User manual BOSS DR-55 SERVICE MANUAL

[. . . ] 21, 1980 1 RS FLIP FLOP (2/4 IC3) (a) PLAY Mode When the START switch S5 is turned ON, the Q cutput goes to H and triggers the Clock Generator (2). [. . . ] 5 DUAL BINARY COUNTER (IC2) This circuit counts pulses from the clock generator (2) in PLAY mode, and counts pulses from the Schmitt trigger (3) in WRITE mode, and then outputs binary-coded signals from the terminals Ql-Q5; Ql-Q4 denote 16 steps composing each rhythm. Signal from Q5 is applied to A7 only when the VARIATION switch is set to AB. To the terminal A7, the L level voltage is given when the switch is set to A and H when switch is set to B. DR-5 5 6 256 x 4 BIT CMOS MEMORY (IC1) Reading/writing from/to this memory is as described below. The upper 3 bits designate rhythms 1-8, the next one bit designates VARIATION A and B, and. The memory functions only when the clock is H, and outputs H's or L's from DO 1-4. (When the clock is L, DO 1-4 becomes high impedance. ) In WRITE mode, when the terminal R/~W becomes L, a data from the flip flop is written in one of DI 1-4 via Sl. A previously stored data is rewritten from DO via R61-R64 to the remaining three DI's. [. . . ] The DO l pulse can be externally outputted through the CSQ jack. When this jack is enga. ged, however, the ACCENT function of the DR-55 proper becomes invalid. [. . . ]