Section 33F. If the system employed makes use of a computer, or similar counting unit for the tabulation of the vote cast either on paper ballots or punched cards, the city or town clerk shall designate, no later than one week prior to the date of the primary, preliminary election or election, a central tabulation center, or may designate all the polling places as tabulation centers, where such ballots or cards shall be counted. There shall be at least one computer or counting unit at each such tabulation center. If a central tabulation center is designated, it may be located in any municipality within the commonwealth; provided, however, that said tabulation center is no greater distance than fifty miles from the municipality conducting said primary, preliminary election, or election. Said clerk shall also require that a program for the counting of the votes, prepared by a suitably skilled technician, be in readiness for use in said computer or counting unit, no later than the fourth day prior to the primary, preliminary election or election. Said clerk shall cause to be prepared a set of ballots or punched cards, whichever is appropriate, so marked or perforated as to adequately test the programmed computer or counting unit, to demonstrate its rejection of cards or ballots which contain more votes for any office than the voter is entitled to, and to test any other contents of the program which in the opinion of the clerk may have a bearing upon the accuracy of the count to be made by such computer or counting unit.