> I > think this particular document is probably an image scan from an > old data sheet since the CD4048 is ancient. That appears to be correct. TI inherited the CD4xxx CMOS line from Harris, who probably inherited it from RCA (or was it from Intersil, who got it from RCA?).
Contrary to what others wrote here, it is configurable to implement OR, NOR, AND, or NAND functions across all eight inputs, as well as a few other combinations (OR/AND, AND/OR, etc.). > It appears that Pin > 9 changes the polarity of the output This is correct. > and 7 and 10 set whether the > chips ands or ors the inputs. Correct again. > Is the expansion pin bidirectional or just an input? It is an input only. > My > chip only started working correctly after I connected that pin to > ground. I am not sure if it normally connects to the expansion > pin of a neighboring CD4048 or should be fed from the J output > which is Pin 1 of the neighboring CD4048. It should be driven from the J output of the first CD4048. The first CD4048, or any whose EXP pin is not being used, should have its EXP input tied low. (Although later, the data sheet implies that it should be tied high for certain functions??) > The only other thing I haven't figured out yet is whether > all four possible states of Pins 7 and 10 are used. They are, but the other combinations might be less useful to you. The Function Truth Table is: Ka Kb Kc -------------- 0 0 0 NOR 0 0 1 OR 0 1 0 OR/AND 0 1 1 OR/NAND 1 0 0 AND 1 0 1 NAND 1 1 0 AND/NOR 1 1 1 AND/OR The combination function OR/NAND, for example, does an OR across inputs A, B, C, and D; and and OR across inputs E, F, G, and H; and then a NAND across the outputs of the two OR's. Andy -- Author: Ingraham, Andrew INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
