PC 20-III/S

Serial: 093705

Looks like an ordinary PC 20-III. But what does the “/S” mean?

• mainboard revision: 5.7
• CPU: Siemens 8088 running at 4.77MHz (Standard), 7.16Mhz (Turbo), or 9.54MHz (Double)
• FPU: Intel C8087 Ceramic math co-processor
• RAM: 640KB
• ROM: 32KB Phoenix self-configuring BIOS Version 4.36
• Chipset: Faraday FE2010A single chip controller IC
• Clock: Battery-backed Real Time Clock (RTC) maintains the date and time while the system is powered off
• Floppy Drive:
  • A:\ 360K 5.25″ Chinon FZ-502
• Hard disk: missing
• Sound: On-board piezoelectric beeper
• Ports:
  • 9-pin d-sub bus mouse port compatible with Commodore Amiga 1352 mouse (MOS 5720)
  • 25-pin d-sub RS-232 serial port (Western Digital WD8250-PL)
  • 25-pin d-sub 8-bit Centronics parallel port (Paradise PPC1)
  • DIN-5 IBM PC XT-compatible keyboard port
  • 9-pin d-sub RGBI/Monochrome video port
  • RCA composite video port
• Video: Onboard Paradise PVC4
  • MDA Monochrome Text
  • Hercules Monochrome Graphics
  • CGA Color Text and Graphics
  • Plantronics Colorplus Graphics
  • Alpha132 Monochrome Text
• 3x 8-bit ISA slots for expansion
• 75 watt power supply

• work performed:
  • battery removed, all neutralized and cleaned
  • FDDs disassembled, cleaned and lubricated
  • whole machine completely dismantled and cleaned
  • missing reset button cap added
  • missing motherboard stand replaced
  • mainboard and PSU recapped with Rubycon brand 105° type
  • slot covers restored/de-rusted
  • damaged video DIP switch replaced