Xi8088 Version 2.0
Introduction
Xi 8088 IBM PC/XT compatible processor board. 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.
Proposed Improvements
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 of the load capacitors C1 and C2 is (Load Capacitance of the Crystal – Capacitance of the IC and PCB) x 2
For a crystal with load capacitance of 20pf (find in datasheet) and board and chip with built-in 5pf capacitance then the capacitors you should use will be around 30pf. But since capacitors have different tolerances and measuring such small capacitances is hard with shitty equipment then experimenting with different value capacitors is your best bet.
