Altair Music of a Sort
IT WORKS!
I received my ALTAIR 8800 in the mail at 10 am, and 30 hours later it was up and running with only one bug in the memory! That turned out to be a scratch in a printed circut land that took 6 more hours to find. After that was fixed, everything worked!!
Now, what do you do with a machine that so far has no I/O boards or peripherals?? Well, there's always the front panel switches and machine language, so I was soon busy making up programs to test all of the 8080's functions; and getting a good set of caluses on my ten input devices! There's a lot of 8080 instructions!!
ZZZIIIPPP!
I had just finished setting in a 'sort' program, and at the same time I was listening to a weather broadcast on a little transistor low frequency radio, which was sitting next to the Altair. I hit the 'run' switch on the computer and it took off sorting the same list of numbers over and over again.
At the same time my radio also took off !!
The computer was sorting numbers and the radio was going ZZZIIIPP! ZZZIIPP! ZZZIIIPP!!!
"Well what da ya know! My first peripheral device!!!"
The radio was picking up the switching noise of the 8800! I tried some other programs to see what they sounded like, and after about 8 hours of messing around I had myself a program that could produce musical tones and actually make music; of a sort. (Or any other program you have!)
MUSIC!
The closest sheet of music that I could find was "THE FOOL ON THE HILL", by the Beatles, so I translated it into OCTAL code, picked up the Altair, and headed down to Menlo Park for the 3rd meeting of the `BAACUG-HBCC'.* I thought everyone there should see just what a computer can do!
* Initalization of "BAY AREA AMATEUR COMPUTER USERS GROUP-HOME BREW COMPUTER CLUB"
RECITAL!
This being the Altairs' first recital , it was a bit shy at first, and refused to power up. (Even though Freds tape recorder was plugged into the same wall outlet and working just fine.) One forty foot extension cord and half an hour later we were ready. Freds tape machine turned out to be running on its own battery power, and all of the wall plugs were dead!
The recital then proceeded with nary a glitch, much to everyones delight. (Although during the demanded encore, the machine did break into its own rendition of 'Daisy's apparently genetically inherited.)
PROGRAM TO MAKE AN ALTAIR 8800 PLAY MUSIC
000 LXI H 041
001 b2 xxx - ADDRESS OF FIRST
002 b3 xxx DATA ENTRY
003 MOV A,M 176
004 CPI 376
005 b2 377 - START OVER DATA
006 JZ 312
007 b2 000
010 b3 000
011 MVI D 026
012 b2 xxx - TEMPO DATA
013 DCR B 005
014 JNZ 302
015 b2 020
016 b3 000
017 MOV B,M 106 TO RUN THE PROGRAM:
-------------------
020 DCR C 015 To run the program, push the 'RESET' switch,
021 JNZ 302 then push the 'RUN' switch.
022 b2 013 To stop the program, push the 'STOP' switch.
023 b3 000
024 DCR D 025 TO MAKE YOUR OWN MUSIC:
025 JNZ 302 -----------------------
026 b2 013 Begin loading your music data anyplace after
027 b3 000 address 034. Be sure to load the starting address
030 INR L 054 into H&L at address 002, 003.
031 JMP 303 Each data entry will be one beat of music.
032 b2 003
033 b3 000
OCTAL CODES FOR NOTES
---------------------
C 252
C# 240 LOW OCTAVE
D 230
D# 220
E 211
F 200
F# 172
G 162
G# 154
A 146
A# 140
B 132
C 125
C# 120 MIDDLE OCTAVE
D 114
D# 110
E 105
F 100
F# 075
G 071
G# 066
A 063
A# 060
B 055
C 053
C# 050 HIGH OCTAVE
D 046
D# 044
E 042
F 040
F# 036
G 034
G# 033
A 031
A# 030
B 026
C 025
Q 002 Note; This is the quietest of the data notes.
It can be used for spaces and rests.
You may also like to put a number of
these quiet 'notes' at teh end of the
music data, to give a space between playings.
Data For "THE FOOL ON THE HILL" Beatles
Address Data Address Data ------- ---- ------- ---- 040 105 120 055 041 105 121 053 042 125 122 071 043 100 123 066 044 071 124 100 045 063 125 071 046 063 126 071 047 063 127 100 050 071 130 071 051 063 131 066 052 055 132 066 053 053 133 071 054 053 134 100 055 055 135 100 056 071 136 100 057 063 137 071 060 046 140 066 061 046 141 060 062 046 142 060 063 071 143 066 064 063 144 071 065 046 145 066 066 046 146 066 067 053 147 060 070 042 150 053 071 046 151 046 072 046 152 046 073 063 153 046 074 071 154 046 075 063 155 044 076 053 156 046 077 053 157 053 100 063 160 053 101 053 161 053 102 071 162 053 103 063 163 053 104 063 164 002 105 071 165 002 106 063 166 002 107 046 167 377 110 046 111 046 112 053 113 042 114 053 115 046 116 046 117 053
Data for "DAISY"
Address Data Address Data ------- ---- ------- ---- 170 034 250 040 171 034 251 042 172 034 252 046 173 042 253 034 174 042 254 034 175 042 255 042 176 053 256 046 177 053 257 053 200 053 260 053 201 071 261 053 202 071 262 053 203 071 263 046 204 063 264 042 205 055 265 042 206 053 266 053 207 063 267 063 210 063 270 063 211 053 271 053 212 071 272 063 213 071 273 071 214 071 274 071 215 071 275 071 216 071 276 071 217 071 277 071 220 046 300 053 221 046 301 053 222 046 302 042 223 034 303 046 224 034 304 046 225 034 305 071 226 042 306 053 227 042 307 053 230 042 310 042 231 053 311 046 232 053 312 042 233 053 313 040 234 063 314 034 235 055 315 042 236 053 316 053 237 046 317 046 240 046 320 046 241 042 321 071 242 046 322 053 243 046 323 053 244 046 324 053 245 046 325 053 246 046 326 002 247 042 327 377
NOTES:
TEMPO;
The tempo is controlled by the value in address 012. Start out by trying 040.
TO PLAY BACKWARDS:
Put 377 in front of all music data.(to cause looping)
Change address 001 to read the END of the music data.
Change address 030 to DCR L (055).
TO PLAY ALL OF THE MEMORY:
Change address 001 data to a NOP (000)
Change address 004, 005, 006 to NOP (000)
This will cause program to read all of the memory, including the program instructions themselves.
RADIO INFORMATION:
A low frequency radio around 330 KC works best, but any AM radio will pick up the music at quiet places on the dial.
Set the radio on or very close to the computer, start the program, and turn the dial on the radio until you get good sound. Some places will be much better than others, and some will pick up different sounds from the computer. Also, try moving the radio to different positions on or around the computer. Just rotating the radio 90 degrees can make a lot of difference in the sound you will get.
With a little experimentation, you can make all kinds of interesting sounds. ie;sirens, ray-guns, etc.
Steven Dompier