(scroll down for instructions)
Cassette:  Cassette: 

Virtual Sphere 1 Computer

Now you, too, can have the questionably-entertaining experience of using the obscure Sphere 1 from 1975! This emulator reflects a standard system, with 20k of RAM and a cassette input. The ROM firmware has been modified (as most real users did at the time) to make loading from tape easier.

When the computer resets to the blank screen and blinking cursor, it is in "executive" mode, ready to accept commands. You can use the shortcut buttons at the top of the screen to quickly access a Snake game or a version of BASIC!

But if you want the full 1970s experience, here's how to load a tape and run the program:

  1. Drop down the cassette menu and pick a tape program.
  2. Enter L ("load"), followed by the notation given in the cassette dropdown for this tape. For example, to load the Snake game, L SN/0400. This code tells the computer what the file name of the program is and what memory address to load it into.
  3. Press the Escape key (not "Enter"!) to submit the load command.
  4. You should see some numbers and letters appear on the screen indicating the tape has loaded.
  5. Enter the debugger mode by pressing Control-D. You should see a > prompt indicating the debugger mode.
  6. Now "open" the memory address where the program was loaded. First type Control-O ("open"). Then enter the four-hex-digit address, which is the same as the four hex digits in the load command above. For Snake, this is 0400.
  7. Press Escape again (not Enter) to submit the command. You should see the address you entered appear along with the current value of the byte at that address. Now you are ready to begin the program.
  8. Press Control-G ("go"). The program will begin running. Some programs (Snake, Shooting Stars) will enter into an interactive mode. Some (Life) may not give you any hints (To seed the Life game after loading, try typing a bunch of keys and then pressing Escape.)

And that's "all" you need to do to run a tape program (oof)! You can interact with the debugger more extensively, and the executive mode also has a full-screen editor module. If you want to learn more about using Sphere's built-in Program Development System (PDS), click the "User Manual" button at the top for the immersive 1970s experience. Enjoy!

Note: this emulator version does not currently have the "mini-assembler" in firmware, since the tape routines have superceded it. Also note that you cannot "write out" to tape currently. If you can figure out the rules to Shooting Stars, please let me know.

This virtual Sphere was developed by Ben Zotto, and the emulator software, images and text is copyright 2022. This is part of a larger research project on Sphere.