This is a old article that i forgot to publish.
The Commodore 128 (C128, CBM 128, C=128) home computer was the last 8-bit machine commercially released by Commodore Business Machines (CBM). Introduced in January 1985 at the CES in Las Vegas, it appeared three years after its predecessor, the bestselling Commodore 64.
The C128 was a significantly expanded successor to the C64, with nearly full compatiblity. The new machine had 128 kB of RAM in two 64 kB banks, and an 80-column color video output. It had a redesigned case and keyboard. Also included was a Zilog Z80 CPU which allowed the C128 to run CP/M, as an alternative to the usual Commodore BASIC environment. The presence of the Z80 and the huge CP/M software library it brought, coupled with the C64′s software library, gave the C128 one of the broadest ranges of available software among its competitors.
The primary hardware designer of the C128 was Bil Herd, who had worked on the Plus/4. Other hardware engineers were Dave Haynie and Frank Palaia, while the IC design work was done by Dave DiOrio. The main Commodore system software was developed by Fred Bowen and Terry Ryan, while the CP/M subsystem was developed by Von Ertwine.
The C128′s keyboard included four cursor keys (previous Commodores had two, which required using the shift key to move the cursor up or left. These were retained on the 128, for C64 compatibility), an Alt key, Help key, Esc key, Tab key (not present on prior models) and a numeric keypad. The lack of a numeric keypad, Alt key and Esc key on the C-64 were an issue with some CP/M productivity software when used with the 64′s Z-80 cartridge.
Many of the added keys matched ones present on the IBM PC’s keyboard. While the 128′s 40 column mode closely duplicated that of the C64, an extra 1K of color RAM was made available to the programmer, as it was multiplexed through memory address 1. The 128′s power supply was improved over the 64′s unreliable design, being much larger and equipped with cooling vents and a replaceable fuse. Instead of the single 6510 microprocessor of the C64, the C128 incorporated a two-CPU design. The primary CPU, the 8502, was a slightly improved version of the 6510 capable of being clocked at 2 MHz. The second CPU was a Zilog Z80 which was used to run CP/M software, as well as to initiate operating mode selection at boot time. The two processors could not run concurrently, thus the C128 was not a multiprocessing system.