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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