Micro-cap is a pspice based graphical circuit simulator program, an expensive program. 40 years later, the company closes and the software is given away free. Few months later the website disappears.
The website is back!
Download this software here: http://www.spectrum-soft.com/download/download.shtm
Newsletters and some circuit code examples available here: http://www.spectrum-soft.com/news.shtm
Micro-Cap 12 Users Guide
Micro-Cap12 Reference Guide
Micro-Cap12 Brochure
Get it while it is still available. It is also available via archive.org.