All my steps to be able to M-x compile 8051 projects from Emacs.

1. Make sure make is in the path.  (The following are for Win 7 without admin rights)
   1. Computer->Properties->Advanced system settings->Environment Variables
   2. User variables: New/Edit…
   3. Add C:\MinGW\msys\1.0\bin; (of course you need MingW installed)
2. If your Makefile is not in the same directory as your source. Check out the tips here.
3. Setup parsingof x51 output. Add to your .emacs:

   (require 'compile) (add-hook 'c-mode-hook (lambda () (add-to-list 'compilation-error-regexp-alist 'x51) (add-to-list 'compilation-error-regexp-alist-alist '(x51 "^... \\(\\w+\\) .*IN LINE \\([0-9]+\\) OF \\([^ :]+\\)" 3 2 nil 1)) )) (setq compilation-auto-jump-to-first-error t) 

4. Now you can M-x compile
5. and review your errors
   1. C-x ` (next error)
   2. M-g p (previous error)

Related reading:

• Compiling and Testing Programs
• Local Variables in Files