<REFERENCE>PRIME>DRB>ALL_ABOUT_BOOT
This information on the behavior of the boot process was drawn from various sources, including source for BOOT. It was collated by BORIS staff and Dennis Boone, 1987-2020.
BOOT [sense switch setting] [CPBoot_parms]
Common Sense Switches:
114 Ask for PDEV and PATHNAME
14114 Use Head 0 Drive 0 Controller 0 disk, boot to PRIMOS IV (PRIMOS)
10114 Use H0 D0 C0, boot to PRIMOS II (DOS)
4114 Ask for PDEV then boot to PRIMOS IV
11114 Use H0 D0 C0, ask for PATHNAME, boot to PRIMOS IV
114114 Use H0 D0 C0, skip PRIMOS.COMI, ask for CONFIG, boot to PRIMOS IV
CPBoot_parms:
2 Tells VCP you're using a rev 19 MAGSAV tape.
2000 Tells VCP to display debugging information while verifying
the CPU and controllers.
Valid boot devices sense switch settings are:
114 Drive 0, Controller 0 (Address '26)
314 Drive 1, Controller 0 (Address '26)
514 Drive 2, Controller 0 (Address '26)
714 Drive 3, Controller 0 (Address '26)
134 Drive 0, Controller 1 (Address '27)
334 Drive 1, Controller 1 (Address '27)
534 Drive 2, Controller 1 (Address '27) *
734 Drive 3, Controller 1 (Address '27) *
154 Drive 0, Controller 2 (Address '22)
354 Drive 1, Controller 2 (Address '22)
554 Drive 2, Controller 2 (Address '22) *
754 Drive 3, Controller 2 (Address '22) *
174 Drive 0, Controller 3 (Address '23)
374 Drive 1, Controller 3 (Address '23)
574 Drive 2, Controller 3 (Address '23) *
774 Drive 3, Controller 3 (Address '23) *
005 Tape unit 0, Controller 0 (Address '14)
205 Tape unit 1, Controller 0 (Address '14)
405 Tape unit 2, Controller 0 (Address '14)
605 Tape unit 3, Controller 0 (Address '14)
025 Tape unit 4, Controller 1 (Address '13) *
225 Tape unit 5, Controller 1 (Address '13) *
425 Tape unit 6, Controller 1 (Address '13) *
625 Tape unit 7, Controller 1 (Address '13) *
* On systems with a VCP3, only disk controllers 0 & 1 and tape
controller 0 are available with disks 2 & 3 or tape > 0, respectively.
Sense switch bits, decoded individually:
'100000 Ignores CONFIG file, Does NOT init. communication boards,
Prompts for PAGDEV, NTUSR.
Good for recovering from crashes, or changing CONFIG.
'040000 Not defined. (Enable R0DBG)
'020000 Not defined. (Break to R0DBG early in boot)
'010000 Get PRIMOS or DOS from device booted from. Prompts for
Physical Device Number and will accept a disk pdev or
MT<unit> (a tape drive number, 0 thru 7).
'004000 Do AUTOBOOT using the pathname from tha last successful boot.
'002000 Halts after restoring the program to be booted, but before
executing it. Good for T&M programs.
'001000 Prevents halts due to machine checks during boot.
Good for debugging hardware problems like bad memory.
'000400 Add 2 to disk unit number. (Units 2 & 3)
'000200 Add 1 to disk unit number. (Units 1 & 3)
'000100 Boot from some disk drive.
'000040 Halts immediatly to allow patching supervisor baud rate when
booting from magtape. See 20.0 Software Release manual.
'000020 Add 1 to controller number.
'000010 Use disk controller (not tape).
Decode of BOOT switch settings (from BOOT source)
* Switch(s) Meaning
* --------- -------
* '100000 Ignore config file and query user for COMDEV, PAGDEV, and
* NTUSR. (0 = assume valid config file). Used by Primos only.
*
* '060000 Allocated for use by the ring 0 debugger in Primos to specify
* that the ring 0 debugger will be used and whether to come up
* immediately in the debugger. Used by Primos only.
*
* '010000 Assume the program to be booted is on the same device that this
* boot was read from. (0 = query user for physical device number).
* Used by this boot program only.
*
* '004000 Assume we are booting Primos. Assume the path of the
* coldstart image PRIMOS.SAVE is the same as used in the last
* successful boot of Primos from the boot device. If
* MFD>BOOT_RUN_FILE_TREENAME does not exist or does not contain
* a valid treename, assume PRIRUN>PRIMOS.SAVE. If this does not
* exist, query the user for the treename.
* (0 = query user for treename to boot, which may or may not be
* Primos). Used by this boot program only.
*
* '002000 Halt immediately after loading the program to be booted, but
* before starting program execution to allow the operator to
* patch various locations in memory. The user just hits the
* start switch or enters "RUN" to start the program running.
* This option is possibly useful for running T&M's or debugging
* Primos. Note that after patching, the switches MUST be set
* back to their values at the start of the boot. If using a VCP,
* patch the switches register in the register file before entering
* the RUN command. (0 = execute the booted program without
* halting before hand.) Used by this boot program only.
*
* '001000 Don't run CPBOOT and this boot in machine check mode. This
* switch is used by CPBOOT only, only on VCP 4's (Mink) and up or
* updated VCP 3's (Weasel). 0 = the default on these machines
* which is to run in machine check mode. This switch has no
* effect on older machines and they always run this boot run in
* machine check mode.
*
* '000777 Boot device as follows: (select one only)
*
* '114 Disk drive 0, disk controller 0 (dev addr '26)
* '314 Disk drive 1, disk controller 0 (dev addr '26)
* '514 Disk drive 2, disk controller 0 (dev addr '26)
* '714 Disk drive 3, disk controller 0 (dev addr '26)
* '134 Disk drive 0, disk controller 1 (dev addr '27)
* '334 Disk drive 1, disk controller 1 (dev addr '27)
* '534 Disk drive 2, disk controller 1 (dev addr '27)
* '734 Disk drive 3, disk controller 1 (dev addr '27)
* '154 Disk drive 0, disk controller 2 (dev addr '22)
* '354 Disk drive 1, disk controller 2 (dev addr '22)
* '554 Disk drive 2, disk controller 2 (dev addr '22)
* '754 Disk drive 3, disk controller 2 (dev addr '22)
* '174 Disk drive 0, disk controller 3 (dev addr '23)
* '374 Disk drive 1, disk controller 3 (dev addr '23)
* '574 Disk drive 2, disk controller 3 (dev addr '23)
* '774 Disk drive 3, disk controller 3 (dev addr '23)
* '005 Tape drive 0, tape controller 0 (dev addr '14)
* '205 Tape drive 1, tape controller 0 (dev addr '14)
* '405 Tape drive 2, tape controller 0 (dev addr '14)
* '605 Tape drive 3, tape controller 0 (dev addr '14)
* '025 Tape drive 4, tape controller 1 (dev addr '13)
* '225 Tape drive 5, tape controller 1 (dev addr '13)
* '425 Tape drive 6, tape controller 1 (dev addr '13)
* '625 Tape drive 7, tape controller 1 (dev addr '13)
*
* Note: booting from disk controller 2 or 3 or from other than
* tape drive 0, controller 0 is available only on new machines.
* Older machines will also allow booting from other devices
* that have been de-supported as boot devices. (See the Notes
* section further on). These bits are used are used by CPBOOT,
* this boot, and possibly by booted programs.
*
* '000040 Halt immediately to allow patching the console baud rate.
* This boot defaults to 300 baud, but other console baud rates
* may be used by patching locations '1004 - '1006 as follows:
*
* Speed '1004 '1005 '1006
* ----- ----- ----- -----
* 110 baud 110 27 74006
* 300 baud 1010 76 34006
* 1200 baud 2010 373 34006
* 9600 baud 3410 3735 34006
*
* The user just hits the start switch or enters "RUN" to
* continue with the boot. Note that this option may be used
* ONLY when booting from tape. Also note that after patching,
* like the '002000 option above, the switches MUST be set back
* to their values at the start of the boot. If using a VCP,
* patch the switches register in the register file before entering
* the RUN command. (0 = execute the boot without halting).
* This bit is used only by this boot program.
* SWITCH SETTINGS: (from comments in BOOT source)
* 1-7 - FILE NUMBER, PROMPTS FOR TREENAME IF 0
* 8-9 - RELOCATION IN 16K'S IN 64K MACHINE
* 10 - 1 => SUPPRESS AUTOSTART OF LOADED PROGRAM
* 11 - 1 => WAIT FOR SOC/OPTION A CONTROL WORDS TO BE PATCHED
* 12 - 0 => 9-TRACK, 1 => 7-TRACK
* 13 - 1 => BOOTING A DOS IMAGE, 0 => BOOTING ANYTHING ELSE
* 14-16 - 101 (MAGTAPE BOOT)
HALT during BOOT addresses and LIGHTS
Halt at: Lights Description
1 XXXXXX UNACCEPTABLE STATUS FROM TAPE DRIVE
See tape error table for lights
503 000002 NO DATA RECORD AFTER TREENAME (also LIGHTS = '72642)
635 000001 LOAD COMPLETE, NO AUTOSTART (also halt at '175175)
440 000005 END LOGICAL TAPE ENCOUNTERED
641 000003 PROGRAM WON'T FIT IN MEMORY WITH BOOT
260 000021 WAITING FOR CONTROL WORDS TO BE PATCHED
Halt at: Lights Description
635 000001 LOAD COMPLETE, NO AUTOSTART (also halt at '175175)
503 000002 NO DATA RECORD AFTER TREENAME (also LIGHTS = '72642)
641 000003 PROGRAM WON'T FIT IN MEMORY WITH BOOT
440 000005 END LOGICAL TAPE ENCOUNTERED
260 000021 WAITING FOR CONTROL WORDS TO BE PATCHED
1 XXXXXX UNACCEPTABLE STATUS FROM TAPE DRIVE
See tape error table for lights
Disk Boot Errors
Octal Number
In Lights Error
100 Parity
101 Machine Check
102 PDEV number is not octal
103 Bad device type
104 Bad status (SMD, diskette)
105 Bad record ID, bad CRA
106 Incompatible boot records
Parity:
Check DSWSTAT
Bad device type:
If device type of 7 is entered.
Bad status:
Status word from SMD or diskette is stored in location '40.
Bad record ID:
Requested CRA is checked against the Record ID field of the
disk record header. Requested address is at location
'723-'724, actual address is at '760-'761.
Incompatible boot records:
First and second records of BOOT must come from same version.
Rev. 20 COMDEV replace:
CP> SYSCLR
CP> BOOT 5
Run File Treename= PRIRUN>PRIMOS.SAVE
OK, MTRESUME MT0 MAKE -DSK -DT -PART -BAUD [-FMT -NEWDSK -NO_INIT]
<make dialog>
OK, ADDISK 1060
OK, ATTACH MFD XXXXXX 0
OK, MTRESUME MT0 CMDNC0>{MAGRST.SAVE X.BEEPRST.SAVE}
<magrst dialog>
OK,
Rev. 19 COMDEV replace:
CP> SYSCLR
CP> BOOT 15
TREENAME= DOS>*DOS64
OK: <esc><esc>
CP> STOP
CP> SYSCLR
CP> BOOT 505
TREENAME= CMDNC0>MAKE
HALTED AT 072427: 000001
CP> {RUN BOOT} 170000
OK: S 1000 -DSK -DT -PART -BAUD [-FMT -NEWDSK -NO_INIT]
<make dialog>
OK: <esc><esc>
CP> STOP
CP> SYSCLR
CP> BOOT 505
TREENAME= CMDNC0>{MAGRST BEEPRST}
HALTED AT 154012: 003776
CP> {RUN BOOT} 177776
OK: STARTUP 1060
OK: ATTACH MFD XXXXXX 0
OK: S 1000
<magrst dialog>
OK:
Typical magtape boot sequence:
CP> {{BOOT 15}}
TREENAME={{*DOS64}}
PRIMOS II REV 19.1 11/22/82 (AT 170000)
OK: {{<ESC><ESC>}
CP> {{STOP}
HALTED AT 154012: 003776
CP> {{BOOT 505}}
TREENAME={{MAKE}}
HALTED AT 072427: 000001
CP> {{RUN 170000}}
OK: {{S 1000 -DISK <pdev> -PART <packname>}} ...
Other Notes
* When booted from disk, this boot is read in with the disk header at '760,
* the RVEC at '1000. When booted from tape, the boot is read in starting
* at location '200. The tape copy of this boot is therefore slightly re-
* arranged so the RVEC and starting code will be at '1000.
*
* In both cases, CPBOOT starts execution of the program at '1000 in 16S
* mode. Location '1000, which is the SA (starting address) of the RVEC,
* contains at JMP instruction to the start of the boot which immediately
* enters 64V mode and proceeds apace. Newer versions of CPBOOT start
* execution at the location contained in '1002, which is P (initial PC)
* of the RVEC, which also points to the start of the boot.
*
* Note: This boot is advertised as loading 256K images. In reality, the
* boot has to go somewhere, so while it will load starting at location 0/0
* if desired, it will not allow you to load in the last 5.5K of memory.
* 7. Load the run file from disk to memory location:
* The starting, ending locations and the register values can be
* found in the R-VEC. The R-VEC is supplied by LOAD for the T&Ms,
* and by MAPGEN for the coldstart image. These are 16-bit values,
* so the starting location and the PC register must be less than 64K.
* The R-VEC ending address is ignored by BOOT.SAVE and the run file
* is loaded until the end of file is reached.
*
* If the R-VEC is incorrect then the message:
* "INVALID R-VEC: SA: xxxxxx EA: xxxxxx PC: xxxxxx" will by printed
* and the system will then HALT. The R-VEC is considered invalid
* if the SA is greater than the EA or the initial PC is not between
* the SA and EA.
*
* If the program to be loaded will not overlay the boot, the program
* is read in "normally". If the program will overlay the boot, the
* portion that will overlay the boot is read into a buffer at the end
* of physical segment 3 (3/176000). After the load is completed or
* when loading has run into this buffer, a small program to copy the
* buffer to the proper place and start execution is also put up at the
* end of seg 3 and is executed to relocate the booted program back and
* start it. Note that this means that the last 5.5K of the possible
* 256K loaded by this booted actually cannot be written into. Execution
* of the loaded program is started via a LPSW using parameters from the
* booted program's RVEC. Note that at rev 20, DOS has been fixed so that
* it does not need to be special cased.
* 1. You can't reference a sector 0 location ('0 - '777) in a one word
* instruction in V-mode. This is because a single word reference to '0
* thru '377 implies a stack base meaning this is SB%+'0 thru SB%+'377.
* Similarly, a single word reference to '400 - '777 implies a link base
* meaning this is LB%+'400 thru LB%+'777. However since we zero out
* SB% and LB% to start, we make all our sector zero references relative
* to them and then everything works out peachy.
*
* 2. Historically, the switch settings understood by CPBOOT on boot are as
* follows:
*
* The switches comprise 16 bits labeled: -------UUSLCBXYZ,
* where: UU = unit number - 1
* S = storage module,
* L = lower platter (or head 2) of MHD,
* C = alternate controller,
* B = B prime (B') controller (4002 OR 4003),
* XYZ = 011 FHD, = 100 MHD, = 110 floppy disk.
*
* The only meaningful combinations and the derived physical disk
* numbers are:
* ------------0011 = B FHD -- OBSOLETE
* -----------C1011 = B' FHD -- OBSOLETE
* ----------L-0100 = B MHD -- OBSOLETE
* -------UU0LC1100 = B' MHD -- OBSOLETE
* -------UU1CC1100 = STORAGE MODULE ********** VALID
* -------------110 = FLOPPY -- OBSOLETE
*
* Those options labeled OBSOLETE were de-supported as boot
* devices at rev 20.0.
* 3. Physical device numbers (PDEV's) are encoded as follows:
*
* Given a 16-bit PDEV encoded as: D DDD NNN NCC TTT UUN
*
* The PDEV is interpreted as:
* D DDD = (Bits 1-4) Head displacement of partition / 2
* (for cartridge, must be zero)
* NNN N = (Bits 5-8) Number of heads in partition / 2
* (for cartridge, must be zero)
* CC = (Bit 9-10) Disk controller #.
* TTT = (Bits 11-13) Device type - see below.
* UU = (Bits 14-15) Physical drive number
* N = (Bit 16) = 1 if last partition has odd # heads
*
* The device type above (TTT) was decoded as:
* 0 = Option B MHD -- OBSOLETE
* 1 = Option B FHD -- OBSOLETE
* 2 = Floppy disk -- OBSOLETE
* 3 = Option B' MHD, 8 sector -- OBSOLETE
* 4 = Option B' FHD -- OBSOLETE
* 5 = Option B' MHD, 32 sector -- OBSOLETE
* 6 = Storage module ************************* VALID
* >6 = ERROR
*
*
* 4. Historically, before this boot was rewritten at rev 20.0, the
* meaning of the control panel switches to DKBOOT was as follows:
*
* RRRAP--UUSLCBXYZ,
*
* DKBOOT was pretty much limited to booting up DOS and Primos.
*
* RRR = Relocation amount and therefore which version of DOS
* to use: *DOS16, *DOS24, *DOS32, or *DOS64.
*
* A = Assume device and partition DKBOOT was booted from will
* contain the version of DOS to be booted. 0 = query for
* physical device. The meaning of this bit has been
* retained.
*
* P = Automatically boot up Primos. The meaning of this bit
* has been retained after a fashion. Under the old DKBOOT,
* if this bit were zero, we would only boot DOS and not go
* on to boot Primos. Now we ask for the treename of the
* file to boot.
*
* UUSLCBXTZ = See the definition under item 2 above.
*
*
* 5. Historically, before this boot was rewritten at rev 20.0, the
* meaning of the control panel switches to MTBOOT was as follows:
*
* Bits Meaning
* ---- -------
* 1-7 File number, prompts for treename if 0.
* 8-9 Relocation in 16K's in 64K machine.
* 10 1 => Suppress autostart of loaded program.
* 11 1 => Halt for SOC/Option A control words to be patched.
* 12 0 => 9-track tape, 1 => 7-track tape.
* 13 1 => Booting a DOS image, 0 => booting anything else.
* 14-16 101 (Magtape boot).
* /BTDATA/ - The following comprises a common area to be referenced by
* anything that gets booted, assuming that the program booted does
* not overlay this area. In particular, Primos (SEG14.PMA) and DOS
* make use of this information. Do not get this out of order.
*
BTDATA EQU *
DVNO BSS 1 LOGICAL DEVICE NUMBER (PDEV) *** MUST BE @ '100 ***
MTDEV BSS 1 TAPE DRIVE # *** MUST BE @ '101 ***
SWTCHS BSS 1 FRONT PANEL SWITCHES ON BOOT *** MUST BE @ '102 ***
TRNMPT BSS 2 PTR TO BOOT FILE TREENAME *** MUST BE @ '103 ***
ASRSPD BSS 1 ASR SOC CONTROL WORD *** MUST BE @ '105 ***
SERPTR BSS 2 PTR TO SERIALIZATION DATA *** MUST BE @ '105 ***
* DISK record 0 (DKBOOT) is loaded by CPBOOT with the 16 word disk header
* @ '760 and the actual record starting at '1000. Since MFD>BOOT is a .SAVE
* file, the first 9 words ('1000 - '1010) are actually an RVEC.
*
* TAPE record 0 (MTBOOT) is loaded by CPBOOT @ '200. The boot is
* re-arranged so that the RVEC and following code that is supposed to be
* at '1000 is at '1000. The tape boot specific code will immediately
* relocate the code back where it belongs.
* Older versions of CPBOOT JST to location '777 (SA in R-VEC) in
* 16S mode which contains an S-mode jump to BOOT. (Note that if we
* execute this JMP in other than 16S mode, it is a JMP to BOOT+1,
* hence we have two E64V instructions in a row @ BOOT).
*
* Newer versions of CPBOOT jump to the location pointed to by '1002
* (the P-reg in the R-VEC).
*
* Note: A SYSCLR followed by a RUN will will always set us back to
* running at '1000 in S-mode.
* If RAT header length is greater than eight, set NPERTK (# sectors per
* track) from RAT, else set to default of 9.
* Some of the following errors just halt at first as the code to print
* messages isn't in the first record of the disk boot, but when it is
* read in, these pointers will change to routines that will print a user
* friendly message.
*
* If the system does halt, the number following the halt is displayed
* in the lights on a front panel or printed following the halt address
* in the following halts. Note that they are distiguished from any
* other halt (which would be a bug) by the number in the lights being
* in the 100's.
*
ER106 HLT PAGES OF BOOT NOT CONSISTENT, ONE FROM ONE REV.
OCT 106 ONE FROM ANOTHER (CHECK UNIT SWITCHES 8,9)
*
ER104 DAC *+1 (THIS LATER GETS CHANGED TO A PTR. TO ERR104)
STA SB%+'40 SAVE STATUS CODE IN '40
HLT
OCT 104 DISK STATUS ERROR, CODE IN '40
*
ER105 DAC *+1 (THIS LATER GETS CHANGED TO A PTR. TO ERR105)
HLT
OCT 105 BAD ID, REQUESTED AND FOUND DON'T MATCH
* The first record is read into a BUFF in seg 0. We then
* examine the RVEC to determine if the run file would overlay
* the boot at all. If not, the contents of BUFF are moved to
* place and we continue to read to the proper place in memory.
*
* If the run file will overlay the boot, we move the contents
* of BUFF to another buffer at 3/167000 and continue reading
* up there. Once the effective load point has passed the end
* of the boot, we stop reading into the buffer and read directly
* to the correct address in memory. We continue reading until EOF
* is reached or we load within 1024 words of our buffer
* at 3/167000.
*
* At this point, the buffer is moved down to 3/166000,
* and the treename of the file read is copied to
* 3/177600 - 3/177777 as a char fixed (128).
* We then jump to a program we've copied to 3/177000
* which will move the contents of the buffer at 3/166000
* to place on top of this boot program and then starts
* the program read using values from the R-vec.
CPBOOT loads MTBOOT at '200.
Addendum to the above info on bits 14-16 of the sense switches,
from MAN1671 (July 1975). Additional info, including early
source code for blinkenlights control panel automatic program
load bootstraps, appears in LDS2886.
These sense switch patterns originate in automatic program loader
options which could be installed into the control panels on early
CPUs (100/200/300).
0 0 0 Start at '1000
0 0 1 Boot from ASR (i.e. low speed tape reader on ASR33)
0 1 0 Boot from high speed tape reader