Publication No: 500-9300007768-000 Rev. H.0
Standard Features 37
The V7768/V7769 include 32 KByte of non-volatile SRAM which can be accessed
by the CPU at any time, and is used to store system data that must not be lost
during power-off conditions.
NOTE
Memory capacity may be extended as parts become available.
2.3 Memory Map
2.4 I/O Port Map
Like a desktop system, the V7768/V7769 include special input/output instructions
that access I/O peripherals residing in I/O addressing space (separate and distinct
from memory addressing space). Locations in I/O address space are referred to as
ports
. When the CPU decodes and executes an I/O instruction, it produces a 16-bit
I/O address on lines A00 to A15 and identifies the I/O cycle with the M/I/O control
line. Thus, the CPU includes an independent 64 KByte I/O address space, which is
accessible as bytes, words or longwords.
Standard hardware circuitry reserves only 1,024 byte of I/O addressing space
from I/O $000 to $3FF for peripherals. All standard PC I/O peripherals, such as
serial and parallel ports, hard and floppy drive controllers, video system, real-
time clock, system timers and interrupt controllers are addressed in this region of
I/O space. The BIOS initializes and configures all these registers properly;
adjusting these I/O ports directly is not normally necessary.
The assigned and user-available I/O addresses are summarized in the I/O
Address Map,
Table 2-1 Memory Map
Mode
Memory Address Range
Size
Description
Protected Mode
$FFFF 0000 - $FFFF FFFF
64 KByte
ROM BIOS Image
$C000 0000 - $FFFE FFFF
0.9 GByte
Unused*
$0010 0000 - $BFFF FFFF
3 GByte
Reserved for **
Onboard Extended Memory
(not filled on all systems)
Real Mode
$E0000 - $FFFFF
128 KByte
$C0000 - $DFFFF
128 KByte
$A0000 - $BFFFF
128 KByte
$00000 - $9FFFF
640 KByte
* This space can be used to set up protected mode PCI-to-VME windows (also referred to as PCI slave images). BIOS
will also map onboard PCI based NVRAM, Timers and Watchdog Timers in this area.
** This space can be allocated as shared memory (for example, between the BGA CPU and VME Master). Note that if a
PMC board is loaded, the expansion BIOS may be placed in this area.
