1-10 Technical Information
System Memory
The system comes standard with 8 MB of memory (16 MB in multimedia configurations),
640 KB of base memory and 7 MB of extended memory. System memory can be expanded up
to 128 MB, using optional single in-line memory modules (SIMMs) installed in SIMM sockets.
Four SIMM sockets are integrated on the system board. Non-multimedia systems ship with two
4-MB SIMMs installed in two sockets. Multimedia configurations ship with two 8-MB SIMMs
installed in two sockets.
The SIMM memory sockets accept 4-, 8-, 16-, 32-, or 64-MB SIMMs, either 32-bit (no par-
ity) or 36-bit (parity). The factory installed high-speed RAM is 32 bits wide. SIMMs are 1 MB x
32 bit (4 MB), 2 MB x 32 bit (8 MB), 4 MB x 32 bit (16 MB), 8 MB x 32 bit (32 MB), and 16
MB x 32 bit (64 MB). When the standard SIMM(s) is removed, four 32-MB SIMMs may be
installed for a total of 128 MB.
CAUTION:
SIMMs must match the tin metal plat-
ing used on the system board SIMM sockets. When
adding SIMMs, use tin-plated SIMMs.
SIMMs install directly on the system board. Different size SIMMs may be intermixed.
Each SIMM is inserted into a socket or bank. The system board's four SIMM sockets are as-
signed as banks 0 through 3. For non-multimedia configurations, the standard 8 MB of memory is
installed in bank 0. The multimedia configurations have two 4 MB SIMMs installed in banks 0
and 1. See Section 3, Options, for installation instructions and SIMM memory configurations.
Interrupt Controller
The interrupt controller operates as an interrupt manager for the entire AT system environment.
The controller accepts requests from peripherals, issues interrupt requests to the processor, re-
solves interrupt priorities, and provides vectors for the processor to determine which interrupt
routine to execute. The interrupt controller has priority assignment modes that can be reconfigured
at any time during system operations.
The interrupt levels are described in Table Section 1-4. Interrupt-level assignments 0 through 15
are in order of decreasing priority. See Section 2, Setup and Operation, for information on
changing the interrupts using Setup.
Table Section 1-4 Interrupt Level Assignments
Interrupt Priority
Interrupt Device
IRQ00
Counter/Timer
IRQ01
Keyboard
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