ID READ Mode for ROM CHIP Function Identification
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2005-Feb-15
The ID read mode operation aims to allow the system to know what functions or features are actually available to it. The system detects chip identification (ID) patterns in a multi-chip configuration by a single control line. This technique is usable for identification of any chip functions or features, such as contents of program or type of character font. Fig. 1 shows an example of the ID read mode application for a circuit board in which several sets of character fonts are implemented by multiple ROM chips, ROM#1-ROM#N. Fig. 2 shows a ROM chip functional block diagram. The chip has inputs for ID READ (IDR) and CHIP SELECT (CHS). ID REPORT (ID REP) is an output terminal to propagate the IDR signal to another chip.