Expiring Today—Celebrate National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

outpw/outport

Posted on 1997-01-28
1
Medium Priority
?
726 Views
Last Modified: 2008-03-10
I am attempting to access a card on the ISA bus using Borland C++ 3.1's outpw() and outport() commands, but in both cases the I/O write line goes low (active low) twice while the address is still valid causing the wrong values to be latched because the data is no longer valid on the second strobe. However, that only happens when I attempt to do 16 bit transfers, eight bit transfers work like a charm. Am I doing something wrong or is this simply how the two byte transfer works and I simply have to design around it. Please reply by email.
0
Comment
Question by:robertsb110896
[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
1 Comment
 

Accepted Solution

by:
michaelf earned 100 total points
ID: 1162204
Hi.
Actually it is not about C++ or borland, but
just about ISA bus. ISA bus designed to work
with old style 8-bit devices as well as 16-bit
devices. And I/O device (slave) must tell
CPU (master) wether it is capable to accept /
transmit 16 bit data or just 8 bit.
If it is 8-bit device and program is using
16-bit I/O instructions (using Borland
outpw(), for example) CPU will transfer
data byte by byte: first low order byte
to the specified port, then high order
byte to the port with address greater by
one. I believe it is your case.

If you want to receve 16 bit of data
at once, you have to assert special
signal that tells that it is 16-bit
slave device. I do not have ISA bus
description with me, but according
to the brief table I do have it is
"I/O 16 chip select : D2". You have to
check it using complete ISA bus
description.
  Regards,
      MichaelF

0

Featured Post

On Demand Webinar: Networking for the Cloud Era

Ready to improve network connectivity? Watch this webinar to learn how SD-WANs and a one-click instant connect tool can boost provisions, deployment, and management of your cloud connection.

Question has a verified solution.

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

When writing generic code, using template meta-programming techniques, it is sometimes useful to know if a type is convertible to another type. A good example of when this might be is if you are writing diagnostic instrumentation for code to generat…
Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilation…
The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.
The viewer will be introduced to the member functions push_back and pop_back of the vector class. The video will teach the difference between the two as well as how to use each one along with its functionality.

730 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