Guitar Hero for the Apple II


Filed under Hacks & mods, Software showcase;
8 comments.

This week at the WWDC, the iPhone 4.0 was unveiled, and with it, several new apps, including Activision's own Guitar Hero, a music rhythm game that first debuted on the PlayStation 2 and allows players to use a plastic guitar to strum along to on-screen color-coded symbols. Games in the Guitar Hero franchises have sold over 40 million copies, warranting its first appearance on an Apple platform.

It's encouraging that an entire genre has sprung up around a game's audio component. Game soundtracks have often taken the backseat to visuals, which is unfortunate; years after we last play a game, it's the melodies that we remember best, rising unbidden to our whistling lips. Apple IIGS users are especially fortunate to have enjoyed this element of the gaming experience, as the machine's Ensoniq sound chip performed far better than stock IBM clones of the era. I have a Soundmeister sound card in my IIGS, though I don't recall exactly what benefits it bequeathed; all I remember is that, even prior to that upgrade, my DOS-based friends were jealous of my computer's capabilities.

With all that aural processing power, I can't help but wonder why the iPhone has Guitar Hero but the Apple II doesn't? Turns out, we do:

Guitar Hero for the Apple II

Guitar Hero for the Apple II!
Image courtesy Mac-TV.

This advertisement is for a sound card that Steve Weyhrich's Apple II History site describes: "ALF Music Card (ALF Products, Inc.) was strictly a music synthesizer, with some included software to aid in producing the music." This card, released in the early 1980s, was outclassed a few years later by the Apple IIGS. But in theory, both 8- and 16-bit model of Apple II should be capable of a Guitar Hero-like game, sans peripherals. It requires playing music and accepting input simultaneously, but also matching the accuracy of the input with the time of the music. That too shouldn't be difficult: the input routine doesn't need to be aware of the music, so long as it has its own counter by which to judge input. (Five seconds into the game, it looks for the letter 'A'; six seconds in, it'll accept only 'F'. etc.) If the keyboard input and sound output routines were in fact separate, then the former wouldn't even be complicated by the latter using Vince Briel's MP3 peripheral. Even barring that, there are so many chiptune artists who use the Apple II to create original or remix songs that assembling a sweet soundtrack should be trivial. On the visual side, it's already been proven that the Apple II can produce music videos in time with external audio, so such a game could truly be a complete package.

Has anything like this been done before? Since music rhythm did not emerge as its own genre until the 1990s, I can't think of any software titles that predate that label which would nonetheless suit it. Are there Apple II games that rely predominantly on sound to prompt user input? If not, why not?

(Hat tip to dangerman and Mac-TV)

  1. That is a great ad! Where did you find it?

  2. Thanks, Steve! The image was posted to Web site Mac-TV last summer. I've updated the photo's caption to make this attribution more obvious.
     
    I don't know much more about the ad itself; you can read what I found on the second page of this blog post.

  3. Bill Fickas says:

    The Net is amazing :D This is Bill Fickas live. I worked my way through college at ALF Products until 1983 when I graduated and continued to work there as an engineer until the place closed at the end of 1995.

    Sadly, the "Guitarple" was just a mock-up for the ad. We bought an electric guitar from a pawn shop and pulled off everything but the body. The Apple itself was unharmed except for cutting holes in the case to mount the guitar parts.

    I put on my tightest jeans, my poofiest shirt and mirrored shades that belonged to one of the bosses. The guitar strap was from my own personal acoustic guitar. I got to stand under photographer's lights waving that thing around and screaming while pix were taken.

    The point of the ad was to make fun of the outrageous claims of some of the competition. There's a bunch of quotes taken from them followed by the tag line like: "Sure. You've read their claims, now listen to their music." The joke was that one of the claims was actually ours from another of our ads.

    We printed some copies of the ad on some card stock. I still have a stack of them somewhere.

    -Bill Fickas

  4. Ralph Hyre says:

    Bill, thanks for posting!

    I'd love to get a schematic or parts list for the early ALF music cards for the Apple ][. The earliest ALF Card seemed to have an 8-octave range, and I'm trying to build a replica, since I already have the other card that was common with early Apple pre-MIDI-era synths (Syntauri and Passport), the Monutain Computer Music System Card.

    All I have to go by is a poorly-copied manual for cloners of sorts, called "Apple Seed" by Ray Kosmic. http://www.classiccmp.org/cini/pdf/random/Apple-Seed%20-%20Ray%20Kosmic.PDF… Guide 8-6 on page 101 lists a card with a 74LS

  5. Bill Fickas says:

    Hi Ralph,

    As far as I know the schematics no longer exist. When ALF was sold to Rimage in 1993 they didn't want the documentation on any old products and it all got thrown out.

    The documentation you pointed to is indeed the chip layout and parts list for the original Apple Music Synthesizer (AMS) card although the card pictured looks like it's a wire-wrap or prototyping card and not one of our printed circuit boards.

    The cards would not do you much good w/o the original software which had all the timing and sound envelope generation. My first jobs at ALF were assembling those cards and then diagnosing bad ones so I can certainly give you and overview of how it worked.

    The 8253 part is a 3 channel programmable interval timer. It was/is a standard Intel part and was the time base part for the original IBM PC. The same logic is still in all Wintel computers. We used it in Mode 3 to generate square waves. The crystal on the board was the time base to the 8253 and chosen to divide up well into the base octave of the evenly tempered (chromatic) scale (that's 12 notes in a row on a piano keyboard counting both white and black keys, after which is repeats.)

    The square wave output from each channel of the timer chip fed into the sign bit selection of one of the 3 DAC76 digital to analog converter chips. The ADSR (look up ADSR in Wikipedia) volume waveform was generated by the software and clocked into the octal buffer chips which then drove the input of the DACs. The three DAC outputs were summed on the input of the op-amp and then presented on the output connector.

    Using a single card gave monaural output (identical on two RCA cables.) Two cards gave three channels each of left and right. Three cards could be combined with three left, three right and three left+right (middle) channels.

    All of the timing of tones, generation of divisors for the timer chip and computations of volume were done by the software. This is quickly discovered if you stop the software abruptly with the power since the cards would keep blaring away with the last notes and volumes they were sent :D

    The music entry system was for quite some time the largest piece of assembly code written for the Apple ][. As far as we know it is also the very first "point and shoot" entry system on an Apple product, predating Mac (and Lisa.) The game paddle acted kind of like an Etch-a-Sketch version of a mouse with one paddle controlling horizontal selection of which sort of note to be entered (half, quarter, rest, etc.) and the other paddle selecting the vertical position on the musical staff.

    Another interesting bit of trivia about the assembly software is that it was not written on an Apple! It was assembled from paper tape source on a cross assembled running on an Imsai 8080 machine. The AMS actually predates the introduction of the the floppy drives and originally came on cassette.

    When the floppy drives came we needed to release a disk version. We found out that the COPYA program provided by Apple did such a poor and slow job of duplicating disks that we wrote our own duplication software. That is what ultimately lead ALF to become a leader in floppy disketter duplication services and equipment, but it was all a by-product of the music cards.

  6. Thanks! My search for old parts will be easier with the proper part # – DAC76 produces much more useful information than 8227DP.

    http://www.chipsetc.com/pmi-precision-monolithics.html

    I was making a bad assumption that the 74LS624 VCO was generating an audio waveform, when it sounds like it's just interacting with the 8253 chip.

    "Computer Parts Galore" and other companies were actively cloning the whole Apple II and IBM PC ecosystems in the mid-to-late 1980s. They advertised in "Computer Shopper", and you could buy bare PC boards from them for $10 or $20, then add the components yourself.

    It appears that the AM6070 (AMD) was developed as a pin-compatible replacement for the DAC-76 "companding A/D converter", using u-Law compression. That's how the original MC-1 cards squeezed 78db of dynamic range into 8 bits of input (at the expense of some noise) compared to the later MC-16 cards. Too bad the Mountain Computer guys didn't use this in their design – they appear to use the AM6080 part, a linear DAC.

    Oberheim and a couple of others used companding DACs in their gear, as well.

    Very cool! Thanks again!

  7. Bill Fickas says:

    Yes, the 624 just works with the xtal to provide the frequency base for the 8253. The 8253 is superseded now by the 8254 and the DAC76 by the DAC86. The datasheet you found is exactly the DAC. We used is because it was companding for logarithmic volume control and because the telecom people used it, it was available and affordable.

  8. Bill Fickas says:

    Hi,
    I just got a message from the president and founder of ALF (we keep in touch) who came across this series of posts. He let me know that the schematics for the musics cards are available in the documents here:

    http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Interface%20Cards/Audio/ALF%20MC1%20MC16/Manuals/

    Enjoy!