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Flexible Character Generator Test Disclosure Number: IPCOM000059988D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08

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Olson, DR [+details]


Terminals or other devices which use character generators can change the character generators at any time without the need to change the microcode for testing the generators. The first step in this design is to have three locations in the generators assigned to diagnostics. For instance, these locations could be x'c8', x'c9', and x'ca'. Next, the characters which are in locations x'55', x'5a', and x'a5' are duplicated in the diagnostic locations. These locations are not randomly selected but are chosen because they allow the address lines to be fully tested, as can be seen by observing the addresses in their binary form: b'01010101', b'01011010', and b'10100101'. This is the only constraint that is put on the design of the character generators. The next step is the design of the test itself.