Information Technology Reference
In-Depth Information
Note these statements can also be inserted after the
__asm
keyword, such as:
__asm mov dx,0x01; /* COM2: */
__asm mov al,0xD2; /* serial port parameters */
__asm mov ah,0x0; /* initialize serial port */
__asm int 14h;
__asm line_status=ah;
__asm modem_status=al;
2.4
PC Systems
In selecting a PC many different components must be considered, especially in the way that
they connect. Figure 2.21 outlines some of the component parts and the decisions that have
to be made on each component.
+
+
Processor:
Type
Cache size (Level-1)
Clock speed
+
Graphics:
Type (Chipset)
Processing (3D/Accelerator)
Memory (Local memory)
Socket (SEC/Socket)
Interface (PCI/AGP)
+
Internal Busses:
ISA
PCI
IDE
+
Memory:
Type (DIMM/SDRAM/SIMM)
Cache (Level-2)
Speed
AGP
+
External Busses:
Parallel Port
Serial Port
SCSI
USB
Storage:
+
Type (Optical/Hard disk/Floppy disk)
Interface (SCSI/IDE)
Capacity (KB/MB/GB)
Figure 2.21
PC components
The Top 5 things that affect the
general
performance of a PC (in ranked order) are:
1.
Processor
. The type of the processor, its speed, its socket (which helps in upgrading in
the future), its interface to Level-2 cache, and so on. Additionally, MMX
TM
, (which is an
Intel trademark, but many read it as MultiMedia eXtension) can speed-up multi-media
applications.
2.
Local Memory
. Most operating systems can run multiple programs, each of which re-
quire their own memory space. When the system runs out of electronic memory (local
memory), it uses the hard disk for an extra storage (to create a virtual memory). Hard
disk accesses are much slower than electronic memory, thus the system is severely
slowed down if there is a lack of local electronic memory. Most modern operating sys-
