From: Nicolas Welte (welte_at_chemie.uni-konstanz.de)
Date: 2002-06-27 12:58:00
Hi, 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 2114. The pinout is (just for the records): uPD445 +---\/---+ 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. Nicolas Message was sent through the cbm-hackers mailing list
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