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IBM 5170  -  Motherboard Revisions


There were 3 revisions 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)  • Stacked/piggybacked 128K-bit RAM chips of type 41128, rated at 150 ns (or faster)  • Each bank of RAM (this board has 2) = 16 data chips + 2 parity chips  • Can operate with only the first bank of RAM (bank 0 ) populated - see note 1
TYPE 2	6 MHz	13.8" x 9.4"		06/10/85	1 bank of 512 KB	• The main crystal is 12 MHz  • Uses 256K-bit RAM chips of type 41256, rated at 150 ns (or faster)  • The 1 bank of RAM = 16 data chips + 2 parity chips  • The form factor is not 'Baby AT'  (the IBM 5162, a later AT-class machine, introduced that) (more info here)
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)  • Subtle differences to a type 2 motherboard - see note 2  • Same RAM as the type 2 motherboard  • The form factor is not 'Baby AT'  (the IBM 5162, a later AT-class machine, introduced that) (more info here)

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
Note 2	Type 2 to type 3 differences noted:      • New BIOS      • Crystal Y2:  12 MHz to 16 MHz      • CPU:  80286-6 to 80286-8      • NPU:  80287-3 (5 MHz) to 80287-6 (6 MHz) (see here)      • Chip U82:  82284-6 to 82284-8      • Chip U83:  82288-6 to 82288-8