==Phrack Magazine== Volume Four, Issue Forty-Two, File 8 of 14 USEFUL COMMANDS FOR THE TP3010 DEBUG PORT BY G. TENET ALL OF THE COMMANDS LISTED BELOW, INDICATE A LENGTH IN ALL THE READ COMMANDS. THE LENGTH OF THE READ COMMANDS MAY VARY DUE TO CONFIGURATION OPTIONS AND SOFTWARE VERSION. 1) L7FE,L,A,R200 THIS COMMAND STRING WILL LOAD '7FE' INTO THE MEMORY POINTER REGISTER THEN LOAD THE CONTENT OF '7FE' AND '7FF' INTO THE MEMORY POINTER REGISTER. THE 'A' THEN INCREMENTS THE CONTENTS OF THE MEMORY POINTER REGISTER. THE 'R200' COMMAND THEN READS 200 BYTES BEGINNING AT THE LOCATION SPECIFIED BY THE MEMORY POINTER REGISTER. THIS AREA IS USED FOR STORING THE LOADED CONFIGURATION. DUE TO THE VARIABLE NATURE OF THE CONFIGURATION RECORDS, THE READ COMMAND MAY HAVE TO BE MODIFIED DEPENDANT ON THE NUMBER OF LINES DEFINED, THE TYPE OF LINES DEFINED (X780,3270) AND THE TYPE OF SOFTWARE LOADED (4.2X OR 5.0X). 2) LC4,R3,LCC,R3 (4.2X SOFTWARE) L124,R3,L131,R3 (5.0X SOFTWARE) THIS COMMAND STRING WILL DISPLAY THE BUFFER MANAGER CONTROL BLOCK AREA WHICH HAS BUFFER COUNTS WHICH MAY SUGGEST POSSIBLE PROBLEMS. 3) L32C,R (4.2X SOFTWARE) L29C,R (5.0X SOFTWARE) THIS COMMAND STRING WILL DISPLAY THE NUMBER OF ACTIVE VC'S IN THE TP3 AT THAT MOMENT. IF THIS COMMAND IS USED VIA THE LOCAL CONSOLE, THE VC COUNT WILL NOT INCLUDE THE USER CONNECTION BECAUSE THERE WILL BE NO VC ON THE X.25 LINE FOR THE LOCAL CONSOLE. 4) L70,R60 THIS COMMAND STRING WILL DISPLAY THE LCB (LINE CONTROL BLOCK) POINTER FOR THE CONFIGURED LINES. THE ORDER THAT THE LCB POINTERS ARE ENTERED ARE: CONSOLE LCB, X.25 LCB, LINE 1, LINE 2, LINE 3...LINE27. ANY ZERO ENTRY IS AN UNCONFIGURED LINE EACH LINE ENTRY IS TWO BYTES LONG. 5) L300,L,R20 (4.2X SOFTWARE) L270,L,R20 (5.0X SOFTWARE) THIS COMMAND STRING WILL DISPLAY THE LCN VECTOR TABLE. THE ENTRIES ARE FOR EACH ACTIVE LCN BEGINNING WITH LCN 0 THRU THE HIGHEST CONFIGURED LCN. A 0000 ENTRY FOR AN LCN WILL INDICATE THAT THE LCN IS NOT ACTIVE. A NON ZERO ENTRY WILL POINT TO THE DCB (DEVICE CONTROL BLOCK) OF THE ASSOCIATED LINE/DEVICE. 6) L1F1,L,R20 (4.2X SOFTWARE ONLY) THIS COMMAND STRING WILL DISPLAY THE PROTOCOL ID TABLE FOR THE CONFIGURED/SUPPORTED PROTOCOLS. THE FORMAT OF THE OUTPUT IS: 999999999999... -- ---- ! -- ! ---- ! ! ! !...............POINTER TO THE SERVER TABLE ***** ! ! !...................POINTER TO THE PROTOCOL SERVICE ROUTINE ! !......................PROTOCOL ID NUMBER ! 01 =ITI (RITI AND LITI) ! 4B =X780 ! 47 =NAP 3270 ! 09 =DEBUG !........................NUMBER OF ENTRIES IN THIS TABLE 7) L(ADDRESS OF THE SERVER TABLE),R20 THE ADDRESS OF THE SERVER TABLE IS FOUND IN #6 (ABOVE) THIS COMMAND WILL DISPLAY THE SERVER TABLE IN THE FORMAT: 99999999... -- ---- ! -- !................ THIS IS THE ADDRESS OF THE FIRST FREE DCB ! ! IN THE FREE DCB LIST. IF 0000 THEN THERE ARE ! ! NO FREE DCB'S FOR THIS SERVER AND PROTOCOL. ! !.....................SERVER NUMBER !.......................NUMBER OF ENTRIES IN THIS TABLE THE POINTER IN THIS TABLE , IF PRESENT, WILL POINT TO THE NEXT AVAILABLE DCB. WITHIN THE DCB, THERE IS A POINTER AT DISPLACEMENT 18 AND 19 WHICH WILL POINT TO THE NEXT FREE DCB. THE LAST FREE DCB WILL HAVE A POINTER OF 0000. THE FOLLOWING COMMANDS ARE USED WITHIN THE TP3 DEBUG PORT TO PERFORM THE INDICATED ACTIONS. ONLY THE TP3325 WILL SUPPORT THE [# LPU NUMBER] OPTIONS. THE USE OF THE [# LPU NUMBER] OPTION IS ONLY REQUIRED IF YOU WISH TO ADDRESS A DIFFERENT LPU NUMBER; EXCEPT FOR THE 'S' COMMAND WITH WHICH THE LPU MUST BE DEFINED. A SPACE CHARACTER MAY BE INCLUDED IN THE COMMAND AND THE COMMANDS MAY BE STACKED (EXAMPLE: L7FE ,L,A,R5,L#2,L 7FE,L,A,R5,L#3 7FE,L,A,R 5). THE TP3325 COMMANDS THAT DO NOT USE THE 'LPU' PARAMETER USE THE LAST ASSIGNED LPU NUMBER. (EXAMPLE: L#27FE,R2,L#17FE,R4) THE FIRST LOAD COMMAND ADDRESSES LPU 2 AND THE NEXT LOAD COMMAND ADDRESSES LPU 1. THE READ OF TWO BYTES IS READING FROM LPU 2 AND THE READ OF FOUR BYTES IS READING FROM LPU 1. A VALUE INCREMENTS THE MEMORY ADDRESS POINTER. (EXAMPLE: A5 OR AFFE2 OR A#2EF) B VALUE USED TO ENTER OR EXIT BINARY MODE. (EXAMPLE: B01 OR B00) C [# LPU NUMBER] VALUE USED TO WARM OR COLD START A TP3325 LPU (EXAMPLE: C00 OR C#300) OR USED TO WARM OR COLD START OTHER TP3. (EXAMPLE: C01 OR C#201) D VALUE USED TO DECREMENT THE MEMORY POINTER. (EXAMPLE: D18 OR DFFE5 OR D#4IFF) E STRING USED TO CHECK FOR A EQUAL COMPARE OF MEMORY DATA. (EXAMPLE: E00 OR E0F0304 OR E#20000) F STRING USED TO FIND THE FIRST OCCURRENCE OF A STRING. (EXAMPLE: F0F0304 OR F08080202 OR F#308080404) G [# LPU NUMBER] VALUE USED TO FIND THE ADDRESS OF A CONFIGURATION FILE IN MEMORY. THE LPU DEFINITION IN THE COMMAND DOES NOT CHANGE THE LPU ASSIGNMENT IN THE DEBUG PORT. (EXAMPLE: GFE OR G01 OR G#301) I [# LPU NUMBER] USED TO OBTAIN A LIST OF THE CONFIGURED LINE TYPES. (EXAMPLE: I OR I#3) K [# LPU NUMBER] [14 DIGIT ADDRESS] USED TO OBTAIN THE LCB, ADDRESS TABLE POINTERS AND LINE NUMBER ASSOCIATED WITH THE ADDRESS. (EXAMPLE: K31102120012301 OR K#2 311021250212) N STRING USED TO CHECK FOR AN NON EQUAL COMPARISON. (EXAMPLE: N0F0304 OR N08080202 OR N#1 0F) P [# LPU NUMBER] PORT NUMBER USED TO READ THE CONTENTS OF A SPECIFIC PORT REGISTER. (EXAMPLE: P45 OR P21 OR P#4 21) R VALUE USED TO READ MEMORY DATA. THE QUANTITY IS INDICATED BY THE 'VALUE'. (EXAMPLE: R18 OR R200) S [# LPU NUMBER] LINE NUMBER USED TO OBTAIN DATA SET SIGNALS FOR THE DEFINED LINE NUMBER. (EXAMPLE: S1 OR S#23 OR S) T (TP3325 ONLY) W STRING USED TO WRITE DATA INTO MEMORY. (EXAMPLE: W0E0304 OR W08080707) X [# LPU NUMBER] USED TO DISPLAY THE DIFFERENCE BETWEEN THE STORED CHECKSUM AND A CALCULATED CHECK SUM OF THE OPERATING SOFTWARE. THE LPU DEFINITION DOES NOT CHANGE THE LPU ASSIGNMENT IN THE DEBUG PORT. (EXAMPLE: X OR X#2) Y (TP3325 ONLY) RETURNS NCC LOAD ADDRESS FROM EPROM Z (TP3325 ONLY) CRASHES APB AND XPB. MAY HANG APB IF THE X.25 INTERFACE DOES NOT RESET. $ PORT A -- ENABLE AUTOCONNECT M -- DISABLE AUTOCONNECT B -- BUSY R -- RESET C -- CLEAR HARDWARE COMMANDS FOR THE TP3000 'P' COMMAND DISPLAYS THE STATUS OF A SPECIFIED PERIPHERAL INTERFACE DEVICE FOR THE CPU. FOLLOWING IS A LIST OF SOME OF THE MORE USEFUL ADDRESSES WHICH CAN BE BENEFICIAL IF TRYING TO RESEARCH A PROBLEM. THIS COMMAND IS A READ TO THE SPECIFIED DEVICE. DEPENDANT ON THE DEVICE BEING READ (THE ADDRESS), THE TP MAY CRASH. COMMAND INTERPRETATION ======= ============== TP3010 ------ P45 READ CONSOLE READ REGISTER (BIT 2 THRU 6 SHOW THE POSITION OF THE FRONT PANEL ROTARY SWITCH) BIT 0 = NOT TIMEOUT STATUS (SEE P47) BIT 1 = NOT PBRST STATE (SEE P47) BIT 2 = NOT RESTART BIT 3 = NOT MEMORY SAVE BIT 4 = NOT TAPE LOAD BIT 5 = NOT PROGRAM SAVE BIT 6 = NOT DIAGNOSTICS BIT 7 = NOT SYSTEM GOOD IF BIT 6 THRU BIT 2 ARE ALL SET (EQUAL TO 1) THEN THE FRONT PANEL SWITCH IS IN THE X.25 LOAD POSITION. P47 THIS COMMAND WILL CAUSE THE FRONT PANEL ALARM TO SOUND. P4D,P4D,P4D,P4D,P4D,P4D,P4D THE LAST RESPONSE WILL PROVIDE THE DOWN LINE LOAD EPROM REV. LEVEL FOR THE TP3010. EXAMPLE 43 = 'C' LEVEL TP3005 ------ P23 BIT 1 = 0 CONFIG MODE 1 RUN MODE 4.2X 5.XX COMMENTS ====== ====== =========================================== 70 70 LCB VECTOR TABLE 2 BYTES FOR EACH LINE IN THE TP. IF LINE IS NOT DEFINED , THEN ENTRY IS 0000. IF LINE IS DEFINED, THEN ADDRESS POINTS TO THE LCB (LINE CONTROL BLOCK) C0 120 BM CONTROL BLOCK C4 124 # CONTROL BUFFERS INITIALIZED C5 125 # CONTROL BUFFERS FREE C6 126 LOWEST # CONTROL BUFFERS (00 IS NONE LEFT) 12B POINTER TO THE CONTROL BUFFERS CC 131 # BLOCK BUFFERS INITIALIZED CD 132 # BLOCK BUFFERS FREE CE 133 LOWEST # BLOCK BUFFERS REACHED (00 IS NONE LEFT) 138 POINTER TO BLOCK BUFFERS 1F1 POINTER TO PROTOCOL ID TABLE 270 1F0 X.25 LCB 27E 27E # FRAMES DISCARDED 27F 27F # CRC ERRORS 280 280 # REJECTS SENT 281 281 # REJECTS RECEIVED 282 282 # T1 TIME OUTS 283 283 # COMMAND REJECTS SENT 284 284 # COMMAND REJECTS RECEIVED 285 285 # DISCONNECTS SENT 286 286 # DISCONNECTS RECEIVED 287 287 # SET MODE SENT 288 288 # SET MODE RECEIVED 289 289 # FRAME OVERFLOW RECEIVED 28A 28A # I FRAMES SENT 28B 28B # I FRAMES RECEIVED 2B0 230 DMA LCB 300 270 LCN VECTOR TABLE 29B MAX. # LCN'S 32C 29C # OF ACTIVE LCN'S 7FE 7FE POINTER TO THE END OF THE OPERATING SYSTEM. THE NEXT BYTE IS THE BEGINNING CONFIGURATION TABLES. 159 E9 TIME OF DAY CLOCK 159 E9 1/10 SECONDS 15A EA SECONDS 15B EB MIN. 15C EC HOURS 15D ED DAYS 15E EE DAYS DCB + 3 XX PACKET REC. STATUS BYTE#1 00 = READY 01 = DTE WAITING 02 = DCE WAITING 04 = DATA TRANSFER 08 = DTE CLEAR REQUEST SENT 10 = DCE CLEAR INDICATION 20 = DTE RESTART REQUEST 40 = DTE RESET REQUEST 80 = DCE RESET INDICATION DCB +18 XX POINTER TO NEXT FREE DCB VALID ONLY IF THIS IS A FREE DCB ITI SPECIFIC LCB INFORMATION LCB+27 PHYSICAL STATUS X'00' LINE DOWN/INACTIVE X'01' LINE HAS BEEN INACTIVATED X'02' LINE IS 'BUSY OUT' X'04' LINE IS BEING ACTIVATED X'08' LINE IS ACTIVE X'10' LINE IS BEING INACTIVATED LCB+28 TDT2 COMMAND BYTE BIT 0 = 1 BUSY LINE BIT 1 = 1 CLEAR LINE BIT 2 = 1 RESET LINE BIT 3 - 7 NOT USED LCB+5C # BUFFERS ALLOCATED TO THIS LINE LCB+5D DRIVER ERROR COUNTER LCB+5E NO BUFFER ERROR COUNTER LCB+5F FLOW CONTROL ERROR COUNTER LCB+60 PARITY ERROR COUNTER LCB+61 OVER-RUN ERROR COUNTER LCB+62 FRAMING ERROR COUNTER LCB+74 BREAK TIMER LCB+75 RING-OUT TIMER LCB+76 RING-OUT COUNTER DSP 3270 LCB SPECIFIC INFORMATION LCB+4F CURRENT NO. SYNC PAIRS INSERTIONS LCB+50 CURRENT NO. OF ERROR RETRIES LCB+51 CURRENT NO. OF NAK RETRIES LCB+52 CURRENT NO. OF ENQ RETRIES LCB+53 RECEIVE ACK COUNTER LCB+54 TRANSMIT ACK COUNTER LCB+55 CTS DROP-ERROR COUNTER LCB+56 DCD DROP-ERROR COUNTER LCB+5A CURRENT NO. WACK'S X780 LCB SPECIFIC INFORMATION LCB+4F CURRENT NO. OF SYNC PAIR INSERTIONS LCB+50 CURRENT NO. OF ERROR RETRIES LCB+51 CURRENT NO. OF NACK RETRIES LCB+52 CURRENT NO. OF ENQ RETRIES LCB+53 RECEIVE ACK COUNTER LCB+54 TRANSMIT ACK COUNTER LCB+55 CTS DROP-ERROR COUNTER LCB+56 DCD DROP-ERROR COUNTER COMMON DCB INFORMATION DCB+6 BITS 5-7 PACKET SEND SEQ. NO. P(S) DCB+7 BITS 5-7 PACKET REC. SEQ. NO. P(R) DCB+8 LCN # DCB+9 BITS 5-7 PACKET SEQ. NO. LAST CONFIRMED DCB+A BITS 5-7 PACKET SEQ. NO. LAST SENT TO NET DCB+B # PACKETS SENT DCB+D # PACKETS REC. DCB+F # RESETS SENT OR RECEIVED DCB+14 # BUFFERS IN HOLD QUEUE DCB+15 TIME VC WAS ESTABLISHED (SSMMHHDD) DCB+31 DESTINATION NETWORK ADDRESS THE FOLLOWING IS A DESCRIPTION OF THE TP3006 X.25 INTERFACE FROM THE SIO TO THE REAR PANEL CONNECTORS. SIO CHIP REAR PANEL CONNECTOR +--------------+ | | | DTRB |------------------->- DTR 20 | TXDB |------------------->- TXD 2 | RTSA |------------------->- LDL 13 | RTSB |------------------->- RTS 4 | DTRA |------------------->- LAL 19 | DCDA |---<-----------+--->- CTR 18 | | +---<- RLSD 8 | RXCA |--+ | RXCB |--+-------- ** ----<- RXC 17 | | +->- TXCE 24 | | ** --+->- RXCE 11 | TXCA |----+ | TXCB |----+------ ** ----<- TXC 15 | DCDB |----------- ** ----<- DSR 6 | CTSB |-------------------<- CTS 5 | RXDA |----+ | RXDB |----+--------------<- RXD 3 | CTSA |-------------------<- RI 22 | | +--------------+ < INBOUND SIGNAL > OUT BOUND SIGNAL IF DSR AND TXC, THEN USE EXTERNAL CLOCKING. IF DSR AND NO TXC, THEN USE INTERNAL CLOCKING DERIVED FROM THE CONFIGURED LINE SPEED PRODUCED FROM A CTC CHIP). IF THE CLOCKING IS PRODUCED INTERNALLY, THEN THE INTERNAL CLOCK IS ALSO PROVIDED ON PINS 11 AND 24 AT THE REAR PANEL. FOR THE TP3325, THE NETLINES ALWAYS USE THE EXTERNAL CLOCK SOURCE. THE HARDWARE WAS CHANGED DURING REFINEMENT OF THE MOD ONE XPB. IF THE ATTACHED DEVICE IS PROVIDING CLOCKING AND THE TP3025 IS PROVIDING CLOCKING, THE TP WILL DETECT THE CLOCKING AND WILL STOP CLOCKING. IN THE CASE OF THE TP3025 HAVING BEEN RESET AND LOADED, IF A TP3005/3006 IS THEN CONNECTED TO THE INTERFACE, THERE IS A RACE CONDITION WHERE THE DEVICE THAT PROVIDES THE CLOCKING IS ARBITRARY. THE HARDWARE LOGIC REQUIRES A RESET TO OCCUR FOR THE TP3025 TO CHANGE PRIOR SELECTION OF 1) INTERNAL/EXTERNAL CLOCKING AND 2) V35/RS232 INTERFACE AFTER A LOAD. THE DEBUG PORT "S" COMMAND WILL RETURN ONE HEX BYTE THAT REPRESENTS THE DATA SET SIGNALS STATUS AT THE SIO CHIP FOR THE DEFINED LINE (E.G. "S2" WILL RETURN THE DATA SET SIGNALS ON LINE 2). THE UPPER HALF OF THE BYTE IS USED TO REPRESENT THE DATA SET SIGNAL STATUS. BIT 7 6 5 4 3 2 1 0 | | | | ========== | | | | NOT USED | | | | DSR AT THE REAR ---+ | | +--- RTS AT THE REAR PANEL. DTR AT THE REAR -----+ +------ CTS AT THE REAR PANEL. THE FOLLOWING IS A DESCRIPTION OF THE DEVICE INTERFACE FOR THE SIO TO THE REAR PANEL. SIO CHIP REAR PANEL INTERFACE +--------------+ | | | RXD | ------------------------< 2 TD | TXD | ------------------------> 3 RD | DCD | -<-----------+----------< 4 RTS | | +----------> 5 CTS | DTR | ------------------------> 6 DSR | RTS | ------------------------> 8 DCD | RXC | -<--------- ** ---------< 11 | | PIO DSR -- ** ---------< 20 DTR | | -- ** ---------> 15 TC | | -- ** --------> 17 RC | TXC | -<--------- ** ---------< 24 TC | CTS | -<----------------------< 18 | | | | PIO -----------------< 25 | | PIO -----------------> 22 | | +--------------+ WITH DTR TRUE ( PIN 20), RXC (PIN 11) IS CHECKED FOR AN INBOUND CLOCK SIGNAL. IF THERE IS A CLOCK SIGNAL, THEN THE SIO IS CLOCKED EXTERNALLY FROM PIN 11 AND 24. IF THERE IS NO CLOCK ON PIN 11 THEN AN INTERNAL CLOCK SOURCE IS GATED TO THE SIO AND TO PIN 15 AND 17 ON THE REAR PANEL INTERFACE. THE OUTPUT OF THE DEBUG PORT 'S' COMMAND DISPLAYS ONE HEX BYTE THAT IS A COMPOSITE OF THE DATA SET SIGNALS FROM THE PIO AND SIO CHIPS. THE OUTPUT BIT DEFINITIONS ARE THE SAME AS THE X.25 LINE BUT A NOTE NEEDS TO MADE THAT THE X.25 IS A DTE INTERFACE AND THE DEVICE LINES ARE A DCE INTERFACE. THE UTILIZATION OF THE INBOUND RTS/CTS MAY NOT BE REQUIRED FOR THE TP TO MAINTAIN THE INTERFACE. PINS 22 AND 25 ARE PAD DEPENDANT SO THEY MAY BE USED FOR DIFFERENT FUNCTIONS THAN THOSE EXPECTED. ALL NUMERIC VALUES ARE IN HEX. COMMAND STRINGS CAN BE USED WHILE IN THE DEBUG PORT. ==============================================================< | XCB DIRECTORY TABLE (two bytes per entry) > | DEBUG |LOGGER| X.25 #0 | X.25 #1 | X.25 #2 | X.25 #3|....... L70,R24 | DCB | DCB | XCB | XCB | XCB | XCB | > |===============================================================> | | | | | | XCB#0 XCB#1 | XCB#2 XCB#3 | XCB#4 XCB#5 | | | | | | +->>---------------->>-+ | | +>>+ | | | | | | | | | +<<----------------<<-+ L76,R2 | | L7A,R2 | | | | | | L74,L,R80 | +<<---+ L78,L,R80 | | | | | +------------->>--------------> | +--------->>-------------> | | XCB >> > | | XCB >> > | +------------->>--------------> | +--------->>-------------> | | XCB+2D | | XCB+2D | | +>>+ | | +-<<---------------+ | +-<<-------------+ | | | | | | L(XCB+2D),L,R((MAX.LCN*3)+3) | | L(XCB+2D),L,R((MAX.LCN*3)+3) | | | | | +------------------>>--------> | +------------------>>--------> | | LCN VECTOR TABLE >> ABCCDD > | | LCN VECTOR TABLE >> ABCCDD > B |3 BYTES PER ENTRY >> ====== > B |3 BYTES PER ENTRY >> ====== > | +------------------>>--------> | +------------------>>--------> | | | | +--CC->> TRUNK LCNS -----> | +--CC->> CONCENTRATOR LCNS | | |LCN0 |LCN1 |... | | |LCN0 |LCN1 |... | | +--->>--+ | | | | THREE BYTE LCN ENTRY ==> AB CC DD | | = == == | | | | | | | XCB NUMBER ----+ | | | | LCN NUMBER ------+ +---- LCN TIMER | | | | | +-<<-----------------------------------------------------<<-------+ ** CC IS THE LCN NUMBER IN XCB B. B IN XCB #0 WILL POINT TO == = = XCB #4 IN THIS EXAMPLE. CC IN XCB #0 WILL GIVE THE LCN NUMBER USED IN == THE LCN VECTOR TABLES FOR XCB #4. 1) XCB OFFSETS DEFINITION XCB + 09 CONTROL DATA SET SIGNAL STATUS BIT 4 = 1 RTS HIGH 5 = 1 CTS HIGH 6 = 1 DTR HIGH 7 = 1 DSR HIGH THE S COMMAND RETRIEVES THIS LOC. XCB + 0B POINTER TO LINE CONFIGURATION RECORD. XCB + 0E NUMBER OF FRAMES DISCARDED. XCB + 0F NUMBER OF CRC ERRORS XCB + 10 NUMBER OF REJECTS SENT XCB + 11 NUMBER OF REJECTS RECEIVED XCB + 12 NUMBER OF T1 TIMEOUT XCB + 13 NUMBER OF COMMAND REJECTS SENT XCB + 14 NUMBER OF COMMAND REJECTS RECEIVED XCB + 15 NUMBER OF DISCONNECTS SENT XCB + 16 NUMBER OF DISCONNECTS RECEIVED XCB + 17 NUMBER OF SET MODE SENT XCB + 18 NUMBER OF SET MODE RECEIVED XCB + 19 NUMBER OF FRAME OVERFLOW XCB + 1A NUMBER OF I FRAMES SENT XCB + 1C NUMBER OF I FRAMES RECEIVED XCB + 24 FLAG BYTE BIT 0 = 1 DCE-TO-DTE FLOW INIT 1 = 1 DTE-TO-DCE FLOW INIT 2 = 1 LINK RESET (DISC. OR SETMODE SENT 3 = 1 DCE BUSY ( RNR SENT) 4 = 1 IN TIMER RECOVERY 5 = 1 SENT INTERNAL RESET. LAP RE-INIT. 6 = 1 SET POLL BIT IN NEXT FRAME. XCB + 27 LINE STATUS BIT 0 = 1 NOT ACTIVE 1 = 1 DEACTIVATED 2 = 1 BUSY-OUT 3 = 1 ACTIVATING 4 = 1 ACTIVE 5 = 1 DEACTIVATING XCB + 2B MAX. LCN PERMITTED XCB + 2C CURRENT NUMBER OF LCN IN USE XCB + 2D POINTER TO THE LCN VECTOR TABLE XCB + 47 'DISABLE/ ENABLE/ CLEAR COMMAND. NOT OPERATIONAL AT VERSION 1.01. 01 - BUSY 02 - CLEAR BUSY 04 - RESET LINE 2) LCN VECTOR TABLE. ( XCB + 2D ,L,A (LCN ADDRESS),R3) LCN ADDRESS = (LCN * 3) LCN + 0 BITS 0-3 - XCB DIRECTORY NUMBER. 4 - INIT CLEAR TIMER ON 5 - CLEAR INDICATION SENT 6 - CALL REQUEST SENT 7 - LCN ACTIVE LCN + 1 LCN NUMBER (SEE LCN + 0 , BITS 0-3 TO GET XCB NUMBER) LCN + 2 TIMER FOR LCN.