* *------------------------------------------------------------------------------------------------- * Internal Binary Loader (IBL) for HP 5420A and 5423A Signal Analyzers *------------------------------------------------------------------------------------------------- * * Filename: IBLROM.asm * Project Name: HP 5420A/5423A Restoration Project * Project Purpose: Restoration to full operation the HP 5420A Digital Signal * Analyzer and the HP 5423A Digital Structural Analyzer. * * Target CPU: HP 21MX * Date: 6 Jan 2013 * Verson: 1.0.1 * Author: Peter D O'Neill * Source: Disassembled from ROMs in a 5420A * * File Purpose: This file is to initiate the system boot process, it performs * a checksum on itself, then resets enough of the system * hardware so as to allow operation of keys, LEDs, and the * tape drives. This first operation is the Light test #1. * Next the cartridge drives look for the presence of a tape. * When a tape is found it is read and the sofware looks for * a specific record type which indicates that it is the MGEN * software. Once sucessfully loaded the IBL hands over * program control to MGEN. * *------------------------------------------------------------------------------------------------- * Register Equates *------------------------------------------------------------------------------------------------- * A EQU 0 ; A-register equate B EQU 1 ; B-register equate * *------------------------------------------------------------------------------------------------- * Equates for MIOB *------------------------------------------------------------------------------------------------- * MIOB.SELECT EQU 10B ; I/O Select address for MIOB KEYBOARD.DEVICE EQU 20000B ; 0010 5443A Kyboard/Control -- Keyboard TAPE.DEVICE EQU 30000B ; 0011 5441A Display -- A9 Cartridge Interface * *------------------------------------------------------------------------------------------------- * Equates for LIGHT/KEY control bits *------------------------------------------------------------------------------------------------- * REMOTE.LIGHT EQU 000056B ; Select REMOTE light (default state is OFF) INPUT.LIGHT EQU 000057B ; Select INPUT light (default state is OFF) VIEW.LIGHT EQU 000060B ; Select View light (default state is OFF) KBD.ENABLE EQU 000067B ; Keyboard enable ON EQU 000100B ; Light ON flag GOLD.KEY EQU 000072B ; KEY.ON.5441A EQU 000100B ; Key is on 5441A FIRST.PRESS EQU 000200B ; First key press * *------------------------------------------------------------------------------------------------- * Equates for TAPE CARTRIDGE control bits *------------------------------------------------------------------------------------------------- * FRONT EQU 001000B ; Front cartridge on SELECT EQU 006000B ; Cartride select code READ EQU 002000B ; Read from tape control bit RUN EQU 000100B ; Run tape control bit LITE EQU 000040B ; Cartridge activity light * ORG 100B * *------------------------------------------------------------------------------------------------- * Initialise System *------------------------------------------------------------------------------------------------- * LOADER.START CLC 0B,C ; Clear all I/O devices Z000101 CLA,CLE ; Clear A and E reg prior to forming a checksum * ; of the IBL, the contents of this location are * ; also used as mask data in other parts of the code * *------------------------------------------------------------------------------------------------- * * Perform a checksum of the IBL program * * Location 000233 initially contains 000100 and (SEND.MIOB.CW) is 177500 * These two locations are normally storage for subroutine return addresses * so they can be used as temporary storage. 000233 containds the address * pointer to the locations being summed and 000256 contains the counter * which when at increment 300B is zero so the checksum will stop. * *------------------------------------------------------------------------------------------------- * GEN.CHECKSUM ADA READ.FROM.TAPE,I ; Add contents of memory to A-reg ISZ READ.FROM.TAPE ; increment the memory address ISZ SEND.MIOB.CW ; increment the word counter JMP GEN.CHECKSUM ; if we are not done then continue to make checksum INA,SZA ; increment the final data, if zero IBL is ok COUNT.01 HLT 10B,C * *------------------------------------------------------------------------------------------------- * Here if the IBL Checksum verified, Now perform a light test *------------------------------------------------------------------------------------------------- * LIGHT.TEST LDA COUNT.01 ; Use the above halt code as count data STA A.COUNTER ; save it to the (A.COUNTER) to be used in LONG.DELAY LDA Z000254 ; Start of light test with control word 044000 * ; though to 077777 then from 000000 to 027600 LIGHT.TEST.1 JSB SEND.MIOB.CW ; Send an MIOB Control Word INA ; increment CPA Z000325 ; 027600 should be in the (Z000325) * ; Note Page 9-35 of manual says "The final control * ; word sent (027600) causes the keyboard to generate * ; a master PUP (MPUP) to all MIOB devices, restarting * ; all MIOB operations" but 027600 isn't sent but * ; 027577 is. However, according to the KPUP (Bit 9) * ; and the MPUP (Bit 7) definitions both KPUP and MPUP * ; should have been triggered before a count of 027577 RSS ; skip if A-reg = (Z000325) JMP LIGHT.TEST.1 * *------------------------------------------------------------------------------------------------- * Turn on the Keyboard so operator can restart the tape read *------------------------------------------------------------------------------------------------- * LDA KEYBOARD.ENABLE ; Enable the keyboard JSB SEND.MIOB.CW ; Send an MIOB Control Word * *------------------------------------------------------------------------------------------------- * Check if the front panel is connected, and if so reverse the order of * tape drive cartridge searching, normall rear then front. If the front * panel is found the order changes to front then rear. *------------------------------------------------------------------------------------------------- * LIB 1B ; is the special front panel plugged in? * ; if it is not plugged data will be 177777 ISZ B ; if the result here is 0 then skip for normal operation JMP FRONT.DRIVE ; with front panel connected start with front cartridge drive * *------------------------------------------------------------------------------------------------- * Select Tape Drive (Initially select bits are set for Front Tape Drive) * so if front panel is not plugged in we start with internal cartridge * Each time we return here we change drive selection from Front to internal * or internal to front. *------------------------------------------------------------------------------------------------- * OTHER.DRIVE LDA SELECT.TAPE ; Get the tape select bits XOR DRIVE.MASK ; Flip the bits to select the other tape drive STA SELECT.TAPE ; save the result * FRONT.DRIVE JSB SELECT.A.CART ; Select the cartridge drive JSB LONG.DELAY LDA TAPE.STOPPED ; Place tape in read mode, tape motion stopped JSB SEND.MIOB.CW ; Send an MIOB Control Word JSB READ.FROM.TAPE LDA RUN.TAPE ; Start tape running JSB SEND.MIOB.CW ; Send an MIOB Control Word * *------------------------------------------------------------------------------------------------- * Start looking for an Inter Record Gap (IRG) *------------------------------------------------------------------------------------------------- * GET.IRG LDA VIEW.OFF ; Turn off the VIEW light JSB SEND.CW.TEST * GET.IRG.1 JSB READ.FROM.TAPE ; IRG, Waiting for inter-record gap or is cart in drive? LDA CODE.WORD.STORE ; return the code word AND Z000101 ; mask off all but IRG, ERROR, and MVG bits CPA IRG.ERROR ; compare with IRG and ERROR RSS ; Reverse skip sense JMP GET.IRG.1 ; loop if not equal LDA REMOTE.OFF ; Turn off the REMOTE light JSB SEND.CW.TEST * *------------------------------------------------------------------------------------------------- * * Here we are waiting for status from the tape indicating that the IRG * has finished, and the new data word from the tape should be the first * word of the record header for MGEN. Based on the operation of the following * code the struction of the MGEN record appears to be: * * Header: * * Word #1 MGEN identifier, -257 or 177377B * Word #2 Absolute start address (masked to below 16k boundary) * Word #3 Count of words to load * Word #4 Checksum of header * * Data: * * 1st Word First data word * | * nth Word Nth data word * Checksum of data * *------------------------------------------------------------------------------------------------- * IRG.LOOP JSB READ.FROM.TAPE ; Cart is on, found IRG, waiting for end of IRG LDA CODE.WORD.STORE ; return a code word AND IRG.MASK ; mask off all but IRG and DATA bits SZA ; Skip if IRG has finished JMP IRG.LOOP ; loop otherwise LDA REMOTE.ON ; Turn on the REMOTE light JSB SEND.CW.TEST LDB TAPE.DATA ; Get the Record identification STB RECORD.ID ; Save it RECORD.ID JSB READ.FROM.TAPE ; get the block start address (second header word from tape) AND MASK.16K ; mask the address to ensure it is below the 16k boundary STA MGEN.POINTER ; save to the address pointer location STA MGEN.XFR ; save the start address to the MGEN transfer storage location JSB READ.FROM.TAPE ; Get third header word from tape CMA,INA ; complement A-reg and inc by one -- 2's complement IOR MINUS.4K ; Or the result with 170000 STA RECORD.COUNT ; and save it STB CHECKSUM ; save the checksum from B-reg JSB READ.FROM.TAPE ; read the header checksum CPA CHECKSUM ; do we have a checksum match? RSS ; skip next instruction if the checksum was okay JMP GET.IRG ; otherwise loop back and start looking for the next IRG LDA VIEW.ON ; Turn on the view light, Unloaded was 100100 JSB SEND.CW.TEST LDA MGEN.POINTER ; get the MGEN pointer/start address AND MINUS.1K ; mask of all but the important part of the address SZA,RSS ; test if the result is zero, if not then skip JMP GET.IRG ; else, it wasn't correct for MGEN, go look for next IRG * READ.RECORD JSB READ.FROM.TAPE ; Read a word from the tape STA MGEN.POINTER,I ; save it to memory CPA MGEN.POINTER,I ; read it back and do they match? RSS ; Yes, then skip JMP WAIT.FOR.KEY.3 ; no match, indicate there is a memory error LDA CODE.WORD.STORE AND Z000101 SZA JMP GET.IRG ISZ MGEN.POINTER ; increment the memory pointer and skip if zero MASK.16K ABS 037777B ; This is a tricky multi-use, this code is an ISZ * ; for location 001777 in the current page which * ; happens to be page zero. Also the code is used * ; a mask for for the MGEN pointer address. * ; This increments the word count and exits reading * ; the tape when all words are read. JMP READ.RECORD ; Loop if not all words have been read STB CHECKSUM ; save the calculated checksum JSB READ.FROM.TAPE ; read the checksum word from tape CPA CHECKSUM ; Do the checksums match? IRG.MASK RSS JMP GET.IRG ; No, then go and look for the next IRG LDA SELECT.TAPE LDB RECORD.ID ; Get the off tape record identification CPB MGEN.ID ; was it an MGEN recird? JMP MGEN.XFR,I ; Yes, Then transfer control to MGEN JMP GET.IRG ; No, then go and look for the next IRG * *------------------------------------------------------------------------------------------------- * Subroutine, Read a word from the tape with error handling * If the data was without error then it is returned in A-reg * as well as being stored to TAPE.DATA, B-reg returns the current * value of the checksum. *------------------------------------------------------------------------------------------------- * READ.FROM.TAPE ABS 100B ; Initially 100B, used as the address pointer * ; for the Checksum test routine CLC MIOB.SELECT ; set to data mode? JSB GET.CODE.WORD ; Get a code word from the MIOB STA CODE.WORD.STORE ; Save the returned code word IOR TAPE.MASK ; OR A-reg with TAPE MIOB Address CPA CODE.WORD.STORE ; Compare the result with code word RSS ; and skip next if we don't have a match JMP WAIT.FOR.KEY ; Here if the code word was not from the tape interface RAR,RAR ; shift the COUT bit to bit 0 SLA,RAR ; if the cartridge in the drive skip next instruction JMP OTHER.DRIVE ; If here, toggle the drive selection to the other drive RAR,SLA,RAR ; Skip next instruction if EOT was not found, shift to MERR+EOT JMP HANDLE.EOT ; If here, go and manage the EOT condition FORWARD.REVERSE SLA ; if MERR+EOT bit not set then skip next instruction JMP WAIT.FOR.KEY.2 ; if here then we have a motor error, indicate major fault JSB GET.CODE.WORD ; Get data from the tape STA TAPE.DATA ; Save the data in temporary storage Z000254 ADB A ; Add new data to the checksum in B-reg JMP READ.FROM.TAPE,I ; Return to caller * *------------------------------------------------------------------------------------------------- * Subroutine, Send MIOB Control Word, on entry control word is in A-reg *------------------------------------------------------------------------------------------------- * SEND.MIOB.CW ABS 177500B ; initially was 177500, used as checksum counter STA CONTROL.WORD ; Save the control word to be sent CLC MIOB.SELECT,C ; Set DATA Mode SFC MIOB.SELECT ; Switch MIOB to Control Mode DRIVE.MASK ALR,ARS ; No MIOB addresses above 3 (don't know how 7 is addressed) OTA MIOB.SELECT ; Send the command STC MIOB.SELECT,C ; Issue a COMMC JMP SEND.MIOB.CW,I ; Return to caller * *------------------------------------------------------------------------------------------------- * Handle End Of Tape *------------------------------------------------------------------------------------------------- * HANDLE.EOT JSB LONG.DELAY JSB SELECT.A.CART LDB MGEN.ID LDA RUN.TAPE ; Get the tape run control word XOR FORWARD.REVERSE ; Flip the Forward/Reverse bit STA RUN.TAPE ; Save the tape run control word * HANDLE.EOT.1 JSB SEND.MIOB.CW ; Send an MIOB Control Word to reverse the tape direction ISZ B JMP HANDLE.EOT.1 JMP WAIT.FOR.KEY.2 ; Unloaded was 100100 * ABS 105577B ; Special IBL Load instruction used in 5420 and 5423A * *------------------------------------------------------------------------------------------------- * Subroutine to get a code word, and or data from a tape *------------------------------------------------------------------------------------------------- * GET.CODE.WORD ABS 024100B ; Initially 024100 or JMP 100B, saves return address STC MIOB.SELECT,C ; Set Control bit of I/O Channel 10B IRG.ERROR CLA ; Set up the loop counter for 65k * ; This is also used as a mask for IRG and ERROR bits WAIT.FOR.DATA INA,SZA,RSS ; increment counter and skip next instruction till A reg = 0 JMP WAIT.FOR.KEY ; Here if we lost data, handle lost data SFS MIOB.SELECT ; Skip next instruction MIOB flag set, device ready JMP WAIT.FOR.DATA ; loop and increment the counter LIA MIOB.SELECT ; Read a word from the MIOB JMP GET.CODE.WORD,I ; Return to caller * *------------------------------------------------------------------------------------------------- * LONG DELAY Subroutine, Timing dependent on locations B.COUNTER and A.COUNTER *------------------------------------------------------------------------------------------------- * LONG.DELAY ABS 150570B ; Initially was 150570, saves return address LDA A.COUNTER ; Initialize the A-reg count LONG.DELAY.1 LDB B.COUNTER ; Initialize the B-reg count LONG.DELAY.2 ISZ B ; Increment B-reg counter, and skip if zero JMP LONG.DELAY.2 ISZ A ; Increment A-reg counter, and skip if done JMP LONG.DELAY.1 JMP LONG.DELAY,I ; Return to caller * *------------------------------------------------------------------------------------------------- * Data storage MIOB control words and count values *------------------------------------------------------------------------------------------------- * SELECT.TAPE ABS TAPE.DEVICE+SELECT+FRONT+LITE TAPE.STOPPED ABS TAPE.DEVICE+READ RUN.TAPE ABS TAPE.DEVICE+READ+RUN+LITE Z000325 ABS 027600B REMOTE.ON ABS KEYBOARD.DEVICE+REMOTE.LIGHT+ON REMOTE.OFF ABS KEYBOARD.DEVICE+REMOTE.LIGHT VIEW.ON ABS KEYBOARD.DEVICE+VIEW.LIGHT+ON VIEW.OFF ABS KEYBOARD.DEVICE+VIEW.LIGHT INPUT.ON ABS KEYBOARD.DEVICE+INPUT.LIGHT+ON INPUT.OFF ABS KEYBOARD.DEVICE+INPUT.LIGHT KEYBOARD.ENABLE ABS KEYBOARD.DEVICE+KBD.ENABLE+ON GOLD.PRESSED ABS KEYBOARD.DEVICE+GOLD.KEY+KEY.ON.5441A+FIRST.PRESS MINUS.4K ABS -4096 MINUS.1K ABS -1024 B.COUNTER ABS -5B TAPE.MASK ABS TAPE.DEVICE MGEN.ID ABS -257 * *------------------------------------------------------------------------------------------------- * SELECT A TAPE CARTRIDE DRIVE *------------------------------------------------------------------------------------------------- * SELECT.A.CART NOP ; saves return address LDA SELECT.TAPE ; get the Cartridge select control word JSB SEND.MIOB.CW ; Send an MIOB Control Word JMP SELECT.A.CART,I ; Return to caller * *------------------------------------------------------------------------------------------------- * Subroutine Send a Control Word and test for MIOB fault *------------------------------------------------------------------------------------------------- * SEND.CW.TEST NOP ; saves return address JSB SEND.MIOB.CW ; Send an MIOB Control Word SFS MIOB.SELECT ; was the FLAG set? JMP WAIT.FOR.KEY ; no LIA MIOB.SELECT ; yes, read the returned word CPA CONTROL.WORD ; was it the same as was control word we sent? JMP SEND.CW.TEST,I ; if we have a match then return to caller * *------------------------------------------------------------------------------------------------- * Wait for the GOLD/Shift key, Flash INPUT/ALPHA light while waiting * WAIT.FOR.KEY.3, Memory failure test, light flashes 12 times/sec * WAIT.FOR.KEY, MIOB failure, light flashes 3 times/sec * WAIT.FOR.KEY.2, EOT or MOTOR SERVO ERROR, light flashes once every 2sec *------------------------------------------------------------------------------------------------- * WAIT.FOR.KEY LDB MINUS.4K ; Get a count of 4096 WAIT.FOR.KEY.1 STB A.COUNTER ; save it to A.COUNTER for LONG.DELAY WAIT.FOR.KEY.2 LDA INPUT.OFF ; Turn off INPUT/ALPHA light JSB SEND.MIOB.CW ; Send the MIOB Control Word CLC MIOB.SELECT STC MIOB.SELECT,C JSB LONG.DELAY LIB MIOB.SELECT ; Read the Code Word from the MIOB CPB GOLD.PRESSED ; Was the GOLD (5420A) or SHIFT (5423A) key pressed? JMP LIGHT.TEST ; Yes, then Restart the Boot process at the light test JSB SELECT.A.CART LDA INPUT.ON ; Turn on INPUT/ALPHA light JSB SEND.MIOB.CW ; Send the MIOB Control Word JSB LONG.DELAY JMP WAIT.FOR.KEY.2 * WAIT.FOR.KEY.3 LDB MINUS.1K ; count of 1024. fastest flash rate for memory error JMP WAIT.FOR.KEY.1 * NOP ; Unloaded was 100100 CLC 0B,C MGEN.POINTER CLA,RSS * MGEN.XFR ABS 063756B RECORD.ID ABS 006700B TAPE.DATA ABS 017742B CODE.WORD.STORE ABS 007306B CONTROL.WORD ABS 027713B ; MIOB Control Word storage CHECKSUM ABS 002006B A.COUNTER ABS 027703B ABS 102077B ABS 027700B ABS 077754B ABS 017742B ABS 017742B ABS 074000B ABS 077755B ; 037755B ABS 067755B ABS 047777B ABS 002040B ABS 027740B ABS 017742B ABS 040001B ABS 177755B ABS 037755B ABS 000040B ABS 037754B ABS 027720B ABS 017742B ABS 054000B ABS 027702B ABS 102011B ABS 027700B ABS 102055B ABS 027700B * *------------------------------------------------------------------------------------------------- * This looks like a subroutine that is relocated and or gets used by MGEN * (12/2/2015) from what I know now this isn't used by MGEN *------------------------------------------------------------------------------------------------- * NOP CLB,CME STC MIOB.SELECT,C SFS MIOB.SELECT ABS 027745B MIB MIOB.SELECT SEZ,RSS ABS 127742B BLF,CLE,BLF ABS 027744B * NOP NOP ABS 177765B NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP ORG 1777B RECORD.COUNT BSS 1 * END