| 摘要 |
A PROM (10) has a pre-programmed portion (10a) comprising one or more sub-routines (1-3) of instructional information, a look-up table (4), and an unprogrammed portion (10b). If a sub-routine (2) is found to contain a programming error, i.e. a bug (6), the whole of that sub-routine is re-written as a new sub-routine (2A) in the unprogrammed portion of the PROM. The addresses of the original and new sub-routines are entered into the look-up table in correlated relationship. An instruction is provided at the start of the defective sub-routine (2) which causes the look-up table to be consulted before executing the rest of the instructions in that sub-routine. The new sub-routine is executed in place of the original sub-routine if the look-up table contains information correlating an original sub-routine and a new sub-routine. If the look-up table does not contain correlation information the original sub-routine is executed. <IMAGE> |
