About OpenSol
OpenSol is an independently developed emulator created to preserve and explore the experience of the Processor Technology Sol-20 Terminal Computer.
- Introduced
- 1976
- Processor
- Intel 8080
- Display
- 64 characters × 16 lines
- Expansion
- Five S-100 slots
The Sol-20 in context
Processor Technology introduced the Sol family in 1976, near the beginning of the personal-computer era. Many contemporary microcomputers expected their owners to assemble a system around switches, circuit boards, and a separate terminal. The Sol-20 instead brought an Intel 8080 processor, full keyboard, video-display circuitry, cassette interface, and expansion capacity together in a distinctive enclosure with walnut side panels.
Its built-in character display and keyboard made the machine feel unusually direct and approachable for its time. The Sol-20 could be connected to a monitor and used as an interactive computer, while its five S-100 expansion slots allowed owners to add memory, storage, and other hardware. The Smithsonian describes it as a popular early personal computer whose case and integrated design influenced later machines.
Software on a character display
The Sol-20 displayed 64 characters on each of 16 lines. Programmers turned that modest text screen into editors, languages, utilities, and animated games. Instead of a modern pixel-based graphics system, software built motion and shapes from characters written directly into display memory.
TREK-80 and TARGET
OpenSol is compatible with lawfully obtained Sol software, including classic games such as TREK-80 and TARGET (also identified by the filename TARG). TREK-80 presented real-time space combat on the Sol display. TARGET used animated character graphics for a fast shooting game in which the player aimed and fired at moving ships.
OpenSol does not include these games, SOLOS, or other third-party ROMs and software. Users must provide their own lawfully obtained copies. Compatibility can depend on the particular software image and emulated configuration.
About the emulator
OpenSol was written by Jordan Ruderman for iPhone, iPad, and Mac. It emulates the Intel 8080 environment, Sol-style keyboard and video behavior, and a compatible command monitor using independently written code. The goal is to let modern users experience the character, constraints, and creativity of the Sol Terminal Computer nearly 50 years after its introduction.
Inspired by Lee Felsenstein's original design, OpenSol was made so others can experience a 50-year-old computer today on modern Apple devices.
OpenSol is not affiliated with or endorsed by Processor Technology Corporation or any successor rights holder.
Historical references
- Smithsonian National Museum of American History: Sol 20 Microcomputer
- Computer History Museum: SOL Terminal Computer
- Processor Technology Sol Systems Manual
- Processor Technology Gamepac 1 manual
- TREK-80 User's Manual
About Jordan Ruderman
Jordan Ruderman is a technology engineer and lifelong vintage-computer enthusiast. His career has included engineering and leadership work at Apple, Amazon Lab126, Fitbit, Cruise, and General Motors. OpenSol brings together his passion for preserving early personal computers and his experience building modern consumer and automotive technology. Find Jordan Ruderman on LinkedIn.