Search Posts:

MITS Altair AM Radio Music Jukebox

SHARE

Return to Threads

  MITS Altair AM Radio Music Jukebox by Bill Degnan - 05/07/2018 23:13
MITS Altair8800b AM Radio Jukebox Project
MITS Altair "Jukebox" system with GE Radio on top. Click image for larger view.


MITS Altair8800b AM Radio Jukebox Project
MITS Altair "Jukebox" system exhibit at the 2018 Vintage Computer Festival. Click image for larger view.


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.

Here is a photo of the front panel card, expertly repaired by Jon Chapman of Glitchworks, making this exhibit possible. Click image for larger view.


The DAJEN System Central Interface "SCI" controller. The DAJEN SCI is an all-purpose interface card compatible with most S-100 systems. The monitor commands are HEX based. I selected the DAJEN for the Altair Jukebox because its monitor program has a built-in RAM block move utility and because it's a change of pace from the other ROM monitors I have. I have also experimented with the MITS TURNMON and Vector Graphics ETKM ROM monitor programs. They all work about the same. The key role of the DAJEN is to move the music program and data stored in ROM at location 8000 to volatile RAM at 0000 for execution. Click image for larger view.


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:

:10000000211C007EFEFFCA0000163005C21000460B
:100010000DC20B0015C20B002CC303001C1C1C22BC
:1000200022222B2B2B393939332D2B33332B3939D2
:10003000393939392626261C1C1C2222222B2B2B2F
:10004000332D2B2626222626262626222022261C53
:100050001C22262B2B2B2B2622222B33332B3339FE
:10006000393939392B2B222626392B2B22262220CF
:100070001C222B2626392B2B2B2B020202020202DA
:10008000454555403933333339332D2B2B2D3933F7
:10009000262626393326262B2226263339332B2BA8
:1000A000332B39333339332626262B222B26262B86
:1000B0002D2B3936403939403936363940404039B0
:1000C00036303036393636302B2626262624262B57
:0B00D0002B2B2B2B020202020202FF6E
:0000000000

I repeated this process for a total of 6 1702A ePROM chips. Each line was manually checksum-ed.

Processor Technologies PTCO 2KR0 1702A S-100 ePROM card.
Pictured is the Processor Technologies PTCO 2KR0 1702A S-100 ePROM card. I used an ePROM "burner" to copy Steve Dompier's original music program and music data, plus tunes I converted from sheet music into HEX format. Each 1702A ePROM can hold up to a quarter of a Kilobyte (256 x 8 bits). The card is configured to store ROMs at 8000. Click image for larger view.


Godbout EconoRAM IV S-100
Pictured is a 16K Godbout EconoRAM IV S-100 RAM card. The RAM card is addressed 0000 - 3FFF but only the 0000 page is necessary. This card was selected because it was less "noisy" electrically than the earlier 8K EconoRAM II I had been using. Click image for larger view.


This is a photo of a California Computer Systems terminator card, used to help reduce S-100 bus "noise". Without it, the DAJEN has had trouble initiating the full ROM monitor. Click image for larger view.


Rear View, MITS Altair 8800B with Lear Seigler ADM 3a Terminal
Here are the connections on the back of the Altair and into the ADM 3a terminal. Note that there is a NULL Modem adapter on the Altair. Click image for larger view.


MITS Altair 8800B Jukebox cover removed to show controller cards.
Photo of the Jukebox with the Altair 8800b cover removed. Click image for larger view.


circa 1976 GE AM/FM Radio
The circa 1976 GE AM/FM Radio is perfect for the job. While the music program is running, AM-band radio signals are generated, producing music that can be received by a radio such as this. One can tune in the signal to reduce hiss and feedback. Click image for larger view.


This image shows the commands necessary to initiate the system. M is the "move" command and E is the "edit" command. G is for "Go". After the intial set up is complete each song can be loaded and played one time, returning to the DAJEN prompt ready for the next song. Ignore the ERROR messages, they are generated when one hits ENTER to escape the edit session. I am looking for a more elegant way to exit, but it's not really an error when you do. Click image for larger view.


> 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
(run program)

*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

* * *

Any requests?
More Photos

Pictured here is an RS232 breakout box used to turn off the RTS / CTS signals from the terminal. The DAJEN developed an issue that Corey Cohen identified as being a "stuck high" clear to send (CTS) signal. This problem caused the terminal to be unable to transmit back to the computer. Other than that exhibiting the Jukebox at the Vintage Computer Festival East 2018 went great. Click image for larger view.


Reply
  Hack A Day Writeup by Bill Degnan - 08/03/2018 22:01
SDR ON THE ALTAIR 8800
by Tom Nardi
https://hackaday.com/201...sdr-on-the-altair-8800/

Thanks Tom, glad you liked the exhibit.

Reply
  Altair Jukebox Video by Bill Degnan - 08/27/2018 08:11
Video:
https://www.youtube.com/watch?v=tSO2ofz4gD4

Reply

Resources:


Buy a Commodore Computer Poster

Popular Topics and FAQs


  • Commodore B Series Tips and Tricks
  • Aerocomp TRS 80 M 1 Expansion Unit DDC
  • Items Wanted
  • Lobo Max 80
  • Zenith Z-19-CN
  • Prototype PET 2001 photo
  • Using Toggle Switches to Analyze Memory
  • Commodore Disk Archive Project
  • PET 2001 Prototype at Gametronics 1977
  • Jim Butterfield Photo
  • IMSAI 8080 With Processor Tech. Cutter
  • Secrecy is the keystone of all tyranny
  • Cromemco System Three
  • Northstar Horizon - Boot Problem
  • Computer History and Restoration Links
  • Commodore BX-256-80 - 8088 Co-processor
  • S-100 board testing with Z-80 ICE
  • Donner 3500 - an early portable computer
  • Digital (DEC) PDP 11/05 NC Assembly
  • Univac 1219 rescue
  • IMSAI 1.4 BASIC vs. MITS 8K BASIC
  • Fido BBS listing node list 6-13-1986
  • PDP 8e
  • MITS 88-2 SIO (2SIO) for BASIC
  • Visual Technology Inc Model 1050
  • Amiga 2500 Restoration
  • The Evolution Of IBM Computers
  • Replacement teletype print hammer head
  • Archiving and Copying Software 101
  • Computers Built 1940 - 1950
  • CBM B-520 (a.k.a B256-80 or B500 256)
  • RCA COSMAC Microkit
  • Commodore 64K C-116 Mods
  • MITS 8800b Turnmon 9600 baud
  • Catweasel, 8in and 5 1/4
  • Raspberry Pi as Gateway to Internet
  • Digital PDP11 late 1969 early 1970
  • PDP 11/40 72 inch cabinet model
  • PDP 11/40 Industrial 11 model
  • Digitial MicroVAX 3100 30 System
  • Digital VAX 4000-200
  • Commodore 64 / 1541 DRIVEKNOCK
  • Booting the System Using RL02 drive
  • PACS: Reflections by Kathleen Mauchly
  • Tele-Graphic Computer Systems Inc.
  • Commodore B Series SID Jukebox?
  • Installing Core into PDP 11/40
  • Setting Up OpenVMS 7.1 DNS CLERK
  • Felt-Tarrant Comptometer Model J
  • NextStation Color
  • Digital Rainbow (PC100-B2)
  • 1970 Compusad Compulogical Tutor
  • Archiving Papertapes Using DSI NC 2400
  • 1976 P.C.C. Features the MAI JOLT 6502
  • 1961 Beckman DEXTIR Computer
  • UNIVAC 1 and UNIVAC File Computer 1
  • Past Issues:


    processor tech processor tech sol20

    This image was selected at random from the archive. Click image for more photos and files from this set.