Programming

comp.os.msdos.programmer FAQ
Freqently asked questions about programming for MS-DOS with tested answers.
http://www.jeffc.org/msdos/dos-faq.html

Mouse Programming in DOS
Information on using interrupt 33h for mouse programming. Includes free C source code.
http://www.geocities.com/rk_page/

Programming MS-DOS with Power
Information on most every aspect of DOS programming.
http://www.frontiernet.net/~fys/index.htm

Ralf Brown's Interrupt List (USA Midwest mirror)
A list of interrupts used on the Intel x86 architecture and their meaning with over 9000 linked pages and 350 indexes greatly ease the process of searching.
http://ctyme.com/rbrown.htm

386SWAT
A Protected Mode Debugger which provides debugging services to real mode, protected mode, virtual 8086 mode programs, DPMI and VCPI clients, and Win 3.1x and Win95/98 programs under any memory manager while occupying only a few kilobytes of low DOS memory.
http://www.sudleyplace.com/swat/

UPX
The Ultimate Packer for eXecutables is a portable, extendable, high-performance executable packer for several different executable formats. Freeware.
http://upx.sourceforge.net/

X2FTP Archive
General DOS programming material.
ftp://ftp.cdrom.com/pub/x2ftp/