Electronic subtractor circuit for BCD code - uses subtractor to process BCD coding to control decimal display

摘要

A subtractor circuit is designed for operation with B.C. numbers to provide a compensation for display purposes. Each decade has five flip-flops (1-5) that are coupled to a display and transmission circuit. AND gates (30) are supplied with the stored value that lies in the range 10 to 19 and the decoded decimal values (40) are coupled to a display. Outputs generated over an OR (60) and NAND gate (50) are used (C1 to C4) as controls for the operation of the unit. When a display value, e.g. 8, is indicated and the stored value is 18, a number 4 is subtracted to set the memory value to 14 e.g. LHHHL.