chymes@zug.csmil.umich.edu (Charles Hymes) (03/11/91)
---------------------- The PD I/O expantion board I just built dosent work, and the current thing to try is to replace the chips. The board uses a R65C22p1 CMOS VIA a R65c52p1 CMOS DCIA and a MC4F139 IC. Ive gotton ahold of a number of 74LS139 chips, and I'm going to replace the MC74F139 with it. The difference being LS vs F. I think LS means low power Shottsky, but what does F mean, and can I interchange the chips? Does this make them incompatable? Thanks for the info, Charles
griffin@frith.uucp (Danny Griffin) (03/11/91)
chymes@zug.csmil.umich.edu (Charles Hymes) writes: >The PD I/O expantion board I just built dosent work, and the current >thing to try is to replace the chips. The board uses a R65C22p1 CMOS >VIA a R65c52p1 CMOS DCIA and a MC4F139 IC. >Ive gotton ahold of a number of 74LS139 chips, and I'm going to replace >the MC74F139 with it. The difference being LS vs F. I think LS means >low power Shottsky, but what does F mean, and can I interchange the >chips? Does this make them incompatable? F means Fast. Whether or not it makes a difference in this application I don't know, but I would suspect so or it wouldn't have been spec'ed. I also built the PD I/O and had some problems. If you are having problems with the serial port, (like with different parities not working) make sure you get the new newser.device. If you are having problems with the parallel ports, it is something you did. After building the board, nothing worked at first (at leat the way I wanted it to) :-) but now all the new ports work fine. -- Dan Griffin griffin@frith.egr.msu.edu
tomb@hplsla.HP.COM (Tom Bruhns) (03/13/91)
Ive gotton ahold of a number of 74LS139 chips, and I'm going to replace the MC74F139 with it. The difference being LS vs F. I think LS means low power Shottsky, but what does F mean, and can I interchange the chips? Does this make them incompatable? ---------------------- Not incompatible, per se, but you should know that the speeds are much different; the F series is FAST: Fairchild Advanced Schottky TTL or something like that. LS is low power Schottky, and about half as fast, depending on the particular type. (didn't bother looking up 139's for you.)
jcg852@jcsneuro.uucp (John C Gallant) (03/14/91)
tomb@hplsla.HP.COM (Tom Bruhns) writes: >Ive gotton ahold of a number of 74LS139 chips, and I'm going to replace >the MC74F139 with it. The difference being LS vs F. I think LS means >low power Shottsky, but what does F mean, and can I interchange the >chips? Does this make them incompatable? >---------------------- >Not incompatible, per se, but you should know that the speeds are much >different; the F series is FAST: Fairchild Advanced Schottky TTL or >something like that. LS is low power Schottky, and about half as fast, >depending on the particular type. (didn't bother looking up 139's for >you.) You can be sure that if an LS type chip would be guaranteed to work reliably it would have been used. FAST chips are more expensive and consume more power (I think) compared to LS chips, and they would only be used where an LS chip won't do the job. I wouldn't substitute. John Gallant Centre for Resource and Environmental Studies Australian National University email: jcg852@csc.anu.edu.au fax: +61 6 249 0757
rich@documail.UUCP (Rich McCallister) (03/20/91)
In article <1991Mar11.063722.16378@msuinfo.cl.msu.edu>, griffin@frith.uucp (Danny Griffin) writes: > I also built the PD I/O and had some problems. If you are having problems > with the serial port, (like with different parities not working) make sure > you get the new newser.device. How new is the new newser.device? I also built the PD I/O. I'd like to check to see if mine is out of date.