I will be listing a large collection of IBM manuals, brochures and other ephemera dating from the late 40's to the 80's. 
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Small spiral bound reference book (5.25" x 8.75") for Guardian 90 Operating System Programming from Tandem Computers. This is the 2nd edition, 1989, for Operating System Guardian 90 C20.

The book is divided up into 9 sections: 

1. Quick Reference
2. Procedure Calls Summary
3. Section Title
4. Traps
5. Interprocess Messages
6. Program-Level Error Codes
7. Reference Tables
8.Instruction Set
9. ASCII Character Set
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See images. Definitely used. Great reference copy. Dings, wear & writing on covers. Writing on some pages. 
Pages are numbered by sections, so unsure of total number of pages- about 1/2" thick.
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Ask any questions before bidding/buying. 
Thanks for looking!

Box GB3