3.3 COMMERCIAL COMPUTERS
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
