9.4"	Photo	11/15/85	1 bank of 512 KB	• The main crystal is 16 MHz  (photo)  • RAM: Same RAM bank and chips as the type 2 motherboard  • ROM: See here  • See here for comment on the 'Baby AT' form factor

Note 1

On the type 1 motherboard, swapping (either way) between single-bank operation and dual-bank operation requires the follow-up action of:      • BIOS reconfiguration via SETUP (so the BIOS knows what to expect at power on)      • Possible change of jumper J18