My reply follows quoted text. Michael ha escrito:
> I need to know if anyone knows how to build a device to allow me to > connect a PS/2 keyboard and mouse to my classic II. I have searched for > such devices and found the prices rediculus. I am sure it is something I > can build myself with the proper pin-outs, and instructions on what is > to be done with the two additional wires in a PS/2 device... First of all, I'd like to apologize: this e-mail has gone a bit out of topic. But I think that the question applies to all compacts (except the 128k, the 512k/512ke and the Plus) and the answer can be interesting. I do not think that you can build a PS/2-to-ADB converter just by soldering a couple of connectors. PS/2 and ADB protocols are very different. PS/2 is a variation of the original PC keyboard protocol (the same signals in a different plug), that in turn is derived from IBM terminal's keyboard connector. It uses an asynchronous protocol with two data lines (one in each direction) designed to support only one device (that's why you *need* two PS/2 connectors on the computer, one for the keyboard and other for the mouse). ADB, instead, has only one bidirectional data line that is arbitred by a far more complex protocol in a way that allows up to fifteen devices (plus the host) to be connected to the bus and communicate with each other. Taking an 8-bit microcontroller (for example, an Intel 8049 like those used in PC keyboards or a Motorola 6804 like those used on the pre-SE Macintosh keyboards) and programming it to make a bridge between an ADB bus and two PS/2 connectors wouldn't be difficult nor expensive if you know the microcontroller's aseembly language and the ADB and PS/2 specifications, but will require a lot of design and implementation work. Commercial production is a different thing: if you shell something, you don't have to charge only for the materials used to build it. You have to cover also the design costs. And in a device that can take quite a time to develop and that few people is interested on, that means that the price won't be cheap. Even if an 8049 microcontroller, three mini-DIN connectors, a printed citcuit board and a plastic case for it aren't the most expensive things in the world. Greetings, Antonio Rodr�guez (Grijan) <ftp://grijan.cjb.net:21000/> -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
