This is the relationship between the indicator panel cable slots in the backplane for the RF11, and the sections of the indicator panel display for that controller: A31-1 Top left A31-2 Second left A32-1 Third left A32-2 Bottom left B31-1 Top right B31-2 Second right B32-1 Third right B32-2 Bottom right Here is the actual light pattern (unused lights are marked with '-'): XXXXXXX--XX--XXX-XXXXXXX-XXXXXXXXXXX X-X---X-X-X--XXX---------XXXXXXXXXXX X-X-X-X-X-X--X-X----XXXXXXXXXXXXXXXX X-X-X-X-X-X-X---X---XXXXXXXXXXXXXXXX Here are the detailed contents of the left four rows of lights (top to bottom), and then the right four rows. Signal names are from the RF11 prints; meaning is from the RF11 writeup in the Peripherals handbook (if un-marked), from the prints (if marked '[]'; '{}' marks additional explanator material added to make things clear). Caption (where it differs from the signal name) is taken from the drawing of the indicator panel in the RF11 manual (DEC-11-HRFD-D). Captions of the form 'XXX-N' are intended to have the label above the bar, and the digits below. Parts of the CSR are in the upper left; Signal Caption Meaning ERR STATUS-ERR Error FRZ STATUS-FRE Hard error WCE etc Write Check Error DPE Data Parity Error NED Non-Existing Disk WLO Write Lock Out MXF Missed Xfer - - EX1 XM-01 Extended Memory bits EX2 XM-00 - - DA02 DISK ADDR- DA01 DA00 - TA06 TRACK ADDRESS DISK FLAG FLAG-DISK Controller error condition - DATA RQ FLAG-DATA Controller doing DMA - - - INT ENA Interrupt enable - OFLO {Word Count} Overflow - ~ CNTR BSY RDY {Controller ready to accept command} - - MA PARITY-MAIN F15V PARITY-F1 F05V PARITY-F0 - - DA03 NED-DOFL Drive Overflow - SEQER NED-SEQ Sequence Error - PSLER NED-PSEL Program Select Error - CMA INH Current Memory Address {Increment} Inhibit - WRITE {Controller writing to disk} - DISK RUN {Controller interacting with disk} - - APAR PARITY-ADDR Disk address parity - DPAR PARITY-DATA Disk data parity - - APE HDWR ERR-APE Address Parity Error - MNEP HDWR ERR-MN Missing Negative pulses - MPEN HDWR ERR-MP Missing Positive pulses - BTER HDWR ERR-BT B Timing track error - CTER HDWR ERR-CT C Timing track error - DTER HDWR ERR-DT D Timing track error - NEM HDWR ERR-NEM Non-Existing Memory - - - DRL Data Request Late - TA05 TRACK ADDRESS TA04 (continued from TA03 TA06 above) TA02 TA01 TA00 - WA10 WORD ADDRESS WA09 WA08 WA07 WA06 WA05 WA04 WA03 WA02 WA01 WA00 - - - - - - - DS10 DISK SEGMENT DS09 DS08 DS07 DS06 DS05 DS04 DS03 DS02 DS01 DS00 - - SR15 SHIFT REGISTER SR14 SR13 SR12 SR11 SR10 SR09 SR08 SR07 SR06 SR05 SR04 SR03 SR02 SR01 SR00 - - BR15 DATA BUFFER REGISTER BR14 BR13 BR12 BR11 BR10 BR09 BR08 BR07 BR06 BR05 BR04 BR03 BR02 BR01 BR00