PGA ProcessorThe Motorola 68020 is a 32-bit microprocessor from Motorola, released in 1984. It is the successor to the Motorola 68010 and is succeeded by the Motorola 68030.
The 68020 (usually just referred to as the '020, pronounced oh-two-oh or oh-twenty) had 32-bit internal and external data and address buses. A lower cost version, the 68EC020, only had a 24-bit address bus. The 68020 was produced at speeds ranging from 12 MHz to 33 MHz.
Improvements over 68010
The 68020 added many improvements to the 68010 including a 32-bit arithmetic logic unit (ALU), external data bus and address bus, and new instructions and addressing modes. The 68020 (and 68030) had a proper three-stage pipeline.
The alignment restriction on word and longword data access present in its predecessors was removed with the 68020.
Multiprocessing features
The Motorola multiprocessing model was added with the 68020. This allowed up to eight processors per system to co-operate, these eight could be any number of CPUs, FPUs but a single MMU (either a Motorola 68841 or 68851). This had some limitation, as each CPU used had to be the same model (not necessarily the same clock) and each FPU has to be the same model (again, not necessarily the same clock) so multiprocessing a 68020/25 with a 68030/25 was not allowed (the 020, for example, could not be aware of the 030's internal MMU) but a 68020/25 with a 68882/33 was perfectly acceptable and quite common. It was, however, extremely uncommon to see more than one CPU or FPU in the same system. Most Unix boxes made with 68020s were simply the '020, an FPU (68881 or 68882) and an MMU (68841 or 68851).
The new instructions included some minor improvements and extensions to the supervisor state, several instructions for software management of a multiprocessing system (which were removed in the 68060), some support for high-level languages which did not get used much (and was removed from future 680x0 processors), bigger multiply (32×32→64 bits) and divide (64÷32→32 bits quotient and 32 bits remainder) instructions, and bit field manipulations.
Addressing modes
The new addressing modes added scaled indexing and another level of indirection to many of the pre-existing modes, and added quite a bit of flexibility to various indexing modes and operations. Though it was not intended, these new modes made the 68020 very suitable for page printing; most laser printers in the early '90s had a 68EC020 at their core.
The 68020 had a minimal 256 byte direct-mapped instruction cache, arranged as 64 four-byte entries. Although small, it still made a significant difference in the performance of many applications. The resulting decrease in bus traffic was particularly important in systems relying heavily on DMA.
Usage
The 68020 was used in the Apple Macintosh II and Macintosh LC personal computers, as well as Sun 3 workstations and the Hewlett Packard 8711 Series Network Analyzers. The Commodore Amiga 1200 computer and the Amiga CD32 games console used the cost-reduced 68EC020.
It is also the processor used on board TGV trains to decode signalling information which is sent to the trains through the rails, and is the CPU of the computers in the Eurofighter Typhoon.
For more information on the instructions and architecture see Motorola 68000.
The LGA is used as a physical interface for microprocessors of the Intel Pentium 4 and AMD Opteron families. Unlike the pin grid array (PGA) interface found on most AMD and Intel processors, there are no pins on the chip; in place of the pins are pads of bare gold-plated copper that touch pins on the motherboard.
LGA processor sockets include Socket F (also called Socket 1207) from AMD[1] and the Prescott core Pentium 4 and Xeon chip systems with the new model number system from Intel.
The Intel desktop LGA socket is dubbed Socket 775 or Socket T while the server variant is dubbed Socket J or Socket 771. Intel supposedly decided to switch to an LGA socket because it provides a larger contact point, allowing, for example, higher clock frequencies. The LGA setup provides higher pin densities, allowing more power contacts and thus a more stable power supply to the chip. Motherboard vendors have complained that LGA packaging was introduced solely to move the burden of bent pin problems from Intel to the electronics vendors.[citation needed]
Similar to Intel, AMD decided to use an LGA socket because it allows higher pin densities. The required size of a 1207-pin PGA would simply be too large and would consume too much space on motherboards.
Intel released its new LGA format processors in June 2004 and recently displayed plans to transition its Xeon processors to LGAs. AMD released its Socket F LGA Opteron in 2nd quarter 2006.
Casing System
Introduction
This document is written for professional system integrators building PCs from industry-accepted motherboards, chassis, and peripherals. It provides information and recommendations for thermal management in desktop systems using boxed Intel® Pentium® III, Pentium® II processors, and Celeron® processors. (The term "boxed processors" refers to processors packaged for use by system integrators.)
It is assumed that the reader has a general knowledge of and experience with desktop PC operation, integration, and thermal management. Integrators who follow the recommendations presented here can provide their customers with more reliable PCs and will see fewer customers returning with problems.
Thermal Management
Systems using boxed processors all require thermal management. The term "thermal management" refers to two major elements: a heatsink properly mounted to the processor, and effective airflow through the system chassis. The ultimate goal of thermal management is to keep the processor at or below its maximum operating temperature.
Proper thermal management is achieved when heat is transferred from the processor to the system air, which is then vented out of the system. Desktop boxed processors are shipped with a high-quality fan heatsink, which can effectively transfer processor heat to the system air. It is the responsibility of the system integrator to ensure adequate system airflow.
This document makes recommendations for achieving good system airflow and provides suggestions for improving the effectiveness of a system's thermal management solution.
Fan Heatsink
Boxed processors are shipped in several processor packages;
the Single Edge Contact Cartridge (S.E.C.C.)
the Single Edge Contact Cartridge 2 (S.E.C.C.2)
the Single Edge Processor Package (S.E.P.P.)
and the Plastic Pin Grid Array (PPGA)
All boxed processors for desktop systems are shipped with a fan heatsink and fan power cable. These items should be used following the directions contained within the boxed processor installation notes included in the processor box. Thermal interface material (already applied) provides effective heat transfer from the processor to the fan heatsink. S.E.C.C., S.E.C.C.2, and S.E.P.P. boxed processors ship with an attached fan heatsink with the thermal interface material included between the processor and the fan heatsink. Current PPGA boxed processors ship with an unattached fan heatsink that includes thermal interface material on the fan heatsink base and a fan cable incorporated into the fan. The fan cable provides power to the fan by connecting to a motherboard-mounted power header. Some boxed processor fan heatsinks provide fan speed information to the motherboard. (Only motherboards with hardware monitoring circuitry can use the fan speed signal.)
Boxed processors use high-quality ball-bearing fans that provide a good local air stream. This local air stream transfers heat from the heatsink to the air inside the system. However, moving heat to the system air is only half the task. Sufficient system airflow is also needed in order to exhaust the air. Without a steady stream of air through the system, the fan heatsink will re-circulate warm air, and therefore may not cool the processor adequately.
System Airflow
System airflow is determined by:
Chassis design
Chassis size
Location of chassis air intake and exhaust vents
Power supply fan capacity and venting
Location of the processor slot(s)
Placement of add-in cards and cables
System integrators must ensure airflow through the system to allow the fan heatsink to work effectively. Proper attention to airflow when selecting subassemblies and building PCs is important for good thermal management and reliable system operation.
Integrators use three basic chassis form factors for desktop systems: ATX, microATX, and the older Baby AT form factor.
In systems using Baby AT components, airflow is usually from front to back. Air enters the chassis from vents at the front and is drawn through the chassis by the power supply fan. The power supply fan exhausts the air through the back of the chassis. Figure 1 and Figure 2 show the airflow through Baby AT systems.
Figure 1. System Airflow Through Baby AT Desktop Chassis (Top View)
Figure 2. System Airflow Through Baby AT Tower Chassis (Side View)
Intel recommends the use of ATX and microATX form factor motherboards and chassis for boxed processors. The ATX and microATX form factors simplify assembly and upgrading of desktop systems, while improving the consistency of airflow to the processor.
With regard to thermal management, ATX components differ from Baby AT components in that the processor is located close to the power supply, rather than to the front panel of the chassis. Power supplies that blow air out of the chassis provide proper airflow for active fan heatsinks. The boxed processor's active fan heatsink cools the processor more effectively when combined with an exhausting power supply fan. Because of this, the airflow in systems using the boxed processor should flow from the front of the chassis, directly across the motherboard and processor, and out of the power supply exhaust vents. Figure 3 shows proper airflow through an ATX system to achieve the most effective cooling for a boxed processor with an active fan heatsink. For boxed processors, chassis that conform to the ATX Specification Revision 2.01 or later are highly recommended. For more information on the ATX form factor, and a list of ATX chassis manufacturers, please visit the ATX web site †.
Figure 3. System Airflow Through ATX Tower Chassis Optimized For the Boxed Processor With an Active Fan Heatsink
One of the ways microATX chassis differ from ATX chassis is that the power supply location and type may vary. Thermal management improvements that apply to ATX chassis will also apply to microATX. For more information on the microATX form factor, and a list of microATX chassis manufacturers, please visit the microATX website †.
The following is a list of guidelines to be used when integrating a system. Specific mention of Baby AT, ATX, or microATX components is made where necessary.
Cooling system
Introduction
This document is written for professional system integrators building PCs from industry-accepted motherboards, chassis, and peripherals. It provides information and recommendations for thermal testing on systems using desktop boxed processors.
Thermal testing should be done on new system configurations built with boxed processors. Two evaluation methods are detailed here that apply to several desktop boxed processors. Each boxed processor has a thermal management application note that has specific information pertinent to the processor. Together, the specific boxed processor thermal management application note and this document will enable a system integrator to thermally evaluate a system configuration. A third document entitled System Thermal Management for Boxed Intel Processor-Based Desktop PCs has information about building systems with quality thermal management and improving thermal management in systems that have insufficient airflow.
Thermal Management
Systems using boxed processors all require thermal management. The term "thermal management" refers to two major elements: a heatsink properly mounted to the processor, and effective airflow through the system chassis. The ultimate goal of thermal management is to keep the processor at or below its maximum operating temperature.
Proper thermal management is achieved when heat is transferred from the processor to the system air, which is then vented out of the system. Boxed processors are shipped with a high-quality fan heatsink, which can effectively transfer processor heat to the system air. It is the responsibility of the system integrator to ensure adequate system airflow.
This document provides procedures for determining the effectiveness of a system's thermal management solution. The temperature specifications for Intel processors are documented in the processor datasheets that are available from the developer's website. A thermal metrology is also documented for each processor. The metrology describes how to properly test the processor to ensure that the processor never exceeds its maximum specified temperature. Most thermal metrologies for current processors require drilling heatsinks, soldering wires to baseboards, and the purchase of outside equipment. This document details two methods for evaluating the representative system's thermal management. These evaluations do not validate that the processor specification will never be exceeded, but can provide confidence in the system's ability to provide the proper internal environment for the boxed processor.
Before testing the system, it is important to evaluate the conditions that the system will operate under. An important condition to consider is the maximum ambient temperature that the system will be specified to operate under. Many large Original Equipment Manufacturers (OEMs) specify the maximum ambient temperature specification to be 35°C (95°F). In areas without air conditioning, 40°C (104°C) may be more appropriate. System integrators should choose a value that is appropriate for their customers and specify that maximum operating temperature to the customer.
Integrated Fan Heatsink
Boxed processors are shipped with a fan heatsink and fan power cable. These items should be used following the directions in the installation notes shipped with the boxed processor box. Below are drawings of the desktop boxed processor in each of the processor packages.
Plastic Pin Grid Array (PPGA)
Single Edge Processor Package (S.E.P.P.)
Fans used on boxed processors are high-quality ball bearing fans that provide a good local air stream. This local air stream transfers heat from the heatsink to the air inside the system. However, moving heat to the system air is only half the task. Sufficient system airflow is also needed to exhaust the air. Without a steady stream of air through the system, the fan heatsink will re-circulate warm air, and therefore may not cool the processor adequately.
A common feature on all desktop boxed processors is the fan inlet. This circular area on each heatsink has a hologram in the center, and openings that allow air to flow into the fan center and out the sides of the fan heatsink. The temperature of the air entering the fan inlet is a critical factor in cooling the boxed processor. Measuring the temperature of the air entering the fan inlet can determine if the boxed processor fan heatsink is able keep the processor temperature within its operating range. To determine the recommended maximum ambient air temperature for a specific processor, see the thermal management document for that specific product.
The boxed processor fan heatsinks all have metal bases that allow for quick heat transfer. The temperature of the heatsink base at a specified location can also be used to determine if the boxed processor fan heatsink is able to keep the processor within specification. Since the processor heatsink geometry changes as the form factor varies, the exact location of the test point will be documented in the thermal management application note for the specific processor.
Latest Buses
PCI Express Connector Manufacturers
PCIe uses 4 different sizes of connector, all of which are card-edge type to accept a PCI Express card using card-edge fingers spaced on a 1.00mm pitch [0.394 inches]. The 1x size is the smallest with 36 contact positions. The x4 uses 64 contacts, the x8 uses 98 contacts, and the x16 has 164 contact positions. The nominal height of the connector above the PWB is 11mm. The width of the 1x and 16x connector is 8.70mm as shown below, how ever the 1x graphic is shown slightly larger.
Introduction
The processor communicates with other peripherals in the PC through a path of data called bus. Since the release of the first PC, in 1981, up to the present day, several types of bus have been developed in order to allow the communication between the processor and input and output peripherals. We can name the following buses already launched:
=>ISA
=>EISA
=>MCA
=>VLB
=>PCI
=>AGP
PCI Express
The main difference among the several types of bus is in the number of bits that can be transmitted at a time, and in the operating frequency used. Nowadays the two fastest types of PC expansion bus are the PCI and the AGP. We listed the transfer rate of those buses in the chart below. The PCI-X bus is an extension of the PCI bus designed to the market of network servers.
The PCI bus was released by Intel in June, 1992. Since then, almost all PC expansion peripherals, such as hard disks, sound cards, LAN cards, and video cards have been using the PCI bus. The thing is, the PCI bus maximum transfer rate - 133 MB/s – proved to be insufficient for modern 3D applications and it represented a limitation to the development of more sophisticated video cards. In order to solve that issue, Intel created a new bus, called AGP, to increase the transfer rate of video cards – now they wouldn’t have to be installed in the PCI bus anymore, but in the AGP bus, which is faster. Then the PCI was not so “busy” anymore, since video cards were the great responsible for the intense traffic in the PCI bus.
