Re: Question on Corvus controller card repair

[DawnWolf <dawnwolf@gmx.li>]

On Fri, 26 Aug 2005 22:49:26 -0700, Charlie Springer
<RAM@regnirps.com> wrote:

>> Ok, now I was searching Jameco for the parts needed to repair this card
>> and I did a search for one of the chips I need..  In this case:
>> 
>> hd74ls20p
>> 
>> The search results I received from Jameco are:
>> 
>>  -  IC,74LS20
>> 
>>   -    	  IC,SN74LS02N,DIP-14,
>> QUAD 2- INPUT NOR GATE
>> 
>>  -    	  IC,SN74LS20N,DIP-14,
>> DUAL 4-INPUT NAND GATE
>> 
>
>All three are good. You want a DIP (Dual Inline Package) and it is a 14 pin 
>DIP, and the 7402 does indeed have two NAND gates with 4 inputs each.

7420 is what you want, not 7402. See also
http://www.cs.uiowa.edu/~jones/logicsim/man/node5.html for naming
conventions. You're looking at a TTL chip, low-power schottky (the
LS), dual 4-input NAND gates (the 20). Not sure what the 'p' or 'n'
stand for, but DIP-14 is right. "HD" on your chip is the manufacturer,
in this case "Goldstar, Harris, HHSMI, Hitachi".

So, you want the SN74LS20N. "SN" means it's manufactured by "EAG,
Hitachi, Motorola, NS, Philips, Signetics, TI". 74LS20 is the chip you
need, again in a low-power schottky version - and the description says
it's DIP-14. DIP is Dual Inline Package - the package with the two
rows of pins on either side designed to go through a board and be
soldered on the reverse side of the board - or fit into a socket, of
course.