CD-ROM Position After a Hold

Compares GetlocL with GetlocP during a read that follows a 20 second pause and during a read with no pause.

Overview

The probe compares the positions that GetlocL and GetlocP answer during a read, which the CD-ROM commands page describes. ATV - Quad Power Racing is in the drive, every interrupt is polled, and root counter 2 counts system clock cycles divided by 8.¹

In pass 1 the probe reads 8 sectors at 26:00:00 at double speed, pauses, and holds for 20 seconds. It then reads from 26:00:00 again, times 32 INT1 interrupts and sends 16 pairs of GetlocL and GetlocP while the read goes on. Pass 2, the control, reads at single speed from 00:15:25 with no hold.¹

Results

GetlocP ran 1 or 2 sectors ahead of GetlocL in every pair after the 20 second hold and in every pair of the control. In pass 1 the difference was 2 sectors in 12 of 16 pairs, and in pass 2 it was 1 sector in 7 of 16 and 2 sectors in 9.¹

The read after the hold delivered its first sector 26.9 ms after ReadN. The first read of the pass, before the hold, took 1247 ms to its first sector, and the control's first sector came after 1036 ms.¹

At double speed the sectors of the read after the hold came 26000 to 30000 ticks apart. The average spacing was 6.6 ms.¹

Runs

Run 5501a-link on 16 October 2026

Raw output: CDHOLD.txt

CDHOLD.txt:

CDHOLD start
CDHOLD 1 H Setmode t 6993 INT3 12
CDHOLD 1 H h-Setloc t 4822 INT3 12
CDHOLD 1 H h-ReadN t 5400 INT3 12
CDHOLD 1 H INT1-1 t 5280520 INT1 32
CDHOLD 1 H INT1-2 t 5308940 INT1 32
CDHOLD 1 H INT1-3 t 5335744 INT1 32
CDHOLD 1 H INT1-4 t 5367176 INT1 32
CDHOLD 1 H INT1-5 t 5393284 INT1 32
CDHOLD 1 H INT1-6 t 5420316 INT1 32
CDHOLD 1 H INT1-7 t 5451982 INT1 32
CDHOLD 1 H INT1-8 t 5478018 INT1 32
CDHOLD 1 H h-Pause t 10149 INT3 32
CDHOLD 1 H h-Pause-2 t 422233 INT2 12
CDHOLD 1 H Setloc t 5824 INT3 12
CDHOLD 1 H ReadN t 5448 INT3 12
CDHOLD 1 H INT1-1 t 113974 INT1 32
CDHOLD 1 H INT1-2 t 143346 INT1 32
CDHOLD 1 H INT1-3 t 169550 INT1 32
CDHOLD 1 H INT1-4 t 197610 INT1 32
CDHOLD 1 H INT1-5 t 227522 INT1 32
CDHOLD 1 H INT1-6 t 253794 INT1 32
CDHOLD 1 H INT1-7 t 281846 INT1 32
CDHOLD 1 H INT1-8 t 312168 INT1 32
CDHOLD 1 H INT1-9 t 338546 INT1 32
CDHOLD 1 H INT1-10 t 367376 INT1 32
CDHOLD 1 H INT1-11 t 395338 INT1 32
CDHOLD 1 H INT1-12 t 423324 INT1 32
CDHOLD 1 H INT1-13 t 451386 INT1 32
CDHOLD 1 H INT1-14 t 480956 INT1 32
CDHOLD 1 H INT1-15 t 509058 INT1 32
CDHOLD 1 H INT1-16 t 536342 INT1 32
CDHOLD 1 H INT1-17 t 564404 INT1 32
CDHOLD 1 H INT1-18 t 592264 INT1 32
CDHOLD 1 H INT1-19 t 620328 INT1 32
CDHOLD 1 H INT1-20 t 649590 INT1 32
CDHOLD 1 H INT1-21 t 677588 INT1 32
CDHOLD 1 H INT1-22 t 705246 INT1 32
CDHOLD 1 H INT1-23 t 733298 INT1 32
CDHOLD 1 H INT1-24 t 762284 INT1 32
CDHOLD 1 H INT1-25 t 790438 INT1 32
CDHOLD 1 H INT1-26 t 818556 INT1 32
CDHOLD 1 H INT1-27 t 847762 INT1 32
CDHOLD 1 H INT1-28 t 875262 INT1 32
CDHOLD 1 H INT1-29 t 903256 INT1 32
CDHOLD 1 H INT1-30 t 932826 INT1 32
CDHOLD 1 H INT1-31 t 959428 INT1 32
CDHOLD 1 H INT1-32 t 987426 INT1 32
CDHOLD 1 H GetlocL t 999208 INT3 26 00 31 02 01 01 48 00
CDHOLD 1 H GetlocP t 1017016 INT3 01 01 25 58 33 26 00 33
CDHOLD 1 H GetlocL t 1019044 INT1 32
CDHOLD 1 H GetlocL t 1026250 INT3 26 00 32 02 01 01 48 00
CDHOLD 1 H GetlocP t 1038778 INT3 01 01 25 58 34 26 00 34
CDHOLD 1 H GetlocL t 1047566 INT3 26 00 33 02 01 01 64 05
CDHOLD 1 H GetlocP t 1049526 INT1 32
CDHOLD 1 H GetlocP t 1056732 INT3 01 01 25 58 34 26 00 34
CDHOLD 1 H GetlocL t 1069570 INT3 26 00 33 02 01 01 64 05
CDHOLD 1 H GetlocP t 1079546 INT3 01 01 25 58 35 26 00 35
CDHOLD 1 H GetlocL t 1081572 INT1 32
CDHOLD 1 H GetlocL t 1094558 INT3 26 00 34 02 01 01 48 00
CDHOLD 1 H GetlocP t 1104954 INT3 01 01 25 58 36 26 00 36
CDHOLD 1 H GetlocL t 1106980 INT1 32
CDHOLD 1 H GetlocL t 1114186 INT3 26 00 35 02 01 01 48 00
CDHOLD 1 H GetlocP t 1129976 INT3 01 01 25 58 37 26 00 37
CDHOLD 1 H GetlocL t 1131998 INT1 32
CDHOLD 1 H GetlocL t 1139204 INT3 26 00 36 02 01 01 48 00
CDHOLD 1 H GetlocP t 1151930 INT3 01 01 25 58 38 26 00 38
CDHOLD 1 H GetlocL t 1160726 INT3 26 00 37 02 01 01 48 00
CDHOLD 1 H GetlocP t 1162752 INT1 32
CDHOLD 1 H GetlocP t 1169958 INT3 01 01 25 58 38 26 00 38
CDHOLD 1 H GetlocL t 1182556 INT3 26 00 37 02 01 01 48 00
CDHOLD 1 H GetlocP t 1192898 INT3 01 01 25 58 39 26 00 39
CDHOLD 1 H GetlocL t 1194918 INT1 32
CDHOLD 1 H GetlocL t 1207920 INT3 26 00 38 02 01 01 48 00
CDHOLD 1 H GetlocP t 1217902 INT3 01 01 25 58 40 26 00 40
CDHOLD 1 H GetlocL t 1219860 INT1 32
CDHOLD 1 H GetlocL t 1227067 INT3 26 00 39 02 01 01 48 00
CDHOLD 1 H GetlocP t 1243192 INT3 01 01 25 58 41 26 00 41
CDHOLD 1 H GetlocL t 1245148 INT1 32
CDHOLD 1 H GetlocL t 1252354 INT3 26 00 40 02 01 01 48 00
CDHOLD 1 H GetlocP t 1264884 INT3 01 01 25 58 42 26 00 42
CDHOLD 1 H GetlocL t 1273686 INT3 26 00 41 02 01 01 48 00
CDHOLD 1 H GetlocP t 1275712 INT1 32
CDHOLD 1 H GetlocP t 1283338 INT3 01 01 25 58 42 26 00 42
CDHOLD 1 H GetlocL t 1299580 INT3 26 00 42 02 01 01 48 00
CDHOLD 1 H GetlocP t 1301606 INT1 32
CDHOLD 1 H GetlocP t 1308812 INT3 01 01 25 58 43 26 00 43
CDHOLD 1 H GetlocL t 1321344 INT3 26 00 42 02 01 01 48 00
CDHOLD 1 H GetlocP t 1331560 INT3 01 01 25 58 44 26 00 44
CDHOLD 1 H GetlocL t 1333514 INT1 32
CDHOLD 1 H GetlocL t 1340720 INT3 26 00 43 02 01 01 48 00
CDHOLD 1 H GetlocP t 1356536 INT3 01 01 25 58 45 26 00 45
CDHOLD 1 H Pause t 1893 INT1 32
CDHOLD 1 H Pause t 9099 INT3 32
CDHOLD 1 H Pause-2 t 400165 INT2 12
CDHOLD 2 C Setmode t 2730 INT3 12
CDHOLD 2 C Setloc t 19280 INT3 12
CDHOLD 2 C ReadN t 9935 INT3 12
CDHOLD 2 C INT1-1 t 4386283 INT1 32
CDHOLD 2 C INT1-2 t 4442583 INT1 32
CDHOLD 2 C INT1-3 t 4497679 INT1 32
CDHOLD 2 C INT1-4 t 4554431 INT1 32
CDHOLD 2 C INT1-5 t 4611603 INT1 32
CDHOLD 2 C INT1-6 t 4667047 INT1 32
CDHOLD 2 C INT1-7 t 4723919 INT1 32
CDHOLD 2 C INT1-8 t 4781691 INT1 32
CDHOLD 2 C INT1-9 t 4836611 INT1 32
CDHOLD 2 C INT1-10 t 4894143 INT1 32
CDHOLD 2 C INT1-11 t 4949877 INT1 32
CDHOLD 2 C INT1-12 t 5006095 INT1 32
CDHOLD 2 C INT1-13 t 5064839 INT1 32
CDHOLD 2 C INT1-14 t 5118393 INT1 32
CDHOLD 2 C INT1-15 t 5175715 INT1 32
CDHOLD 2 C INT1-16 t 5232405 INT1 32
CDHOLD 2 C INT1-17 t 5288413 INT1 32
CDHOLD 2 C INT1-18 t 5344301 INT1 32
CDHOLD 2 C INT1-19 t 5403105 INT1 32
CDHOLD 2 C INT1-20 t 5458045 INT1 32
CDHOLD 2 C INT1-21 t 5514665 INT1 32
CDHOLD 2 C INT1-22 t 5570439 INT1 32
CDHOLD 2 C INT1-23 t 5627329 INT1 32
CDHOLD 2 C INT1-24 t 5684121 INT1 32
CDHOLD 2 C INT1-25 t 5739693 INT1 32
CDHOLD 2 C INT1-26 t 5796061 INT1 32
CDHOLD 2 C INT1-27 t 5852663 INT1 32
CDHOLD 2 C INT1-28 t 5908611 INT1 32
CDHOLD 2 C INT1-29 t 5965231 INT1 32
CDHOLD 2 C INT1-30 t 6022013 INT1 32
CDHOLD 2 C INT1-31 t 6078271 INT1 32
CDHOLD 2 C INT1-32 t 6135977 INT1 32
CDHOLD 2 C GetlocL t 6147955 INT3 00 15 56 02 01 00 00 00
CDHOLD 2 C GetlocP t 6153427 INT3 01 01 00 13 57 00 15 57
CDHOLD 2 C GetlocL t 6160553 INT3 00 15 56 02 01 00 00 00
CDHOLD 2 C GetlocP t 6173481 INT3 01 01 00 13 58 00 15 58
CDHOLD 2 C GetlocL t 6180267 INT3 00 15 56 02 01 00 00 00
CDHOLD 2 C GetlocP t 6185737 INT3 01 01 00 13 58 00 15 58
CDHOLD 2 C GetlocL t 6195961 INT3 00 15 57 02 01 01 64 01
CDHOLD 2 C GetlocP t 6197987 INT1 32
CDHOLD 2 C GetlocP t 6205193 INT3 01 01 00 13 58 00 15 58
CDHOLD 2 C GetlocL t 6210237 INT3 00 15 57 02 01 01 64 01
CDHOLD 2 C GetlocP t 6215707 INT3 01 01 00 13 58 00 15 58
CDHOLD 2 C GetlocL t 6230581 INT3 00 15 57 02 01 01 64 01
CDHOLD 2 C GetlocP t 6236051 INT3 01 01 00 13 59 00 15 59
CDHOLD 2 C GetlocL t 6242769 INT3 00 15 57 02 01 01 64 01
CDHOLD 2 C GetlocP t 6251581 INT3 01 01 00 13 59 00 15 59
CDHOLD 2 C GetlocL t 6253537 INT1 32
CDHOLD 2 C GetlocL t 6260744 INT3 00 15 58 02 01 02 64 01
CDHOLD 2 C GetlocP t 6266027 INT3 01 01 00 13 59 00 15 59
CDHOLD 2 C GetlocL t 6272805 INT3 00 15 58 02 01 02 64 01
CDHOLD 2 C GetlocP t 6285735 INT3 01 01 00 13 60 00 15 60
CDHOLD 2 C GetlocL t 6292795 INT3 00 15 58 02 01 02 64 01
CDHOLD 2 C GetlocP t 6298337 INT3 01 01 00 13 60 00 15 60
CDHOLD 2 C GetlocL t 6308327 INT3 00 15 59 02 01 03 64 01
CDHOLD 2 C GetlocP t 6310281 INT1 32
CDHOLD 2 C GetlocP t 6317487 INT3 01 01 00 13 60 00 15 60
CDHOLD 2 C GetlocL t 6322771 INT3 00 15 59 02 01 03 64 01
CDHOLD 2 C GetlocP t 6328313 INT3 01 01 00 13 60 00 15 60
CDHOLD 2 C GetlocL t 6342555 INT3 00 15 59 02 01 03 64 01
CDHOLD 2 C GetlocP t 6348027 INT3 01 01 00 13 61 00 15 61
CDHOLD 2 C GetlocL t 6355207 INT3 00 15 59 02 01 03 64 01
CDHOLD 2 C GetlocP t 6363953 INT3 01 01 00 13 61 00 15 61
CDHOLD 2 C GetlocL t 6365979 INT1 32
CDHOLD 2 C GetlocL t 6373185 INT3 00 15 60 02 01 04 64 01
CDHOLD 2 C GetlocP t 6378229 INT3 01 01 00 13 61 00 15 61
CDHOLD 2 C GetlocL t 6385181 INT3 00 15 60 02 01 04 64 01
CDHOLD 2 C GetlocP t 6398109 INT3 01 01 00 13 62 00 15 62
CDHOLD 2 C Pause t 5466 INT3 32
CDHOLD 2 C Pause-2 t 492650 INT2 12
CDHOLD done

References