SIMH is the most comprehensive package for emulating ancient systems.

SIMH can emulate the following systems:

• Data General Nova, Eclipse
• Digital Equipment Corporation PDP-1, PDP-4, PDP-7, PDP-8, PDP-9, PDP-10, PDP-11, PDP-15, VAX
• GRI Corporation GRI-909, GRI-99
• IBM 1401, 1620, 1130,  7090/7094, System 3
• Interdata (Perkin-Elmer) 16b and 32b systems
• Hewlett-Packard 2114, 2115, 2116, 2100, 21MX, 1000
• Honeywell H316/H516
• MITS Altair 8800, with both 8080 and Z80
• Royal-Mcbee LGP-30, LGP-21
• Scientific Data Systems SDS 940

I do maintain binary builds, along with software on sourceforge here.