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From: bmaraldo@watdcsu.UUCP
Newsgroups: comp.sys.hp
Subject: Re: HP-28C Mem upgrade
Message-ID: <4080@watdcsu.waterloo.edu>
Date: Fri, 6-Nov-87 02:52:46 EST
Article-I.D.: watdcsu.4080
Posted: Fri Nov  6 02:52:46 1987
Date-Received: Sun, 8-Nov-87 07:24:54 EST
References: <44700004@uicsrd>
Reply-To: bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo)
Distribution: comp.sys.handhelds
Organization: Unit 36 Research
Lines: 24


  This describes the EduCalc memory upgrade for the 28C:

     Cut a hole in the back of the 28C:  Reason:  The 28C is heatstaked
     shut (which means they are completely sealed).  Then they connect a
     memory board from an HP71 memory upgrade module to the HP28C
     motherboard:  Reason:  The 28C uses a modified 71 processor, hence the
     buss is the same (10 pins!).  Then they insulate the board, stuff it
     into the body and seal the hole with a rubber plug which extends
     50/1000 inch from the back surface.  Price:  $270 for 32K, and 
     $180 for 4K.  One could simply buy a 71 32K module from Educalc ($150)
     and mount it theselves (being VERY careful when cutting the hole,
     especially if they are using a Dremel MotoTool).


				Brett L Maraldo

    
   p.s. anyone have any info on the pinout locations of the buss?
-- 
               --------     Unit 36 Research     ---------
	                "Alien Technology Today"
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	                    bmaraldo@watdcsu