The Pentagon (Пентагон) home computer was a clone of the British-made Sinclair

ZX Spectrum 128 The ZX Spectrum () is an 8-bit home computer that was developed by Sinclair Research. It was released in the United Kingdom on 23 April 1982, and became Britain's best-selling microcomputer. Referred to during development as the ''ZX81 Colour ...

. It was manufactured by amateurs in the former

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

, following freely distributable documentation. Its

PCB PCB may refer to: Science and technology * Polychlorinated biphenyl, an organic chlorine compound, now recognized as an environmental toxin and classified as a persistent organic pollutant * Printed circuit board, a board used in electronics * ...

was copied all over the ex-USSR in 1991-1996, which made it a widespread ZX Spectrum clone. The name "Pentagon" derives from the shape of the original PCB (Pentagon 48), with a diagonal cut in one of the corners. Many simple devices (upgrades) were invented to connect to the Pentagon with some soldering.

Versions

*Pentagon 48K (1989 by Vladimir Drozdov) *Pentagon 128K (1991) *Pentagon 128K 2+ (1991 by ATM) *Pentagon 128K 3+ (1993 by Solon) *Pentagon 1024SL v1.x (2005 by Alex Zhabin) *Pentagon-1024SL v2.x (2006 by Alex Zhabin) *Pentagon ver.2.666 (2009 by Alex Zhabin) The Pentagon 1024SL v2.3 included most of the upgrades of the standard Spectrum architecture, including 1024 KB RAM, Beta 128 Disk Interface and ZX-BUS slots (especially for IDE and General Sound cards). This model also featured a "turbo" mode (7 MHz instead of the original's 3.50 MHz).

Upgrades from the original ZX Spectrum

* Extra RAM ranging from 256 KB to 4 MB * Several

sound card A sound card (also known as an audio card) is an internal expansion card that provides input and output of audio signals to and from a computer under the control of computer programs. The term ''sound card'' is also applied to external au ...

possibilities such as

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