3.3 COMMERCIAL COMPUTERS

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3.3.1 Mainframes

- Uses a large, and custom designed CPU, in big cabinets

- Large, expensive, and require special housing

- Require specialized personnel to run and program

- Ideal for systems which support many user sharing data and services, such as an accounting system, or database

- Software may be expensive and hard to maintain

- Graphical user interfaces are limited

- Approximate cost > $100,000

- Common example are VAX mainframes

3.3.2 Super Computers

- Completely customized hardware, optimized for numerical (primarily vectored and floating point) calculations

- Suited to huge numerical problems

- Often requires a front-end computer for job queueing, post-processing, and pre-processing

- Tremendous cost > $1,000,000

- One example is the CRAY line of computers

- Often uses parallel and distributed processors, along with nitrogen (or similar) cooling systems

- Very limited spectrum of users

3.3.3 Workstations

- Computers based on leading edge of microprocessor technology, using Enhanced graphical display capabilities.

- These have displaced minicomputers, and created a market for users who have small budgets but need reasonable computer power.

- Run faster than PC's, had better price/performance ratio

- suited to networking, shared disks, and virtual memory

- Perform multiprocessing, thus suited to multiple users.

- Approximate cost $10,000 to $500,000

- Example are SUN, HP, and Silicon Graphics Workstations

- Can often find software intended for mainframes, and for Personal Computers which has been modified to run on Workstations.

- Has the widest collection of public domain software available.

3.3.4 Personal Computers

- Smaller, single user machines based on microprocessors, with some graphics capabilities.

- Very inexpensive from $500 to $10,000

- Some models are Apple Macintosh, IBM PC, etc

- Have very inexpensive software

- Style range such as desk-top, lap-top, factory hardened.

- Have the widest range of commercial software and hardware available.

- Excellent for real time control, and simple user interfaces.

3.3.5 Dedicated Computers

- A number of computers have been built into machines.

- These computers are dedicated to one operation, such as an NC controller, a PLC, A Plastic Injection Machine Controller, computer printer, etc.

- Very well debugged, and easy to use

- Requires some specialized user training.

- Cost is included in cost of equipment, and has effect of lowering costs over relay controlled systems.

- May have simple interfaces for connections to other computers.

3.3.6 Single Board Computers

- A computer with little or no user interface hardware (often only 1 RS-232 port) is provided.

- The previous standard for control.

- Very inexpensive, from $50 to $1000

- Requires Assembly Language Programming

- May come with I/O for digital, analog, serial, or other communication task.

- Hard to implement and debug