[comp.sys.dec.micro] Memory Upgrade Query

sherwin@video.dec.com (JIM SHERWIN) (01/12/90)

	Let me begin by apologizing that this query is originating from
	w/in DEC.  It's regretful how quickly we've forgotten this
	dandy little PC.  Enough said, on to my query.

	I have 2 PC100B (aka 100+) memory extension boards.  I am
	wondering if I can combine the chips from them onto a single
	board.  Doing so would entail using 256k and 64k chips on a
	single board.  Here are the details:

	Board #1 contains 9 chips with DEC part # 21-21415-02.  Our BOM
		 file describes this part # as:

		 NMOS DRAM 150NS 256KX1 PAGE MODE 16P DIP

		 The dip switches are set as follows

		 	Switch	1  2  3  4

		     ON		x  x  x  x
		    OFF

	Board #2 contains 18 chips with DEC part # 21-20549-02.  Our BOM
		 file describes this part # as:

		 NMOS DRAM 150NS 64KX1 PAGE MODE 16P DIP

		 The dip switches are set as follows

		 	Switch	1  2  3  4

		     ON		         x
		    OFF		x  x  x

	

	If combining them is possible, would anyone care to suggest what
	the proper dip switch setting would be and, assuming the base
	system has 128k, what the resultant memory would be?

	Thanks,

	Jim