Computers

By Michael Podanoffsky; Addison-Wesley, 1994, ISBN 020162687X, has CD-ROM. Explores DOS structure, function from programmer view, overall architecture, command structure, code-level details of vital actions. [Amazon.com]

Fast industrial strength DOS compatible RTOS, supports huge disk drives, FAT32 volumes, Windows 95/98 long filenames, coded in Assembly, used mostly in embedded systems and similar uses. [Open Source, GPL]

Several Zip format files: readme, bootable MASM files: RxDOS sources, binaries. Another OS: RTX, fast, multithreaded for DOS in C.