Error Logging in a Data-Display Terminal
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
A microprocessor-controlled CRT data-display terminal has a non-volatile read-write memory (NVRAM) containing a log of two-character codes indicating various types of errors which have occurred in the hardware or microcode. When the terminal is in its power-up diagnostic mode (Fig. 1), detection of an error by diagnostic microcode causes the error code to replace the oldest entry in a stack of ten entries. Then a pointer is updated to point to the next oldest entry. In an off-line mode (Fig. 2) depression of a code-display keyboard key enters a null code into the stack, then displays the error codes in the stack entries on the CRT. The null entry provides a separator dividing error codes logged before the previous log display from those logged afterward.