From HippieHatBrainParasitemr808@teleport.comSun Mar 26 11:26:32 1995 Date: Tue, 26 Mar 1985 10:41:04 +0000 From: HippieHatBrainParasitemr808@teleport.com To: analogue@hyperreal.com Cc: 72617.2125@compuserve.com Subject: Notes on the ChromaFace I've been wanting to know more about the computer interface on the Chroma/Chroma Polaris. Does ANYBODY have ANY information about its command structure? I'd like to know just what's possible w/ the Chromaface. Also, has anyone EVER been able to control a Chroma from a Polaris? I typed in the following article about the Chromaface, which is the sum total of what I know about it. It's pre-MIDI, and apparently much more capable than MIDI. I get the feeling that if the Chroma designers had been in control of the MIDI committee, instead of SCI's Dave Smith, we would have had many cool features, like commands to access floppy/hard drives over MIDI. Oh well, maybe ZIPI will be cooler. This came out of the August '83 POLYPHONY: FENDER'S TRIAD INTERFACE The Chroma Keyboards division of Fender musical instruments has introduced a new instrument interface bus, called Triad (TM). This system lets users connect instruments to computers via a 25-pin D-connector cable; multi-instrument connections can be made by using one Tridad device (for example, a Triad-equipped computer) as a star-network controller. Triad-equipped instruments will have two uni-directional 8-bit parallel ports (one output, one input) and two handshaking lines for each port. This structure is intended to provide extra flexibility in the way that a Triad system responds to data. The handshaking lines can be polled or used to interrupt the Triad device. The software characteristics of the Triad interface make it unique among instrument interfaces. Multi-byte operating commands are transferred across the bus, and the receiver interprets and acts upon those commnads. All Triad-equipped devices that produce musical sounds are organaized as logical instruments. The number of logical instruments available in the device can be communicated through the Triad interface. The instrument consists of "channels" assigned to it and a data structure defining the sound of that instrument. The channels are the actual sound generation modules in the Triad device. The total number of channels available can change (due to adding expanders, etc.) and be communicated through the interface. The number of channels allocated to a particular instrument can be controlled through the Triad interface or automatically set by the Triad device when the instrument is defined. All Triad-equipped devices are capable of receiving data to be acted upon at a future time. This is accomplished by using relative time commands. Each command can be preceded by a time command that tells a Triad device when to execute the command (relative to the last execution in that logical instrument). The time command values are in increments of 1/192 notes. Time synchronization between Triad devices is accomplished by beat commands that are sent only when the time base should be changed. All Triad devices are capable of time stamping the commands representing performance and panel events. That is, the device can simulate a recorder or sequencer. The commands which control thes functions are standardized and accessible from the Triad interface. The Triad command structure permits device-dependent data to be transferred over the interface. A program that defines a sound, for example, can contain information useful to that particular device. The structure of other device-dependent command functions (such as the SERT PARAMETER function on a Chroma Polaris synthesizer) is standardized. But what the device actually doews with this data is device-dependent. For example, SET PARAMETER 3 TO 0 could mean "set the keyboard alghorithm to polyphonic" in a Chroma-type synthesizer; or "set the modulation index to 0" in a digital synthesizer. Also an escape command sequence is available for use with device-dependent functions to be developed in the future. The Triad interface also provides other functions including "peeking" and "poking", or otherwise interrogating or changing the device's internal workings. Any cassette interrface that the device controls can be accessed over the Triad interface. And commands relating to interface data flow control are also available. From ac151@freenet.carleton.caMon Apr 3 11:02:29 1995 Date: Sun, 26 Mar 1995 15:35:03 -0500 From: David Clarke To: analogue@hyperreal.com Subject: Re: Notes on the ChromaFace >I've been wanting to know more about the computer interface on the >Chroma/Chroma Polaris. Does ANYBODY have ANY information about its command >structure? Yes - what specifically did you want to know? >I'd like to know just what's possible w/ the Chromaface. Well, with respect to the Polaris, you can do everything you can over the MIDI port, plus more. With the Chroma, you can take control of just about everything inside it. In effect, you can control all the panel controls (sliders, buttons, etc.) as well as have special control over internal "data streams." Typically, you can peek and poke into memory locations of the "instruments" as well into things like the sequencer data stream and into any arbitrary memory locations (did you ever want the display on the Chroma to say "HI DAVE" - well write to location 0020 - 0029 and you can do that ...) You can start cassette controls, inquire about working boards, find out what the current setting of any parameter is (useful on the Polaris because you nver quite know there that darn slider is ...) Both machines contain major and minor "loop hooks" that, theoretically, you can use to hook in additional controlling code. For the polaris, this interface offers additional advantages. If under midi control, volume can only have a value from 0-127. Via the Chroma Port, volume is actually expressed as 0-255. >Also, has anyone EVER been able to control a Chroma from a Polaris? Yep - as a matter of fact, my Chroma and Polaris are connected together right now. You can use the Chroma to control the Polaris or vice versa. Also, you can set things up so that, for instance, the Polaris will play the "main" sound, with the Chroma playing the "link" sound. You can also use the the sequencer in the Polaris to record/play data on the Chroma (you can not, however, use the Polaris as a MIDI -> Chroma interface box :-< ). I've also made a little box to allow the Chroma and/or the Polaris to talk to my computer (IBM) via a serial port - it's not MIDI, but it does allow me to "get inside" both machines and fiddle around. -- ------------------------------- /''' -------------------------------- David Clarke c-00 davec@rflab.ee.ubc.ca ac151@Freenet.carleton.ca > clarkec@sfu.ca ------------------------------- - --------------------------------