MITS Altair AM Radio Music Jukebox
||by Bill Degnan
- 05/07/2018 23:13
Steve Dompier's May 1975 People's Computer Company newsletter article Music of a Sort (republished in Dr. Dobbs Feb 1976) describes how one would generate music with a MITS Altair by using the front panel to generate tones that could be received over an AM radio. The goal of this project is to experiment with ways to automate the use of this program by creating a "jukebox" interface that can be used from a period-appropriate terminal to play various musical selections.
After assembling the hardware I created the Jukebox program in phases. First I downloaded Dompier's program into RAM in location 0000 - 00xx via the serial port and used the DAJEN SCI monitor to run the music program from the monitor prompt. To execute, the command is: "G 0000". Next I converted the program into HEX so that I could copy to a 1702A ePROM chip, thus to avoid having to download the program through the serial port each time. I generated additional tunes by converting the notes from selected sheet music into octal format per Dompier's article. Both the DAJEN and 1702 ePROM burner use HEX format so I converted the notes and program into HEX format. Each line had to be checksum-ed manually.
Here is Dompier's music program and song data in HEX format, ready for a 1702A ePROM:
I repeated this process for a total of 6 1702A ePROM chips. Each line was manually checksum-ed.
> M 8000 80FF 0000
(move contents of 1702 prom containing music program to 0000)
> E 8
0008 00 D0 D0
(edit program to return to the monitor prompt, D0 after one play.)
> G 0000
*plays "fool on the hill" over AM Radio 1x and returns to SCI > prompt.
> M 8100 81B0 0020
(copy music data located in this block to RAM location 0020, over-writing what is currently there.)
> G 0
(run the program to play newly-copied tune.)
In all I created the following:
El Condor Pasa
In the Mood (among the first songs ever recorded played by a computer to generate signals received by AM radio )
Star Wars Theme
This Land is Your Land
You are My Sunshine
* * *
Hack A Day Writeup
||by Bill Degnan
- 08/03/2018 22:01
SDR ON THE ALTAIR 8800
by Tom Nardi
Thanks Tom, glad you liked the exhibit.