/               MINIMAL PDP-8 BOOTSTRAP PROGRAM (RX)                Page 1


    1              /               MINIMAL PDP-8 BOOTSTRAP PROGRAM (RX)
    2              /
    3              / Taken from a manual for an 8/e disk subsystem built by DSD;
    4              / shorter and easier to toggle in than DECs bootstrap.
    5              
    6              / The following is a minimal length boot program for both
    7              / the RX01 and RX02.  This boot tries only the specified
    8              / drive with the specified density.  Start at location 32 to
    9              / BOOT drive 0.  Start at location 22 to boot drive 1.
   10              / This has been verified to work with an OS/8 diskette.
   11              
   12              / the contents of locations 60 and 61 can be fudged to
   13              / change what disk and what density are used.
   14              
   15              / configuration section
   16              
   17        0750  IOTADR=0750             / default system drive is at IOT 75
   18              
   19        0000  DRIVE0=0000
   20        0020  DRIVE1=0020
   21        0000  DRIVE=DRIVE0            / set to either DRIVE0 or DRIVE1
   22              
   23        0000  SINGLE=0000
   24        0400  DOUBLE=0400
   25        0000  DENSTY=SINGLE           / set to either SINGLE or DOUBLE
   26              
   27              / RX01 and other opcode definitions
   28              
   29        6751  LCD=6001+IOTADR
   30        6752  XDR=6002+IOTADR
   31        6753  STR=6003+IOTADR
   32        6755  SDN=6005+IOTADR
   33              
   34        7301  NL001=CLA CLL IAC
   35        7305  NL002=CLA CLL IAC RAL
   36        7327  NL006=CLA CLL CML IAC RTL
   37              
   38              / THIS SECTION IS NEEDED ONLY WHEN BOOTING FROM DRIVE 1.
   39              / READS IN SECTOR 1 TRACK 1 ON DRIVE O OR 1.
   40              
   41              / DOES NOT USE LOCATIONS 22-31 WHEN STARTED AT 32
   42              
   43              / START HERE TO BOOT DRIVE 0 (ASSUME MASTER CLEAR HAS
   44              / READ DRIVE 0 TRACK 1 SECTOR 1 FOR YOU).
   45              
   46        0032  *32
   47 00032  7305  BOTDV0, NL002           / MAKE EMPTY BUFFER COMMAND
   48 00033  6755  CHKFLG, SDN             / WAIT FOR DONE FLAG UP
   49 00034  5054          JMP     LOAD+1  / NO - CHECK FOR READY TRANSFER
   50 00035  1061          TAD     UNIT    / YES-PUT IN READ UNIT, DENSITY



      /               MINIMAL PDP-8 BOOTSTRAP PROGRAM (RX)                Page 2


   51 00036  6751          LCD             / SEND EMPTY BUFFER COMMAND
   52 00037  5047          JMP     BOTLP   / START TO LOAD SECTOR BUFFER
   53              
   54        0047  *47     /////////////////
   55              
   56 00047  4053  BOTLP,  JMS     LOAD    / READ NEXT WORD FROM SILO
   57 00050  3002          DCA     2       / START LOADING AT LOC. 2
   58 00051  2050          ISZ     .-1     / BUMP LOAD ADDRESS
   59 00052  5047          JMP     BOTLP   / CONTINUE EMPTYING BUFFER
   60              /
   61 00053  0000  LOAD,   .-.             / DATA TRANSFER SUBROUTINE
   62 00054  6753          STR             / SKIP IF CONTROLLER WILL SPEAK
   63 00055  5033          JMP     CHKFLG  / NO - CHECK IF FINISHED
   64 00056  6752          XDR             / TRANSFER DATA IN OR OUT
   65 00057  5453          JMP I   LOAD    / RETURN TO CALLER
   66              /
   67 00060  7004          7004+DRIVE      / USED BY SECONDARY BOOT
   68                                      / TO SELECT DRIVE 0 OR DRIVE 1
   69 00061  0000  UNIT,   DENSTY+DRIVE    / WHAT TRANSPORT, WHAT DENSITY?
   70              $

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