ALF Music Card
ALF Music Card
The ALF Music Synthesizer System
Monday, September 24, 2012
One of the earliest add-on cards for the Apple ][ was the ALF Music System card. Consisting of a crystal oscillator, an Intel triple timer chip used to generate the three tones, and three 16-bit multiplying DACs to control volume and create the Attack, Decay, Sustain, Release envelope of each note, it produced square waves at 65532 pitches and volume levels. That resolution is good enough that the ear can’t hear individual steps. Here’s a sample.
Music is composed in the ENTRY program which puts a grand staff on screen and you use the game paddles. One paddle selects what’s being entered, rest, note, sharp, flat, step forward or back, etc. from the row below the staff. The other paddle places the note vertically on the staff, and pressing a firing button drops the note into the score. Sounds complicated, but with a little practice, it goes pretty quickly. Matters are helped with features such as subroutines, and since music is filled with repeats, those come in very handy.
The PLAY program puts a blue bar across the screen for each voice in the score with a yellow dot to mark middle C. The note being played moves left (bass) to right (treble) and changes color with loudness. The first game paddle is used to adjust playback speed or tempo, and pushing the firing button starts playback.
A program called DISCO creates sets or playlists.
The original ALF system used up to three of the three-voice cards. Later when the Texas Instruments sound chip became available, a 9-voice ALF card was developed which was less expensive than the original and produced white noise as well as square wave tones. The T.I. chip was less refined, having less resolution in both pitch and volume, but was so much cheaper that it accounted for most sales.
The first add-on music card for the Apple ][ was the ALF. Offering three voices with a high-resolution graphical user interface featuring a grand staff on which you placed notes using the game paddles, it was very sophisticated for the day.
Update September 2016: (No longer available)
There is a kit available on fleaBay to build a copy of the 9-voice ALF card. I haven’t seen the kit, but it looks like the real thing. ALF is a great way to do music on the Apple II. There’s lots of music out there, and it’s easy to program your own.
http://www.ebay.com/sch/plamenvaysilov/m.html?item=152247959912