Xi8088 Version 2.0
Introduction
Xi 8088 IBM PC/XT compatible processor board.
Contributions Welcome
If anyone reading this page is interested in contributing content please send me a text message at 3476042083 with your email address and I will send instructions on how to setup an account.
Features
- ISA board form factor
- Support of PS/2 keyboard and mouse
- Built-in real time clock with NVRAM
Board Layout
Click on any chip for more information. Most of the chips below lead to blank pages. I am looking for help in populating them with some info. I know datasheets are available however it would be nice to have a brief summary of each component and what is does overall on this board.
Troubleshooting
Non-Turbo clock is unstable or non existent
Sometimes the non-turbo crystal fails to oscillate. The proposed improvement to this circuit is seen below. I will test it further and introduce this change in the next revision of the board. Roughly speaking the formula to determine the values based on the Load capacitance of the crystal is Cload = c^2/(2c)
For a crystal with load capacitance of 20pf (find in datasheet) then the capacitors you should add up to 40pf. But since capacitors have different tolerances and measuring such small capacitances is hard with cheap equipment then experimenting with different value capacitors is your best bet. Remember that capacitors in parallel add capacitance Cp = c1 + c2... and series they are 1/Cs = 1/c1 + 1/c2 ...
