| 1 | .tr | |
| 2 | .th "BOOT PROCEDURES" VIII 11/1/73 |
| 3 | .sh NAME |
| 4 | boot procedures \*- UNIX startup |
| 5 | .sh DESCRIPTION |
| 6 | The advent of the new system has |
| 7 | changed the boot procedures. |
| 8 | .it "These procedures apply only to C-language systems." |
| 9 | .s3 |
| 10 | .it "How to start UNIX.||" |
| 11 | UNIX is started by placing it in core |
| 12 | starting at location zero and transferring to zero. |
| 13 | There are various ways to do this. |
| 14 | If |
| 15 | UNIX is still intact after it has been running, |
| 16 | the most obvious method is |
| 17 | simply to transfer to zero. |
| 18 | .s3 |
| 19 | The |
| 20 | .it tp |
| 21 | command places a bootstrap program |
| 22 | on the |
| 23 | otherwise unused block zero of the tape. |
| 24 | The DECtape version of this program is |
| 25 | called |
| 26 | .it tboot, |
| 27 | the magtape version |
| 28 | .it mboot. |
| 29 | If |
| 30 | .it tboot |
| 31 | or |
| 32 | .it mboot |
| 33 | is read into location zero and |
| 34 | executed there, |
| 35 | it will type `=' on the console, |
| 36 | read in a |
| 37 | .it tp |
| 38 | entry name, |
| 39 | load that entry into core, |
| 40 | and transfer to zero. |
| 41 | Thus the next easiest way to run UNIX |
| 42 | is to maintain the UNIX code on a tape using |
| 43 | .it tp. |
| 44 | Then when a boot is required, |
| 45 | execute (somehow) a program |
| 46 | which reads in and jumps to |
| 47 | the first block of the tape. |
| 48 | In response to the `=' |
| 49 | prompt, |
| 50 | type the entry name of the system on the tape |
| 51 | (we use plain `unix'). |
| 52 | It is strongly recommended that a current version of |
| 53 | the system be maintained in this way, |
| 54 | even if the first or third methods of booting the |
| 55 | system are usually used. |
| 56 | .s3 |
| 57 | The standard |
| 58 | DEC ROM which loads DECtape is sufficient to |
| 59 | read in |
| 60 | .it tboot, |
| 61 | but the |
| 62 | magtape ROM loads block one, not zero. |
| 63 | If no suitable ROM is available, |
| 64 | magtape and DECtape programs are presented below which may be |
| 65 | manually placed in core and executed. |
| 66 | .s3 |
| 67 | A third method of rebooting the system involves the otherwise unused |
| 68 | block zero of each UNIX file system. |
| 69 | The single-block program |
| 70 | .it uboot |
| 71 | will read a UNIX pathname from the console, |
| 72 | find the corresponding file on a device, |
| 73 | load that file into core location zero, |
| 74 | and transfer to it. |
| 75 | The current version of this boot program |
| 76 | reads a single character (either |
| 77 | .bd p |
| 78 | or |
| 79 | .bd k |
| 80 | for RP or RK, both drive 0) |
| 81 | to specify which device is to be |
| 82 | searched. |
| 83 | .it Uboot |
| 84 | operates under very |
| 85 | severe space constraints. |
| 86 | It supplies no prompts, except that it |
| 87 | echos a carriage return and line feed after the |
| 88 | .bd p |
| 89 | or |
| 90 | .bd k. |
| 91 | No diagnostic is provided if the indicated file cannot be found, |
| 92 | nor is there any means of correcting typographical errors in the |
| 93 | file name except to start the program over. |
| 94 | .it Uboot |
| 95 | can reside on any of the standard |
| 96 | file systems or may be loaded from a |
| 97 | .it tp |
| 98 | tape as described above. |
| 99 | .s3 |
| 100 | The standard DEC disk ROMs will load and execute |
| 101 | .it uboot |
| 102 | from block zero. |
| 103 | .s3 |
| 104 | .it "The switches.||" |
| 105 | The console switches play an important role in the |
| 106 | use and especially the booting of UNIX. |
| 107 | During operation, |
| 108 | the console switches are |
| 109 | examined 60 times per second, |
| 110 | and the contents of the address specified by the switches |
| 111 | are displayed in the display register. |
| 112 | (This is not true on the 11/40 |
| 113 | since there is no display register on that machine.) |
| 114 | If the switch address is even, |
| 115 | the address is interpreted in kernel (system) |
| 116 | space; |
| 117 | if odd, |
| 118 | the rounded-down address is interpreted in |
| 119 | the current user space. |
| 120 | .s3 |
| 121 | If any diagnostics are produced by the system, |
| 122 | they are printed on the console only if |
| 123 | the switches are non-zero. |
| 124 | Thus it is wise to have a non-zero value in the |
| 125 | switches at all times. |
| 126 | .s3 |
| 127 | During the startup of the |
| 128 | system, |
| 129 | the |
| 130 | .it init |
| 131 | program (VIII) |
| 132 | reads the switches and |
| 133 | will come up single-user |
| 134 | if the switches are set to 173030. |
| 135 | .s3 |
| 136 | It is unwise to have a non-existent address in the |
| 137 | switches. |
| 138 | This causes a bus error in the system |
| 139 | (displayed as 177777) |
| 140 | at the rate of 60 times per second. |
| 141 | If there is a transfer of more than |
| 142 | 16ms duration on a device with a data rate |
| 143 | faster than the bus error timeout |
| 144 | (approx 10\*us) |
| 145 | then a permanent disk non-existent-memory error will occur. |
| 146 | .s3 |
| 147 | .it "ROM programs.||" |
| 148 | Here are some programs which are suitable for |
| 149 | installing in read-only memories, |
| 150 | or for manual keying into core |
| 151 | if no ROM is present. |
| 152 | Each program is position-independent |
| 153 | but should be placed well above location 0 |
| 154 | so it will not be overwritten. |
| 155 | Each reads a block from the |
| 156 | beginning of a device into core location |
| 157 | zero. |
| 158 | The octal words constituting the program are |
| 159 | listed on the left. |
| 160 | .s3 |
| 161 | .ne 5 |
| 162 | .nf |
| 163 | DECtape (drive 0) from endzone: |
| 164 | .if n .ta 3 11 15 23 38 |
| 165 | .if t .ta .3i 1i 1.4i 2i 3.5i |
| 166 | 012700 mov $tcba,r0 |
| 167 | 177346 |
| 168 | 010040 mov r0,-(r0) / use tc addr for wc |
| 169 | 012710 mov $3,(r0) / read bn forward |
| 170 | 000003 |
| 171 | 105710 1: tstb (r0) / wait for ready |
| 172 | 002376 bge 1b |
| 173 | 112710 movb $5,(r0) / read (forward) |
| 174 | 000005 |
| 175 | 000777 br . / loop; now halt and start at 0 |
| 176 | .s3 |
| 177 | DECtape (drive 0) with search: |
| 178 | 012700 1: mov $tcba,r0 |
| 179 | 177346 |
| 180 | 010040 mov r0,-(r0) / use tc addr for wc |
| 181 | 012740 mov $4003,-(r0) / read bn reverse |
| 182 | 004003 |
| 183 | 005710 2: tst (r0) |
| 184 | 002376 bge 2b / wait for error |
| 185 | 005760 tst -2(r0) / loop if not end zone |
| 186 | 177776 |
| 187 | 002365 bge 1b |
| 188 | 012710 mov $3,(r0) / read bn forward |
| 189 | 000003 |
| 190 | 105710 2: tstb (r0) / wait for ready |
| 191 | 002376 bge 2b |
| 192 | 112710 movb $5,(r0) / read (forward) |
| 193 | 000005 |
| 194 | 105710 2: tstb (r0) / wait for ready |
| 195 | 002376 bge 2b |
| 196 | 005007 clr pc / transfer to zero |
| 197 | .s3 |
| 198 | .fi |
| 199 | Caution: both of these DECtape programs will (literally) blow a fuse |
| 200 | if 2 drives are dialed to zero. |
| 201 | .s3 |
| 202 | .nf |
| 203 | Magtape from load point: |
| 204 | 012700 mov $mtcma,r0 |
| 205 | 172526 |
| 206 | 010040 mov r0,-(r0) / usr mt addr for wc |
| 207 | 012740 mov $60003,-(r0) / read 9-track |
| 208 | 060003 |
| 209 | 000777 br . / loop; now halt and start at 0 |
| 210 | .s3 |
| 211 | RK (drive 0): |
| 212 | 012700 mov $rkmr,r0 |
| 213 | 177414 |
| 214 | 005040 clr -(r0) |
| 215 | 005040 clr -(r0) |
| 216 | 010040 mov r0,-(r0) |
| 217 | 012740 mov $5,-(r0) |
| 218 | 000005 |
| 219 | 105710 1: tstb (r0) |
| 220 | 002376 bge 1b |
| 221 | 005007 clr pc |
| 222 | .s3 |
| 223 | RP (drive 0) |
| 224 | 012700 mov $rpmr,r0 |
| 225 | 176726 |
| 226 | 005040 clr -(r0) |
| 227 | 005040 clr -(r0) |
| 228 | 005040 clr -(r0) |
| 229 | 010040 mov r0,-(r0) |
| 230 | 012740 mov $5,-(r0) |
| 231 | 000005 |
| 232 | 105710 1: tstb (r0) |
| 233 | 002376 bge 1b |
| 234 | 005007 clr pc |
| 235 | .dt |
| 236 | .sh FILES |
| 237 | /usr/sys/unix \*- UNIX code |
| 238 | .br |
| 239 | /usr/mdec/mboot \*- \fItp\fR magtape bootstrap |
| 240 | .br |
| 241 | /usr/mdec/tboot \*- \fItp\fR DECtape bootstrap |
| 242 | .br |
| 243 | /usr/mdec/uboot \*- file system bootstrap |
| 244 | .sh "SEE ALSO" |
| 245 | tp(I), init(VII) |