Altair8800_Mister
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README.md

Altair8800_Mister

alt text By Fred VanEijk and Cyril Venditti.

What is an Altair 8800

https://en.wikipedia.org/wiki/Altair_8800

How to control the MiSTer Altair8800

  • To move the cursor use the directional arrow keys (Left – Right – Up – Down).

  • Toggle switches

    • SENSE/DATA/ADDRESS
    • OFF/ON
    • STOP/RUN
      • 1 key - On - up
      • 2 or 0 key - Off - down
  • Momentary switches

    • SINGLE STEP
    • EXAMINE
    • DEPOSIT
    • RESET
      • 1 key - Up
      • 2 key - Down
  • Not implemented switches

    • CLR
    • PROTECT
    • AUX

Available samples

These samples are accessible through the MiSTer Core OSD (F12) in the "Select Program" section.

  • Empty

    256 bytes of zeroed memory at address 0x0000.
    
  • zeroToseven

    256 bytes of memory with 1st 8 bytes as 0 to 7.
    
  • KillBits

    Kill the Bit game by Dean McDaniel, May 15, 1975
    Object: Kill the rotating bit. If you miss the lit bit, another bit turns on leaving two bits to destroy. 
    Quickly toggle the switch, don't leave the switch in the up position. 
    Before starting, make sure all the switches are in the down position.
    
  • SIOEcho (See Serial port section)

    256 bytes to test serial port at port 00/01.
    Just echos the character typed on the terminal.
    
  • StatusLights

    Demonstrate status light combinations.
    Halts the cpu when done so requires a reset of the core.
    
  • Basic4k32 (see Serial port section)

    Basic interpreter in 4k ram at 0x0000 with a total of 8k of memory including the interpreter.
    Comumicates with serial port requires SENSE swithes to be set to 0xFD.
    this is the basic interpreter originally created by Bill Gates and Paul Allen.
    

    The Basic4k32 require the serial port to be setup and the sense switches to be set this way:

    • 15 to 10 ON
    • 9 OFF
    • 8 ON

Altair operation

http://altairclone.com/altair_experience.htm

OSD explanation

MiSTer Core OSD (F12) :

  • “Select Program”

    See Available samples section.
    
  • “Load Program”

    • Do this switch sequence:
      • Turn the ON/OFF switch to ON
      • Insure that the STOP/RUN switch is STOP
      • Load a program by using the "Select Program" option then press "Load Program". Once you press "Load Program" the Core will place that program in memory.
    • Finally do:
      • RESET with the RESET/CLR switch
      • Turn the STOP/RUN switch to RUN
  • “Enable TurnMon”

    Makes available the turn key monitor at address 0xFD00.
    See file "Altair8800_Mister/core/roms/altair/turnmon.txt".
    
  • “Reset”

    This will reset the core.
    

Serial port

  • To use the serial port you need to have an I/O Board v5.5 or do a hardware Wiring:
    • Any USB to 3.3V (NOT 5.5V) TTL Serial Cable Adapter should work.
    • TX SDA Arduino_IO14.
    • RX SCL Arduino_IO15.
    • Don't forget to wire the Ground.
  • Use Putty or TeraTerm for client and use the 19200 baud setting.

alt text

Credits

  • Inspiration for displaying the Altair8800 front panel:

    https://timetoexplore.net/blog/arty-fpga-vga-verilog-01
    
  • Altair8800 front panel image:

    http://www.vintage-computer.com/altair8800.shtml
    
  • Core:

    https://github.com/1801BM1/vm80a
    
    https://zeptobars.com/en/read/KR580VM80A-intel-i8080-verilog-reverse-engineering
    
    https://hackaday.com/2015/03/07/looking-inside-the-kr580vm80a-soviet-i8080-clone/
    
    https://jeelabs.org/2016/09/i-never-had-an-intel-8080/
    
    https://github.com/mmicko/s100fpga
    

Known issues

Depending on your monitor resolution the Altair8800 front panel might not be complete or centered.

Not implemented

The following switches/functions are not implemented:

  • CLR
  • PROTECT
  • AUX