freetradezone datasheets

From: Nicolas Welte (
Date: 2002-06-27 12:58:00


I just got my 14 day free trial access to freetradezone, now I can download
all the datasheets for obsolete components for free again. If someone has
some ideas what I should download, just let me know :-)

The only datasheet I needed was the NEC uPD445 1k x 4 static RAM chip, which
looks a lot like a 6550 (from the PET 2001) because it has the same oversized
DIL package, but with only 20 pins. I found a few of them in the trash, and
immediately thought I could use them as a better 6550 replacement than the

The pinout is (just for the records):

 1 -|a3   Vcc|- 20
 2 -|a2    a4|- 19
 3 -|a1   r/w|- 18
 4 -|a0  /ce1|- 17
 5 -|a5    od|- 16
 6 -|a6   ce2|- 15
 7 -|a7    a8|- 14
 8 -|gnd   a9|- 13
 9 -|io1  io4|- 12
10 -|io2  io3|- 11

od is output disable and must be 0 for normal operation. It is not an
additional chip select. Access times are 650ns for the standard device (L)
and 450ns for the device with L-1 suffix.


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