HS      TECHNICAL BULLETIN                         COPYRIGHT 1984  TB 200:1


XFS

                              TB 200:1
                             PAGE {P} OF 1

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DATE:             March 4, 1985   

REVISION DATE:    March 4, 1985 

BULLETIN NO.:     200:1 

PRODUCT:          26-3860  (Model 200)       

SUBASSEMBLY:      Main Logic PCB                           
                                                           
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PURPOSE:  To describe memory upgrade and checkout procedure.                              
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_+DISCUSSION+_:                                                  

The Model 200 has the capacity to handle up to 72k of RAM.  However, to
see the additional memory after the upgrade is installed, one must use
the RAM bank select function.
                                                                    

_+PROCEDURE+_:                                                             
Note:  To perform any memory upgrade, first turn the memory power switch
(located on the back of the Model 200) to the "off" position.  Do not turn
the memory power or the main power switches back on until the upgrade is
completed.

To bring the Model 200 up to 48k, install the RAM option kit (cat. no.
26-3866) in the first option RAM position.  To bring the Model 200 up to
72k, install two RAM upgrade kits, one each in RAM option positions one
and two.

To check the system out, turn the memory power and main power switches 
on.  On the LCD, a menu screen should be displayed.  In the upper right
hand corner of the display, next to the Microsoft logo, should be a pound
sign followed by a single digit number (for example, "#1").  The first
bank of 24k is denoted as #1, the second bank as #2, and the third bank
as #3.  To determine whether the Model 200 sees the additional memory, use
the "F1" or "TAB" key to switch banks.  As you press either key, the   memory bank number should increment by one until the third bank is reached, whereupon it will return to the first memory bank.  For the     amount of free RAM in each bank upon startu
, you should see the message
"19590 Bytes Free" displayed in the lower right hand corner of the screen.
For a thorough memory test, the diagnostics should be run on each bank
of RAM.