News and Discussion

• comp.os.cpm -- The main CP/M news group
• Vintage Computer Forums -- the Vintage Computer site's forums, with a "genre" dedicated to CP/M & MP/M and another to TRS, as well as other classic computers. Forums seem fairly active.
• comp.os.nowhere -- another newsgroup
• seattle-retrocomp -- Seattle Retro-Computing Society's news group
• CP-M.INFO -- "Discussion about the CP/M Operating System".

Historical Stuff

• Wikipedia -- Wikipedia's entry on CP/M
• A history of word processors -- includes WordStar.
• Wikipedia -- Wikipedia's entry on CP/M-86
• Herb Johnson's take on the history of CP/M; from his website
• Creative Computing Magazine -- from a contemporary perspective
• imsai.net -- Ex-IMSAI engineer Joseph "Joe" Killian's take.
• An anonymous history from 1998.
• Computer Storage History: From Magnetic Tape to the Cloud -- added by special request of Emilia. You go girl! STEM rocks!
• History of Office Technology -- A history of the evolution of office technology. Suggested by Christian. Hi, Christian!

Old Computer Sites

• Classic Computers -- Dave Dunsfield's site on "classic computers". Unfortunately, there doesn't seem to be any links from the mainpage into the site, making finding things there a bit difficult.
• Old Computers -- a goldmine of info on old computer and gaming systems.
• The Obsolete Computer Museum -- still onine, but not updated since 2002.
• Kee's Computer Home -- a collector of old computers.
• Kee's old computer links -- LOTS of 'em (and yes, I'm cheating).
• Seattle Retrocomputing Society -- Nice site design. Why didn't I think of that? :-)
• S100 Computers -- "A Web site for S100 Bus owners". The Altair and IMSAI, naturally, get lots of attention here. Has a forum and a nice software section, including lots of useful development tools.
• The CP/M 86 and 80 website, Bill Buckels' site, with sections on Aztec and Mix C, TurboDOS, lots of Apple CP/M stuff, and more.

Software and Documents

• MDFS.net -- Software and documentation for a wide variety of older systems. Includes sections on CPM and Z80, software and software development.
• Computer Programming History at CertStaff.com -- The linked page discusses the history of computer programming, but also has many links of interest to computer history.
• CoCoCoding. Dedicated to programming for the CoCo Computer. Also contains links to many CoCo and Tandy magazines from the '80s.
• Computer History: Storage, Software and Memory.

TRS-80 Sites

• CoCo/OS-9 Archive -- "an archive of material relating to the CoCo or OS-9", focusing on documentation (unfortunately, the link is way to slow to make mirroring practical). Get 80-Micro issues here.
• System-80 -- Terry Stewart's NZ-based dedicated to System-80, an Australian TRS-80 Model I clone. Documentation and software downloads.
• Nemesis -- Frank Durda IV's site with a bit of TRS-80-related material, including the LS-DOS 6.3.1 Restoration Project, The Assembly Language Development System and a bit more.
• Dave's Old Computers -- his page on TRS-80s.
• TRS80Stuff.net -- A nice-looking site that draws you in with its promise of lots of downloadable software then -- BAM! -- its PHP download script is broken and you can't actually get any of the stuff. Site hasn't been updated in three years. UPDATE: the old site has been removed, but the downloads (now working) are still available. The site is now mirrored by *HUMONGOUS* TRS-80.
• TRS80.org -- One of the largest -- and almost certainly the most active -- remaining TRS-80 sites, run by Matthew Reed. Interviews, software, book and magazine reviews, much more.
• Dr. Luis O. Tedeschi -- a personal webpage dedicated to the CP-300/500 Brazilian TRS-80 clones. Play Model III software in a java window.
• Miguel Dutra -- Miguel's homepage dedicate to the CP-500. Another promising site gone bust: Miguel's intriguing utilities for r/w-ing .DSK/.DMK disk images supports *every* O/S format. Except CP/M. UPDATE: (April 2013) Site is gone now, but *HUMONGOUS* TRS-80 has a mirror from 2011.
• The TOSEC Project is "dedicated to the cataloging and preservation of software, firmware and resources for microcomputers, minicomputers and video game consoles." The collections aren't available for download (apparently, they have to be purchased), but I managed to find a copy of the TRS-80 collection on the 'Net.
• Ira Goldklang -- Ira Goldklang's TRS-80 Revived Site. While the software and literature collections of old are gone, Ira's site still remains a goldmine of information no the TRS-80 line of microcomputers. Though Ira's focus was on non-CP/M TRS-80 operating systems, there is much of great use here even for the CP/M Model 1/3/4 user. Be sure to check out his links pages.

Miscellany

• Coding courses and games - Added for Ava. Good luck on your Girl Scout badge!
• Retrotechnology - Herb Johnson's site
• Caldera's FTP Site -- A mirror of Caldera Inc.'s FTP site wherein they made DR-DOS and CPM 2.2 available for download.
• Anonymous site -- An anonymous site somehow connected with the JOYCE users' group. Sections on CP/M, PCW, Amstrad, and one dedicated to the site owner's own JOYCE programming and dis/assemly projects.
• Storage and Memory -- A timeline of computer storage and memory, outlining the evolution and growth of computer storage since the 1920s. Added at the request Don Smith's technology and design seminar students.
• History of Computing -- A chronology of computer history, from 3000BC to the present. Thanks again to Don Smith's technology and design seminar students!
• A Beginner’s Guide to Coding and Programming. Link suggested by Kyle. Thanks, Kyle! Good find.