The Sega Genesis Nomad was a north American exclusive handheld Mega Drive that was released in October of 1995. The console features a 3.25″ backlit display, a 6 button controller setup, additional controller port for multiplayer gaming and an AV output to allow the console to connect to a television set. The Nomad can be powered with 6 AA batteries, a battery recharger called the Genesis Nomad PowerBack or a traditional Mega Drive AC adapter. Like the Game Gear, the Nomad suffers from poor battery life (2-3 hours) and a screen that suffers from extreme ghosting when games scroll quickly.

As the only in-house SEGA-developed portable Mega Drive system, the Genesis Nomad has become a collector’s item. Due to the late release of the system and its high price point (originally releasing for $179), the Genesis Nomad was not a success with only an estimated 1 million units sold during its lifespan.

The backside of the nomad, with the extra controller port, the headphone connector, and volume dial showing.

THe SN76489 Digital Complex Sound Generator (DCSG) is a TTL compatible programmable sound generator chip created by Texas Instruments. It main application was the generation of music and sound effects in home computers, arcade machines and home game consoles. Functionally the chip was similar to the General Instrument AY-3-8910.

SOund Capabilities:

• 3 Square Wave tone generators, 16 volume levels
• 1 White Noise Generator (white and periodic noice, 3 frequencies, 16 volumes)

The SN76489 Was originally designed to be used in the TI-99/4 computer, where it was first called the TMS9919 and later SN94624, and had a 500 kHz max clock input rate. Later, when it was sold outside of TI, it was renamed the SN76489, and a divide-by-8 was added to its clock input, increasing the max clock input rate to 4 MHz, to facilitate sharing a crystal for both NTSC colorburst and clocking the sound chip. A version of the chip without the divide-by-8 input was also sold outside of TI as the SN76494, which has a 500 kHz max clock input rate.

The Motorola 68000 is a 16/32-bit microprocessor that was first released in 1979. It was widely used in computers and other electronic devices during the 1980s and early 1990s. The 68000 was known for its advanced architecture, which included a 32-bit internal bus and a 24-bit address bus, allowing it to access up to 16 megabytes of memory. This made it more powerful than many other processors of its time, such as the Intel 8086 and Zilog Z80. It was also designed to be highly modular and expandable, with a large number of on-chip and off-chip peripherals.

Some of the most famous and successful computers that used the 68000 was the Commodore Amiga and the Atari ST, both of which were popular in the home and personal computer markets. Additionally, it was also used in workstations, such as the Sun 3 and Apollo DN3000, and in a wide variety of embedded systems and industrial control systems. The 68000 was also used in the Macintosh, the first model of the Macintosh was powered by a Motorola 68000 CPU. The processor was eventually succeeded by the 68020 and 68030, which offered improved performance and additional features.

The 68000 has a 32-bit instruction set, with 32-bit registers and a 16-bit internal data bus. The address bus is 24-bit and does not use memory segmentation, making it easier to address memory. There are three ALU's (Arithmetic Logic Unit), two for calculating addresses, and one for data, and the chip has a 16-bit external address bus.

The 68000 architecture was expanded with 32-bit ALUs, and caches. Here is a list with some 680x0 versions and their major improvements:

• 68010 - Virtual memory support
• 68020 - 32-bit ALU & Instruction Cache
• 68030 - On-Chip MMU, 2x 256 byte cache
• 68040 - 2x 4K Cache, 6 stage pipeline, FPU
• 68LC040 - No Floating Point Unit (FPU)
• 68060 - 2x 8K Cache, 10 stage pipelinet

Source: WikiPedia - Motorola 6800
Source: WikiPedia - 68000 Series