almanach mainboard

Mainboard layouts

Mainboard / PC design guides (

A typical mainboard consists of:

Main chipset
I/O Controller (Serial, Parallel, Keyboard, USB, Floppy, ...)
  RTC chips
  port 70h/71h
  port 72h/73h additional 128byte

Dallas Benchmarq Odin  
DS1287     40 Byte RAM
DS1287A     40 Byte RAM + RAM Clear
DS12887 bq3287MT OEC12C887 114 Byte RAM
DS12887A bq3287AMT OEC12C887A 114 Byte RAM + RAM Clear
DS12C887     Y2K

Expansion slots (RAM, Cards, COAST)
CPU socket
HW monitoring
Clock generator
Flash BIOS
  xxx denotes the capacity
  28Fxxx 12v
  29Cxxx 5v
  29LVxxx 3V Flash memory (not often seen)
  28Cxxx EEPROM (like Flash, but needs a special device - Flash works in the motherboard)
  27Cxxx EPROM, so you need UV to erase it and a programmer to rewrite it