Aaeon PCM-4330 Instructions Manual page 12

The PCM-4330 serves as a processor board in a PC/104 environment and provides
for a fully ISA-compatible computer system.
The system is built using the SIS-85C47i. This chip contains on a single VLSI
component the main elements of an ISA system by implementing DMA, memory,bus,
interrupt controller, memory mapper, and timer.
For addressing peripheral devices, a chip from Standard Microsystem Corpora-
tion (SMC) is used on the board. The FDC37C92x-Ultra-I/O-Controller, built in
SuperCel technology, includes IDE-/AT-bus, floppy disk, keyboard, serial, and
TM
parallel port controllers, as well as a real-time clock.
The WD90C24 controller, addressing 1 MB of video memory via a 32 bit wide
data bus, is used to control video output. The controller accelerates the screen dis-
play of window systems like MS-Windows by hardware support of CPU intensive
screen operations. The graphics board supports all VGA, SVGA and Paradise en-
hanced video modes.
The PCM-4330 board is AT-compatible including all interfaces. All software writ-
ten for Intel 8086, 80286, 80386, 80486, and compatible processors runs on this
board. It is built and fired in double-sided SMD technology requiring minimum
space for a maximum of functions.
The 486SX, 486DX2, and 486DX4 CPUs offer virtual addressing capabilities, inte-
grated MMU, 4-level memory protection in multi-user-mode (Protected Virtual
Address Mode). 1 MB physical memory can be addressed in Real-Address-Mode
and 4 GB in Protected Mode. Maximum virtual memory in Protected Mode is 64
TB.
All DX-CPUs used for the PowerDwarf feature on-chip math co-processors.
Presently available CPUs from the i486 family include 8 kB 4-way-on-chip-cache
used for data and code caching by the CPU.
With respect to the 486SX, 486DX2, and 486DX4 CPU capabilities, main memory
is addressed with an access width of 32 bit. RAM memory is parity checked. Two
DRAM modules with access times of 70 ns are used in sockets providing 1 MB
with/without parity (256K x 16 or 256K x 18), 4MB with/without parity (1M x16 or
1M x 18), or 16MB (4M x 16) on-board system memory.