9914V TAPE UNIT

'.JR I TECENTRE T ,J.,p I 'I--~~~~------'!P~R PA:LS ERASE- I '"'RITE OI",R \..;RiTE --------------'1 :_ PVR i='A I L CONTROL ERr,5E-PROC OK"'TNG____ ~~ ____ '_ ___ P_O_V_E_R ____ ~ I HEADS I~T"'RITECURRENTSTEP ClK9 \lOIN 0-7,;PEDESTAL CURRENT CONTROLSTEP CURRENT CONTROL)l9"'RITEDRIVERS"'REF1[ [8 DAC DATAADP CONTROL~)OAC·,I CONTROL DACCONTROLBUFFERS~-CD-1:Z-l1JI-ā:::::J2.4.2.2 Current DefinitionFIGURE 2.4.2(a) ADP WRITE BLOCK DIAGRAMThe shape of the write current waveform can be controlled to give either a step andpedestal (in GCR) or a square wave (OPE. PE and NRZ), see Figure 2.3.2(b). Theamplitudes of the step and pedestal are separately controlled by voltages from the writecontrol DACs. The timing of the step is controlled by the STEP _ClK signal from the DDPboard. The write drivers can be inhibited by a single logic signal, allowing separateswitching of the write current and erase currentHead current is drawn from the + 12V rail and returned via a dedicated ground.9914V Servicing Manual 95 124766 (Draft Issue A)