The Pentagon () home computer is an enhanced 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 between 1991-1996, making it a widespread ZX Spectrum clone. The name "Pentagon" derives from the shape of the original Pentagon 48 PCB which has a diagonal cut in one of the corners.

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).

thumb|200px|Pentagon-1024SL v2.x

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

References

  • Russian most popular Spectrum models
  • Pentagon 1024 official site
  • Schematic diagram of the Pentagon 48K and drive controller (DjVu)
  • 128K Schematic diagram of the Pentagon (the DjVu)
  • Schematic and wiring diagrams Pentagon 128K 1991, revised and enlarged version (PNG)
  • Wiring diagram 128K the Pentagon (the PNG)
  • NEW English FaceBook Group