Intermec 6100 Reference Guide

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the system.  At this point, ROM DOS 5 displays its startup message and takes

control of the system.  The bootstrap code written for ROM DOS 5 prepares an

environment very similar to the environment used by the diskĆbased MSĆDOS 5

product.  The primary difference is that much of ROM DOS executes directly

from shadow RAM instead of from conventional memory.  All DOS variables and

a significant amount of code are still located at the traditional address of 70:0h.
The sole function of the ROM DOS BIOS extension is to load and execute ROM

DOS directly from memory instead of loading it from a disk drive.  The ROM

DOS BIOS extension is enhanced to add the ability to select any of the primary

DOS drives as the default boot drive rather than being limited to A: or C:.

One of the first interactions between ROM DOS 5 and the ROM BIOS is the initĆ

ialization of DOS drives.  Using interrupt 13h, the ROM BIOS supports two

drives, as follows:

"

Drive 0 = A:, the first PC Card slot.  With the 6100 Computer display toĆ

ward you, drive A: is toward the rear of the unit.

"

Drive 1 = B:, the second PC Card slot (also used for Master Mode booting)

Refer to Figure 1Ć1, Location of Reset Button and PC Card Drives on page 1Ć17,

in the Getting Started section, for the location of the PC Card slots.
A DOS 5 embedded device driver uses Interrupt 15h, Function 87h (move exĆ

tended memory), to access both the RAM drive (drive C:) and the flash drive data

(drive D:).  ROM DOS 5 obtains the starting address for each drive by reading

values stored in the BIOS data area of system memory.

Drives A through F are supported as boot drives.  SRAM cards are recognized as

drives A and B.  ATA cards are recognized as drives E and F.

Once ROM DOS has initialized, it reads and processes the CONFIG.SYS file on

the default drive.  By now, the default drive is chosen, by means of the boot selecĆ

tion process, discussed in the following paragraphs.  If CONFIG.SYS does not

exist, no error or warning is displayed.
See Appendix A, Sample Configuration Files, for example CONFIG.SYS files.

The default command shell for ROM DOS 5 is:

SHELL=D:\COMMAND.COM /P D:\

After COMMAND.COM is loaded by this shell statement, AUTOEXEC.BAT is

processed.

Note that drives E through H are supported, where previous drive letters (A and

B) can be assigned drive letters in the range of E through H.

A warm boot is only slightly different from a cold boot.  Since the two forms of

booting are similar, this publication may refer to booting without specifying

warm or cold, except in cases where the form of boot is important for the underĆ

standing of the topic.