Tpasm is a command line based cross assembler for a vast 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)

Its features include:

  * 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