In the warm glow of the MicroBasement, SCELBAL (SCELbi BAsic Language) brings classic BASIC to the Scelbi-8B and Scelbi-8H microcomputers. With the Scelbi's 12K SRAM and 4K EPROM at the top (1702s containing the MEA Monitor/Editor/Assembler), SCELBAL loads from cassette tape into RAM and turns the 8008 machine into an interactive programming environment. This demo shows the real-world process used today: bypassing MEA by jumping directly to the cassette read routine, loading the tape, initializing variables, and running a simple program. In the MicroBasement, this tape-to-BASIC flow keeps the 1975 hobbyist thrill alive — one cassette hiss, one front-panel step at a time.
The Scelbi features 12K of static RAM for program and data storage, plus 4K of EPROM (1702s) at the top address space containing the resident MEA software. To load SCELBAL from cassette, we avoid starting MEA and jump straight to the cassette read routine at octal page 077.
Follow these exact front-panel steps to load SCELBAL (takes approximately 4.5 minutes once the tape starts):
| Step | Action | Switches / Notes |
|---|---|---|
| 1 | Start Tera Term | Configure: 110 baud, 7 data bits, no parity, 1 stop bit |
| 2 | Set address/data switches | 104 370 077 (octal) |
| 3 | Press INT | Enters interrupt mode |
| 4 | Press STEP | Advances to next byte |
| 5 | Set switches | 370 (octal) |
| 6 | Press STEP | Advances again |
| 7 | Set switches | 077 (octal) – cassette read routine page |
| 8 | Press STEP | Completes the jump setup |
| 9 | Press RUN | Starts execution at the cassette read routine |
| 10 | Start cassette tape playback | SCELBAL audio loads into RAM (~4.5 minutes) |
| 11 | After load completes | Set switches to 104 100 000 (octal) |
| 12 | Press RUN | Jumps to SCELBAL entry point |
| 13 | At READY prompt | Type SCR and press Enter to initialize variable space |
After SCR, enter this simple infinite loop:
100 PRINT "Hello World" 110 GOTO 100
Press Enter after each line. Then:
LIST and press Enter to display the program.RUN and press Enter to start it.The Scelbi will continuously print “Hello World” across Tera Term until you press the STOP switch or reset the machine. Classic 1975 BASIC magic.
SCELBAL on the Scelbi — loaded from cassette tape straight into 12K SRAM — was one of the earliest ways hobbyists could enjoy interactive BASIC programming on their own hardware. Bypassing the resident MEA EPROM and jumping to the read routine at octal page 077 made it possible to bring high-level language power to the 8008 without extra cost or complexity. In the MicroBasement, this demo keeps that 1975 excitement alive: tape hiss, front-panel steps, a READY prompt, and your own code running forever. It reminds us that the personal computing revolution started with simple hardware, clever software, and the patience to wait 4.5 minutes for something wonderful to appear on the screen.