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COMPAQ DeskPro 386

DeskPro 386 configurations currently include:

All configurations currently use IBM display adapters. Configurations with COMPAQ Monochrome Graphics, COMPAQ Enhanced Graphics, and COMPAQ VGA will eventually be added as well.

COMPAQ DeskPro 386/25 Technical Reference Guide

Originally, all we had was the first volume of DeskPro 386/25 Technical Reference Guide. Its table of contents gave us a taste of what was in Volume II:

Fortunately, PCjs was later able to acquire both volumes of the original DeskPro 386/16 Technical Reference, so we have much more than a “taste” now.

COMPAQ DeskPro 386/25 Technical Reference Guide (Volume I)

NOTE: As the page on COMPAQ DeskPro 386 ROMs explains, 5 COMPAQ engineers had their initials “engraved” in the original DeskPro 386 ROM. In June 2018, I was fortunate enough to meet 4 of them, and they were all kind enough to sign my copy of the DeskPro 386 Technical Reference Guide. This “signature page”, shown below, has since been added to the PDF above.

COMPAQ DeskPro 386-25 Technical Reference Guide - Volume 1 - 1988-08 - Signatures

COMPAQ DeskPro 386 Reference Highlights

Fixed Disk Drive Parameter Table Values

The first table comes from pages 4-119 and 4-120 of the DeskPro 386/16 Technical Reference Guide (Volume I), dated September 1986 (First Edition). These are the values used by PCjs in driveinfo.js for COMPAQ machines.

Note that COMPAQ calculated raw capacity by multiplying cylinders, heads, and sectors per track by 512 bytes per sector and then dividing the total by 1,000,000, a common industry practice that “inflated” disk capacity. PCjs considers 1 megabyte (Mb) to be 1,048,576 bytes (1024 x 1024), so any capacity calculations that PCjs reports will be smaller than the values shown below.

                                      Landing
                          Pre-comp.    Zone
Drive             Max.    Cylinder    Cylinder   Sectors/   Capacity    Same as
Type  Cylinders   Heads   (note 1)    (note 2)    Track       (MB)      IBM PC AT
---------------------------------------------------------------------------------
  1      306       4        128         305        17        10.65      Yes
  2      615       4        128         638        17        21.41      Yes
  3      615       6        128         615        17        32.12      Yes
  4     1024       8        512        1023        17        71.30
  5      940       6        512         939        17        49.09      Yes
  6      697       5        128         696        17        30.33
  7      462       8        256         511        17        32.17      Yes
  8      925       5        128         924        17        40.26
  9      900      15         No         899        17       117.50      Yes
 10      980       5         No         980        17        42.65
 11      925       7        128         924        17        56.36
 12      925       9        128         924        17        72.46
 13      612       8        256         611        17        42.61
 14      980       4        128         980        17        34.12
 15        0       0          0           0         0            0
 16      612       4          0         612        17        21.31      Yes
 17      980       5        128         980        17        42.65
 18      966       6        128         966        17        50.45
 19     1023       8         No        1023        17        71.23
 20      733       5        256         732        17        31.90      Yes
 21      733       7        256         732        17        44.66      Yes
 22      768       6         No         768        17        40.11      
 23      771       6         No         771        17        20.16
 24      966      14         No         966        17       117.71
 25      966      16         No         966        17       134.53
 26     1023      14         No        1023        17       124.66
 27      966      10         No         966        17        84.08
 28      771       3         No         771        17        20.11
 29      578       4         No         578        17        20.09
 30      615       4        128         615        25        31.49
 31      615       8        128         615        25        62.98
 32      966       3         No         966        34        50.45
 33      966       5         No         966        34        84.08
 34      966       7         No         966        34       117.71
 35      966       8         No         966        34       134.53
 36      966       9         No         966        34       151.35
 37      966       5         No         966        34        84.08
 38     1023       9         No        1023        33       155.56
 39     1023      11         No        1023        33       190.13
 40     1023      13         No        1023        33       224.70
 41     1023      15         No        1023        33       259.27
 42     1023      16         No        1023        34       284.93
 43      756       4         No         756        26        40.26
 44      756       2         No         756        26        20.13
 45      768       4         No         768        26        40.89
 46      768       2         No         768        26        20.45
 47      966       5        128         966        25        61.82
---------------------------------------------------------------------------------

The next table comes from pages 4-189 and 4-190 of the DeskPro 386/25 Technical Reference Guide (Volume I), dated August 1988 (First Edition). Note that the table is largely identical to the earlier version above, except for drive types marked by *. There are also 3 entries marked by ** that warrant further investigation, because they specify more than 1024 cylinders, which the INT 13H BIOS interface at that time did not support.

                                             Landing
                                 Pre-comp.    Zone
Drive                    Max.    Cylinder    Cylinder   Sectors/   Capacity     Same as
Type         Cylinders   Heads   (note 1)    (note 2)    Track       (MB)       IBM PC AT
-----------------------------------------------------------------------------------------
  1  (note 3)   306       4        128         305        17        10.65       Yes
  2  (note 3)   615       4        128         638        17        21.41       Yes
  3             615       6        128         615        17        32.12       Yes
  4            1024       8        512        1023        17        71.30
  5             940       6        512         939        17        49.09       Yes
  6  (note 3)   697       5        128         696        17        30.33
  7             462       8        256         511        17        32.17       Yes
  8             925       5        128         924        17        40.26
  9             900      15         -1         899        17       117.50       Yes
 10             980       5         -1         980        17        42.65
 11             925       7        128         924        17        56.36
 12  (note 3)   925       9        128         924        17        72.46
 13             612       8        256         611        17        42.61
 14             980       4        128         980        17        34.12
 15     Reserved - Not for use by end-users
 16             612       4          0         612        17        21.31       Yes
 17             980       5        128         980        17        42.65
 18             966       6        128         966        17        50.45
 19            1023       8         -1        1023        17        71.23
 20             733       5        256         732        17        31.90       Yes
 21             733       7        256         732        17        44.66       Yes
 22*            524       4         -1         524        40        42.93
 23*            924       8         -1         924        17        64.34
 24             966      14         -1         966        17       117.71
 25  (note 3)   966      16         -1         966        17       134.53
 26            1023      14         -1        1023        17       124.66
 27*            832       6         -1         832        33        84.34
 28**          1222      15         -1        1222        34       319.09
 29**          1240       7         -1        1240        34       151.10
 30             615       4        128         615        25        31.49
 31             615       8        128         615        25        62.98
 32*            905       9        128         905        25       104.26
 33* (note 3)   832       8         -1         832        33       112.46
 34             966       7         -1         966        34       117.71
 35  (note 3)   966       8         -1         966        34       134.53
 36             966       9         -1         966        34       151.35
 37             966       5         -1         966        34        84.08
 38* (note 3)   611      16         -1         611        63       315.33
 39            1023      11         -1        1023        33       190.13
 40*           1023      15         -1        1023        34       267.13
 41**          1630      15         -1        1630        52       650.96
 42*           1023      16         -1        1023        63       527.97
 43*            805       4         -1         805        26        42.86
 44*            805       2         -1         805        26        21.43
 45* (note 3)   748       8         -1         748        33       101.11
 46*            748       6         -1         748        33        75.83
 47  (note 3)   966       5        128         966        25        61.82
-----------------------------------------------------------------------------------------
NOTES: 1.  A value of -1 means that no write precompensation is used.
       2.  These values are not used by the COMPAQ DESKPRO 386/25 system, which
           automatically retracts and locks the heads in a non-data landing zone
           at power-down.
       3.  Drive types supported by Compaq.
-----------------------------------------------------------------------------------------

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