Sub-Isa Bus Interface; Boot Loader; Disk On Chip (Doc) - Micros Systems Workstation 4 LX Service Manual

As shown in Figure 2-5, two devices are located on the PCI Bus. U12 is a National
Semiconductor Corp DP83815 10/100 Ethernet Controller, and the optional
PCMCIA Daughter Card XB37 or XBRB37 includes a RL5C475II PCI to Card
Bus Controller. The PCMCIA Daughter Card was replaced by the Mini-PCI
Daughter Card XBRD68 in 2006.

Sub-ISA Bus Interface

Some features of the Sub-ISA Bus are listed below.
Two devices are attached to the Sub-ISA Bus. These are U24, a 39LF020 2Mbit
(256 x 8) Flash EEPROM Boot Loader installed in a 32-pin PLCC socket, and
U19, a 32M Disk On Chip installed in a 32-pin DIP socket.
• Supports the ROMCS output to select Flash EPROM boot loader chip
• Includes direct support for the M-Systems DiskOnChip

Boot Loader

The Boot Loader code is stored in Flash EEPROM U24. Similar in function to
the BIOS in Personal Computers, the boot loader is specific to the x86
compatible SC3200 processor. Executing at power-up, it contains all
power-up initalization code for each of the system board devices.
Once initalization is complete, the boot loader performs a custom Power On
Self Test of the primary system board components and copies the operating
system image from the Disk On Chip into system RAM.
The boot loader also contains custom extensions unique to the WS4 hardware.
These functions permit access to platform specific features such as persisting
the registry to the CF card and checking the CF card for an updated copy of
the operating system at boot time.

Disk On Chip (DOC)

The Disk On Chip 2000 is part of M-Systems third generation of Disk On
Chip products. It combines disk controller firmware with Flash Memory on a
single die, providing a cost effective solid state alternative to conventional
rotating media.
The DOC includes a copy of the Windows CE image contained in a hidden
partition. Each time the workstation starts, the Windows CE image is
transferred from the Disk On Chip to system RAM and started.
All Workstation 4s use a 32M DOC in a 32-pin Dual In Line (DIP) package.
The SC3200 is programmed to enable
in an 8K memory window starting at C8000H.
Workstation 4 and 4 LX Field Service Guide
WS4 Technical Overview
PCI and Sub-ISA Bus Interface
®
2000.
the DOC chip select output
DOCCS#,
2-9