?
Solved

ps2 keyboard port maximum data rate?

Posted on 2011-09-13
5
Medium Priority
?
562 Views
Last Modified: 2012-05-12
I'm programming a hardware keyboard wedge and wondering about the data rate. What maximum data rate might I expect from a desktop's ps2 keyboard port?
0
Comment
Question by:FuturesTrader
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
5 Comments
 
LVL 3

Expert Comment

by:inetman
ID: 36533412
keystrokes per minute is the number your looking for. So 255 should be a good size, as I do not know of anyone that types that many keys per second. normal people type 30-60 wpm. I can do slightly better.. so if you set your buffer to that size it should work great.
0
 
LVL 84

Expert Comment

by:Dave Baldwin
ID: 36533424
This page looks like it has the info: http://www.computer-engineering.org/ps2protocol/  Note the variable clock rate, 10-16.7KHz.
0
 

Author Comment

by:FuturesTrader
ID: 36533515
would a safe assumption be that a 10khz clock rate translates to a single character worst case delay of ~100 microsecs?
0
 

Author Comment

by:FuturesTrader
ID: 36533522
hmmm... actually a worst case delay would occur when the character arrived at the port at exactly the worst time in the clock cycle.. or if the clock is generated in the keyboard the character would be sent at that time. Either way would the worst case single character delay be about 200microsecs?
0
 
LVL 84

Accepted Solution

by:
Dave Baldwin earned 2000 total points
ID: 36533576
No, that interface is much slower than that.  10KHz data rate at 11 bits per character is only 900 bytes per second.  But this is a bidirectional interface and the controller in the computer can take over and send status bytes back to the keyboard.  Or worse yet, interrupt the current transmission and require it to be resent.  Since PS2 was a keyboard or mouse interface, speed was not considered to be an issue.
0

Featured Post

Enroll in August's Course of the Month

August's CompTIA IT Fundamentals course includes 19 hours of basic computer principle modules and prepares you for the certification exam. It's free for Premium Members, Team Accounts, and Qualified Experts!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

System overheating may become a serious problem if not taken care of at the proper time. I am writing this article because I faced a similar problem. Intro All electronic devices produce heat, but computers are a special case - the processors bo…
More and more people are using the enhanced small form-factor pluggable (SFP+) tranceivers, and speed is of utmost importance. Testing of speeds are critical to ensure that the devices will meet the speed requirements. There are some testing challen…
Finding and deleting duplicate (picture) files can be a time consuming task. My wife and I, our three kids and their families all share one dilemma: Managing our pictures. Between desktops, laptops, phones, tablets, and cameras; over the last decade…
Add bar graphs to Access queries using Unicode block characters. Graphs appear on every record in the color you want. Give life to numbers. Hopes this gives you ideas on visualizing your data in new ways ~ Create a calculated field in a query: …

765 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question