How Does a Modem Work?

• Modem Overview
• Analog vs. Digital
• Data Compression
• Error Correction
• Flow Control
• UARTs and Data Buffering

Standards and Protocols

• NEW V.92 White Paper
• NEW V.44 White Paper
• Bell/CCITT/ITU-T Standards
• Data Transfer Protocols
• Fax Standards and Protocols
• Modulation Protocols
• TCP/IP, SLIP, and PPP

Communications and Software issues

• AT Command Sets
• COM Port Settings
• Data Communications Application Software
• IRQ Settings
• S Registers
• Synchronous vs. Asynchronous Data Transfer

Hardware Platforms

CPUs communicate with memory and peripherals by means of a bus. The CPU and memory communicate with each other via a high-speed local bus. However, in most cases, the CPU communicates with graphics cards, peripheral devices, etc. via the I/O bus. The I/O bus, such as the ISA bus, transfers addresses and data among chips in the system. There are platforms available where some cards are accessible by a local rather than an I/O bus.

• ISA, EISA, PCI
• PC Card/PCMCIA
• VESA

Other Devices

• Multimedia Devices
• Voice Modems
• Wireless Data ( PCS, TDMA, CDMA, ARDIS)