ENGINEERING CHANGE NOTICE

ECN Number:__________2________________________

Product:_________HDCA Disk controller________

Part Number(s):_____500-HDCA_________________

Current Board Revision Number:______all______

New Board Revision Number:___no change_______


Purposĺ  oć Change:_This change is to remove a possible race__

condition on the HDCA board when used in M26 systems with bus  

clocks in excess of 2 Mhz.____________________________________

Modifications (attach additional sheets if needed):Replace IC_

at location 13B (74LS163) with a NATIONAL SEMICONDUCTOR 74LS163.

This fix is a TEMPORARY FIX ONLY and does not totally eliminate 

eliminate the problem.  If NATIONAL parts are not available, use

Fairchild 74F163 parts.  A future ECN will supply a more complete

solution to the problem___________________________________________

APPROVED:      Engineering:______________________Date__/__/__

               Production:_______________________Date__/__/__

               Quality Assurance_________________Date__/__/__

               Customer Service__________________Date__/__/__

               Purchasing________________________Date__/__/__

               Marketing_________________________Date__/__/__

EFFECTIVITY:   [X]  Immediate - notify current production

               [ ]  Notify users and update stock

               [ ]  Phase in as stock is depleted


Submitted by:_Bob Groppo__________________________on __/__/__
 
Page_1_of_1_                                 Schematics?_yes___


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Form ECN Rev-2 9/83