Rockwell Automation 6182 SDK - Manual (Page 8)

1–2 Introduction to the RAC6182
Publication 6182-UM002B-EN-P
System Timers
At least one (and in some cases, depending on the hardware revision
level, more than one) programmable hardware timer is available at the
application layer.
Memory Devices
Disk-On-Chip Flash ROM
The Disk-On-Chip device (commonly called the “DOC”) is a flash ROM
(32MB to 256MB, field upgradable) that emulates a disk device. The
Disk-On-Chip device has two partitions or logical storage areas. One
partition provides non-volatile storage for the Windows CE operating
system image. The other partition supports a FAT16 (DOS compatible)
file system, in which application programs and data can be stored.
Boot ROM
The boot code resides in a 256KB boot ROM. The boot code includes a
“Boot Loader” that loads the Windows CE image from the Disk-On-Chip
into DRAM at system startup.
The boot ROM is segmented into two 128K blocks, each of which
contains boot code. A jumper on the CPU board (J2) selects between the
2 blocks. The lower block (selected when the jumper is across pins 1
and 2) contains the primary boot code. The upper block (selected when
the jumper is across pins 2 and 3) contains boot code with debug support.
The upper block boot code performs extended power on self testing
(POST), disables restoration of user persistent registry items, and enables
debug output on COM2.
DRAM
The RAC6182 uses industry standard 3.3V, PC100 and SPD compliant,
non-ECC dynamic RAM, packaged in a DIMM. The DIMM may be
32MB to 256 MB, and is field upgradable. The DRAM provides a fast
access volatile storage space for data and program code.
The Operating System uses part of the RAM for a RAMDISK and the
other part for normal system memory. The RAMDISK portion is known
as the Object Store and provides specialized storage for the Windows CE
Registry and Windows CE system databases. The Windows CE Control
Panel System Properties tool has a slider control that allows a user to
determine how the RAM is allocated between RAMDISK Storage and
system memory. The slider control is factory set for a 50/50 split.
Application programs can control RAM allocation with the Windows CE
system call SetSystemMemoryDivision (see Microsoft’s documentation
of the CE API for details).