Pentagon (computer)
# Pentagon (computer)

The Pentagon (ru: Пентагон) home computer was a clone of the British-made Sinclair ZX Spectrum 128. It was manufactured by amateurs in the former Soviet Union, following freely distributable documentation. Its PCB 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 possibilities such as Covox (usually named as SounDrive) or DMA UltraSound
* Additional video modes: 512x192 monochrome, 384x304, 256x192x15 (with no Attribute clash)
* CMOS with persistent real-time clock
* IDE Controller for hard drives
* "Turbo Mode" that clocks the CPU up to 7 MHz
