SECTION 7
Reference, System Information
7-4 PEN*KEY
R
6100 Computer Programmer’s Reference Guide
In standard PCs, the CMOS RAM is usually the only memory maintained by a
backup battery. In contrast, all memory in the PEN*KEY computer is mainĆ
tained at all times, with a fully charged backup battery. This memory can be
maintained for approximately 200 hours in the event of a main battery failure.
The CMOS RAM is special only because the PCĆcompatible software expects the
CMOS RAM to exist and to contain certain configuration values.
Invalid RamDrive Message
One of the first tests involving extended memory verifies that the RAM drive, if
it exists, is not corrupted by a power failure. If the RAM drive signature is corĆ
rupted, the RAM drive is removed and the default boot drive is set to drive A.
The
Invalid RamDrive
message is then displayed and a single beep is issued.
Testing XMS Memory Message
This message displays while the POST of extended memory is performed. The
initials
XMS
refer to the e
X
tended
M
emory
S
pecification published by Lotus, InĆ
tel, Microsoft, and AST Research. The XMS specification describes a program
interface for accessing extended memory, the high memory area (HMA), and upĆ
per memory. You hear a clicking sound while the extended memory test is under
way. One click occurs for each 64K segment of memory tested. Immediately
following the extended memory test, a screen display indicates the quantity of
memory that was found and tested. Any memory allocated to a RAM drive is not
included in either the testing or reporting of available XMS memory.
Flash Memory Size Report
The size of the flash memory is reported on each boot cycle. There is no test asĆ
sociated with this display, but there is the possibility that an incorrect size could
be reported if a hardware problem existed.
BIOS Extensions are Scanned For and Installed
After most of the POSTs have ended, the ROM BIOS scan through system
memory in the address range of E800:0 through F7FF:F, looking for BIOS extenĆ
sions. On PCĆcompatible computers, a BIOS extension is any software or firmĆ
ware that runs prior to the time that the operating system is loaded. BIOS exĆ
tensions execute directly from writeĆprotected memory, such as ROM or shadow
RAM. A special signature precedes each BIOS extension. After that signature is
validated, the corresponding BIOS extension is made active (or
posted
). CurrentĆ
ly the 6100 Computer includes the following BIOS extensions: the VGA BIOS
(VGABIOS.BIN) and ROM DOS 5 (ROMDOSLO.BIN).
The VGA BIOS is located and executed prior to this stage of the boot process
since it resides in the address range of C000:0 through CFFF:F. ROM DOS 5 itĆ
self is located at F000:0. That leaves 32 kilobytes of shadow RAM between
E800:0 and EFFF:F that serves the same function as an option ROM socket in a
traditional PC environment. If a BIOS extension signature is found at address
E800:0, these 32 kilobytes of shadow RAM is scanned for BIOS extensions and
remains resident as writeĆprotected RAM. If no signature is found, the address
range is redirected back to the ISA bus for use by PC Card adapters.
ROM DOS 5 is Booted
When the DOS 5 option ROM is posted (as a BIOS extension), it replaces interĆ
rupt 19h with a vector that points back into the ROM DOS 5 code. It then reĆ
turns to the BIOS without making any other system changes. After the BIOS
has finished scanning for all BIOS extensions, it issues an interrupt 19h to boot
7. Reference,
System Information
Содержание PEN*KEY 6100
Страница 1: ...PEN KEYR 6100 Computer PROGRAMMER S REFERENCE GUIDE P N 977 054 001 Revision B December 2000 ...
Страница 14: ...CONTENTS xii PEN KEYR 6100 Computer Programmer s Reference Guide ...
Страница 22: ...Preface 8 PEN KEYR 6100 Computer Programmer s Reference Guide PREFACE ...
Страница 112: ...SECTION 4 Power Management 4 10 PEN KEYR 6100 Computer Programmer s Reference Guide 4 Power Management ...
Страница 318: ...GENERAL INDEX Index 6 PEN KEYR 6100 Computer Programmer s Reference Guide ...