{"id":11219,"date":"2015-10-01T22:08:20","date_gmt":"2015-10-02T02:08:20","guid":{"rendered":"http:\/\/www.megalextoria.com\/wordpress\/?p=11219"},"modified":"2017-05-12T09:59:07","modified_gmt":"2017-05-12T13:59:07","slug":"commodore-128","status":"publish","type":"post","link":"https:\/\/www.megalextoria.com\/wordpress\/index.php\/2015\/10\/01\/commodore-128\/","title":{"rendered":"Commodore 128"},"content":{"rendered":"

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The Commodore 128<\/b>, also known as the C128<\/b>, C-128, C=128, or occasionally CBM 128, is the last 8-bit<\/b> home computer that was commercially released by Commodore Business Machines<\/b> (CBM<\/b>). Introduced in January 1985 <\/b>at the CES<\/b> in Las Vegas<\/b>, it appeared three years after its predecessor, the bestselling Commodore 64<\/b>.<\/p>\n

The C128<\/b> is a significantly expanded successor to the C64<\/b>, with nearly full compatibility<\/b>. The new machine has 128 kB<\/b> of RAM in two 64 kB banks<\/b>, and an 80-column<\/b> color video output. It has a redesigned case and keyboard. Also included is a Zilog Z80<\/b> CPU which allows the C128 to run CP\/M<\/b>, as an alternative to the usual Commodore BASIC<\/b> environment. The presence of the Z80<\/b> and the huge CP\/M<\/b> software library it brings, coupled with the C64\u2019s software library, gives the C128<\/b> one of the broadest<\/b> ranges of available software among its competitors.<\/p>\n

The primary hardware designer of the C128 was Bil Herd<\/b>, who had worked on the Plus\/4<\/b>. Other hardware engineers were Dave Haynie<\/b> and Frank Palaia<\/b>, while the IC design work was done by Dave DiOrio<\/b>. The main Commodore system software was developed by Fred Bowen<\/b> and Terry Ryan<\/b>, while the CP\/M subsystem was developed by Von Ertwine<\/b>.<\/p>\n

The C128<\/b>\u2019s keyboard includes four cursor keys<\/b>, an Alt key<\/b>, Help key<\/b>, Esc key<\/b>, Tab key<\/b> and a numeric keypad<\/b>. None<\/b> of these were present on the C64<\/b>. Many of the added keys<\/b> match ones present on the IBM PC<\/b>\u2019s keyboard and made the new computer more attractive<\/b> to business software developers. Instead of the single 6510<\/b> microprocessor of the C64, the C128 incorporated a two-CPU design<\/b>. The primary CPU, the 8502<\/b>, is a slightly improved version of the 6510 capable of being clocked at 2 MHz<\/b>. The second CPU is a Zilog Z80<\/b>which is used to run CP\/M<\/b> software.<\/p>\n

The C128<\/b> has three operating modes. C128 Mode<\/b> (native mode) ran at 1 or 2 MHz with the 8502 CPU and had both 40- and 80-column text modes available. CP\/M Mode<\/b> uses both the Z80<\/b> and the 8502<\/b> and is able to function in both 40- or 80-column text mode. C64 Mode<\/b> is nearly 100 percent compatible with the earlier computer. Selection of these modes is implemented via the Z80 chip<\/b>. The Z80 controls the bus on initial boot-up and checked to see if there is a CP\/M<\/b> disk in the drive, if there are any C64\/C128<\/b> cartridges present, and if the Commodore key (C64-mode selector) is active on boot-up. Based on what it finds, it will switch<\/b> to the appropriate mode of operation.<\/p>\n

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