(Semi-OT) CS refresher for a Unix sysadmin

Hello, long time lurker here...

I have been working as Unix sysadmin and consultant for ~10 years, and
in the process I have forgotten a bunch of stuff from my University
days.

I was planning on getting some books to study at home, the idea is not
to go too deep into any subject but to get some info that will help me
become a more well-rounded professional.

So, can anybody recommend some good refresher books on:

1) Math in general -- I planned to get Knuth's Concrete Mathematics and
see if I can handle it. Any other recommendations?

2) Computer architecture -- interrupts, DMA, all that stuff. Something
PC-oriented would be best.

3) Operating systems -- I guess I should get the Tanenbaum here, unless
somebody can recommenda a lighter, more Unix- and Windows-centric
alternative.

4) Networking (that would be the ISO stack and TCP/IP -- I guess a
refresher of X.25 and SNA is no longer needed)

That would be it for now. I guess things like algorithms, compilers,
DB's, computability theory, etc. will have to wait until I get the
basics back in place. Well I *might* go back and write a Yacc parser
just for kicks...

Any recommendations are greatly appreciated. Also, if this is not the
right newsgroup to post, please let me know of any alternative.

Many thanks in advance,

Unix Worker

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