Tpasm is a command line based cross assembler for a variety of common
microprocessors and controllers, currently supporting:

Rockwell 6502 (6502, 65c02)
Motorola 6805 (6805, 68705), 6809, 68hc11
Intel 8051 (8031, 8032, 8051, 8052, 80c390)
Atmel AVR (avt, attiny, at90, atmega series)
Core Technologies CTXP-1
Microchip PIC (12xxx, 14xxx, 16xxx, 17xxx series)
Sunplus SPCxxx series
Zilog Z80 (z80, z180)

Features are:

    * True multi-pass assembly (will take as many passes as needed)
    * Multiple segments
    * Sophisticated expressions
    * Macros, repeats, conditionals
    * Arbitrary length labels
    * Local labels
    * Supporting new processors is reasonably straightforward
    * Can switch between processors during assembly

WWW: http://www.sqrt.com/