Sequential Circuits Prophet-5 Service Manual - Audiofanzine

I \An additional, simple change was made to the CPU which has absolutely no effect onoperation, U31 1-25 -BUSRQ is a CPU output which in REV 3-0 was tied high. In Rev 3.1this pin ispulled high through R315^ for optional use with factory test instruments,503^2 shows how TP30^ was added toU32^-10 ADC BUS DRIVER, pulled low throughR3155. Tying this point high starts the memory test routine, as discussed in Section 11.8-2 REVISION 3.2 COMPUTER and USARTRev 3.2 was created to interface with the Model 1005 Polyphonic Sequencer and Model1001 Remote Keyboard/Controller. In order to arrange the interface, the operatingsystem was again expanded and communication circuitry added. Changes were alsomade to the Common Analog circuitry to accomodate PITCH and MOD CV inputs (seepara. 8-3).See BD051 Rev 3.2 Interconnect Diagram. J17 DIGITAL INTERFACE jack on the backpanel is a ^-pin Switchcraft SL-i7-^F, SCI #3-053. To mate, use SL-^0-4M, SCI //P-053.This jack is cabled along with ANALOG inputs from J 16 (see below) through J 15, toadded connector P305. SD351 shows the DIGITAL CABLE destination, U386 SIGNETICS2661 Programmable Communications Interface. This USART exchanges data with acompatible transciever over three lines as specified below. System interface programmingis discussed in Section 9 (as well as in the current Prophet-5 Operation Manual,CMldOOC.l).WARNING! This is not an RS-232 interface. It uses 5-V TTL levels. RS-232 voltagelevels (+/- 12 or +/-15V) will most likely blow the two input gates. Furthermore, mostRS-232 interfaces lack the speed required for transparent sequencer-Prophet communications.Pin 1, GROUNDPin 2, CLOCK TO SYNTHThis input sees pin 2 of a 7^LS08 (U385-3), with a lOK pull-up to +5V. Note that thetransmit and receive clocks (TxC, RxC) are tied together. Maximum frequency: 625kHz. Minimum clock frequency for "transparent" real-time sequencer operation dependson exact operations involved. Slower speeds will generally degrade performance bycausing the Prophet to wait too long for the sequencer to complete multi-byte datatransfers. 50 kHz is probably as slow as anyone is likely to find useful.Pin 3,DATA TO SYNTHThis input sees pin ^ of a 7^LS08 (U385-6), with a lOK pull-up to +5V. Data format isdiscussed in Section 9.Pin ^, DATA FROM SYNTHThis is a M05 output direct from pin 19 of the Signetics 2661 USART. The driver Lowoutput voltage (Vql) isspecified at O.W max. with a 2.2 mA output current (Iol)- Thedriver High output voltage (Vqh) is 2.W min., specified at -^00 uA (Iqh)-Digital Cable Specificationsing used depends on the distance desired between units, and upon the noisepresent in the system environment. Using individual coaxial cables for the two data andclock lines will work best. It is likely you could have trouble-free operation at 20-ft orlonger. Three-conducter coax will probably work up to 10 ft. Single wires may be used8-2TM1000D.2 10/81