Pentagon (computer)

The Pentagon (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. ^[1]

Many simple devices (upgrades) were invented to connect to the Pentagon with a soldering iron.^[2]

Versions^[3]

• 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)^[4]

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).

Pentagon-1024SL v2.x

Upgrades from the original ZX Spectrum

• Extra RAM ranging from 256 KB to 4 MB
• Several soundboard possibilities such as Covox, SounDrive or DMA UltraSound
• additional video modes: 512x192 monochrome, 384x304, 256x192x15 (without using attributes)
• CMOS with persistent real-time clock
• IDE Controller for hard drives
• "Turbo Mode" that clocks the CPU up to 7 MHz

References

External links

• Russian most popular Spectrum models
• Pentagon 1024 official site (Russian)
• 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)

Sinclair computers, derivatives, and clones (ZX80/81, ZX Spectrum, and QL clones)
Sinclair Research / Science of Cambridge	MK14 ZX80 ZX81 ZX Spectrum (ZX Spectrum+, ZX Spectrum 128) QL
Timex Corporation	TS 1000 TS 1500 TS 2068 TC 2048 TC 2068 Komputer 2086
Amstrad	ZX Spectrum +2 ZX Spectrum +3
Cambridge Computer	Z88
Compatible or related systems	ATM MicroAce Jupiter Ace SAM Coupé Didaktik Dubna 48K Hobbit Pentagon Scorpion Sprinter One Per Desk CST Thor Q40/Q60 TK82C TK85 TK90X TK95
Sinclair Research peripherals	ZX Printer ZX Interface 1 ZX Interface 2 ZX Microdrive
Timex peripherals	TS2040 Printer TS2050 Modem FDD Disk Drive FDD3000 Disk Drive