See how a computer executes your code while learning about the internal workings of modern computers.

Students or software programmers who want to learn how computers work will love this app. 
CPU8 simulates the SAP-1 (Simple As Possible) 8-bit bread board computer that was famously the star of a series of videos by Ben Eater.
Using it, you can control a fully realized computer that utilizes microcode to illustrate the operation of individual computer instructions and their interrelationships with general purpose registers, program counters, memory registers, instruction registers, bus and memory through "control words".
In addition, CPU8 contains an assembler that allows you to write programs and convert them into the machine language of the included simulated computer. A full programming manual is included.
Write, assemble and run programs using this 8-bit computer to see how the process works from start to finish.

- Assembler for the 8-bit computer (with manual)
- the 8-bit computer simulator
- 16 instructions - 3 pseudo instructions - 16 address spaces
- control the speed of the simulated computer clock
- single step through programs or run to the end
- 7 sample assembler programs to get started
- links to all the Ben Eater design and teaching videos
- A short history of computing through the ages (25 chapters)

Suitable for classroom study, independent study or just for the sheer enjoyment of playing with a computer that you can watch and learn from. No individual information is accessed.

Oh, did we mention it has wonderful flashing lights!

What’s New

Version 1.10.1

Additional History sections:
Section: Security, Encryption, Ciphers, Codes and Certificates
Section: Robots, Androids And Other Automatons
Section: Artificial Intelligence And Machine Learning

Enhanced support for M1 equipped Macs with larger screens.

Bug fixes and readability improvements

Commit: V 1.10.1 Build 347 -- Fixed readability problem with table in AI section and added the missing Security section

Commit: V 1.5.1 Build 416 -- Fixed readability problem with table in AL section

Ratings and Reviews

4.4 out of 5
7 Ratings

7 Ratings

LoveOfCountry ,

Nice tool to go along with the build

Only problem I’m having is there is no sound with your hint videos. The Ben Eater YouTube videos are fine. Tried on two different phones. iPhone X and Xs MAX. Thanks for putting this App out.

Developer Response ,

The hint videos were not recorded with sound. They are in keeping with the idea of hints.

There is a bit more detail at:

BasenjiBuddy ,

I really want to like this app…

This application is impressive, and the developer shows a great deal of passion in the implementation. However, if you are visually-impaired it is completely in accessible. Starting from the main screen onward, there are several obstacles to using it if you are low - vision or blind.

I attempted to navigate the developers website, but again the color scheme was too difficult to make that a possibility.

It is my sincere hope that these minor design issues can be corrected, because I see this as a very useful learning tool.

Developer Response ,

As it turns out, the developer is visually impaired. He does the best he can. Sorry the experience is so bad for you.

You can also adjust via “Accessibility” in “Settings”. The app will adjust to many accessibility settings to help those visually impaired.

App Privacy

The developer, Cordova Bay Entertainment Group, Inc, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Collected

The developer does not collect any data from this app.

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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