Circuit arrangement for a programmable electronic control device

摘要

In the case of a programmable electronic control device having one or more memories which contain a standard program which can be extended by a supplementary program contained in an additional memory, which supplementary program can be called up, for example as subroutine, by the standard program, it is ensured that when the additional memory is not present, the program run is continued without further storage space being needed for additional operations when the additional memory is not present. By means of high-resistance resistors, a particular bit pattern is generated at the data multiplexer connecting the control device to the memories, which bit pattern is produced by connecting the resistors to the operating voltage or operating earth. Because of the high-resistance resistors, this bit pattern is suppressed by information which is read out of the memories. If then the non-existent additional memory is selected by the control device, no information passes from it to the data multiplexer as a result of which the bit pattern present there becomes effective. This bit pattern is used for causing the control device to continue the program at a particular point.