title: Pentagon (computer)
text: # 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
  