C-128 ROM Replacement
---------------------
 
Commodore recently released new ROM chips for both the 1571 disk drive and 
C-128 PC which corrected major and minor bugs found in the equipment.  If 
you are considering doing-it-yourself, information on where to purchase the 
chips and the pricing can be found in the *FlagShip* Commodore Bulletin 
Board.  Kevin Stevens has provided the instructions for installing the 1571 
Replacement ROM, and it can be found here in this same library.
 
What follows is a step-by-step instruction for replacing the three C-128 PC 
ROMs.  [*] NOTE: [*] This procedure will void your warranty, so if you feel 
uncomfortable then it may be best to let your local Commodore Service 
Center do the upgrade for you.
 
Before you start, consider whether you will want to also upgrade your VDC 
RAM.  It provides some superb capabilities, especially when used with the 
soon-to-be-released BASIC-8 system by Wallace/Darus.  Information on 
upgrading the VDC can be found in the October '86 issue of Twin Cities 128. 
(Send mail to SPARROW.J on GEnie for info on acquiring back issues)
 
 
EQUIPMENT NEEDED:
 Small Phillips Screwdriver
 Soldering Iron
 Small Vacuum Cleaner (optional)
 Needle-Nosed Pliers
 New ROM Chips (318018-04, 318019-04, 318020-05)
 
 
1) Remove all power and peripheral cords from all ports on the C-128.  
Place the computer upside-down on a soft surface and remove the six (6) 
screws from the cabinet bottom.  Ensure that static electricity is not a 
problem before continuing.
 
2) Hold the case together and turn it rightside-up.  Lift up the left side 
of the cabinet top and disconnect the Power Indicator Connector.  Note how 
you take it out so that you will replace it correctly later on.
 
3) Disconnect the Keyboard Connector and remove the screw in the lower 
right corner of the main board to free the Keyboard Grounding Strap.  (Note 
how you remove these as well.)  Lift the cabinet top and keyboard off of 
the cabinet bottom.
 
4) Remove the six (6) screws holding the main board to the shield assembly 
and carefully straighten the tabs which clip the board to the shield.  
Unsolder the top shield from the right side of the main board, and remove 
the final screw located just in front of the RF modulator (top of shield 
assembly near the center).  Lift of the top shield.
 
5) The following three chips reside on the left center of the board.  
Locate them now:
     U33  (318018-02)
     U34  (318019-02)
     U35  (318020-03)
 
6) The numbers on the NEW ROMs match up, except for the last number, so 
simply (and carefully) rock each old chip out of its socket and replace it 
with the new one.  Check your work now.  The following chips should be in 
the appropriate sockets:
     U33  (318018-04)
     U34  (318019-04)
     U35  (318020-05)
 
7) Before replacing the shield and cover, you may want to clean your board
thoroughly (mine was full of all sorts of micro-organisms).
 
8) Place the top shield back over the board and replace the screws.  With 
the pliers, place the tabs back over the board.  Re-solder the top shield 
to the main board on the right side.
 
9) Replace the Keyboard Connector, Power Indicator Connector, and the 
ground strap.  
 
10) Place the cabinet top on the cabinet bottom, turn it upside-down, and 
replace the six screws.
 
 --Happy Computing!
 
Mike Mantino
(GEnie Address: MICHAEL.M)