Historic Computer Re-creations
If the firmware is loaded on an Arduino Due and run without any front panel hardware connected, the emulator will automatically detect this and force RUN mode. This allows BASIC or other programs to run on a bare Due with nothing but a USB serial connection. With headless mode enabled, panel-related features (LEDs, switches, DEPOSIT/RESET actions) are simply ignored. Install ... Read More
Version 1.0.3 and later have a location to add an ESP-01s: This can be used to communicate with the Altair-Duino 680 via Telnet over a Wi-Fi connection. You can order this module from my website, or you can purchase one from many online sellers and program it yourself (using this code). You will need to connect to an available Wi-Fi ... Read More
The Altair 680 did not recognize the backspace key as we use it today. Instead, the user was expected to correct entry errors by using a rubout character. On the Altair 680 the rubout character is the underscore (“_”). Entering an underscore meant the previous character was ignored (although not removed from the screen). Remember, this computer was created back ... Read More
VTL-2: To load VTL-2 (Very Tiny Language), first make sure the VTL-2 ROM is installed (using Startup Options), then make sure your emulator is switched to RUN mode. At the monitor prompt, type “J FC00”. Once you press the last zero, VTL-2 will start and you will be greeted by the “OK” prompt. You can see a directory of VTL-2 ... Read More
You can change the startup options using the address toggles and holding RESET DOWN while starting the emulator. The first two bits (A0 and A1) represent the ROM image that is loaded. 0x00 = 680 Monitor ROM, 0x01 = VTL-2 ROM, 0x02 = FLEX ROM. The second two bits (A2 and A3) represent the port used for input and output. ... Read More
The Altair 680 front panel functions much like the original microcomputer, allowing you to directly interact with memory and control program execution. Address Switches (bottom 16 toggles): Set the memory address for Examine or Deposit operations. Data Switches (upper-right 8 toggles): Used to enter a byte of data to deposit into memory. DEPOSIT UP (momentary): Writes the value from the ... Read…
Operating Your Altair 680 Now that your Altair 680 emulator is fully assembled, this section will guide you through powering it on, connecting to a terminal, and loading BASIC just like the original 1976 MITS Altair 680. Powering On and Connecting The Altair 680 emulator is powered either through the rear-panel power jack using the included AC adapter, or directly ... Read More
While I was working on my Altair 680 emulator, something strange started happening. I’ve been selling an Altair 8800 emulator for about eight years now, and in all that time, no one has ever told me they owned an empty 8800 case. Not once. But almost immediately after releasing the 680 emulator, I started hearing from people saying things like: ... Read More
Some users running the original Altair 680 Editor/Assembler on the Altair-Duino 680 emulator may encounter the following behavior: Assembly of even very small programs that contain symbols (labels) fails with ERROR 017 Programs without symbols may assemble normally The error occurs immediately during Pass 1 This is not an emulator instruction-execution bug. It is a memory-configuration edge case…
The Altair-Duino 680 emulator does not run at full, cycle-accurate speed compared to an original 1977 MITS Altair 680 system. The original Altair 680 used a Motorola 6800 CPU clocked at approximately 500 kHz. In contrast, the current firmware executes 6800 instructions at an effective rate of about 275 kHz (roughly 55% of original speed). Why this happens The original ... Read More