6502.org Forum Projects Code Documents Tools Forum
It is currently Sun Nov 24, 2024 11:24 am

View unanswered posts | View active topics


Board index » 6502.org Users Forum » Hardware

All times are UTC




Post new topic Reply to topic  Page 1 of 1
  [ 4 posts ] 
  Previous topic | Next topic 
Author Message
Dan Moos
 Post subject: 65c22 question.
PostPosted: Sun Dec 13, 2020 7:01 pm 
Offline

Joined: Sat Mar 11, 2017 1:56 am
Posts: 276
Location: Lynden, WA
If I have a particular interrupt disabled in the IER, will it still set the appropriate flag in the interrupt flag register?

Basically, I want the 6502 to be able to get the status of a handshake line (I want to know when the peripheral device signals DATA TAKEN). I don't want the 6502 to be interrupted for this. I just want to read the flag register.

This seems like it would be a common requirement. I'm not able to try this at the moment (I'm away from the hardware). Just curious if that's how it works.
Top
 Profile  
Reply with quote  
Chromatix
 Post subject: Re: 65c22 question.
PostPosted: Sun Dec 13, 2020 7:52 pm 
Offline

Joined: Mon May 21, 2018 8:09 pm
Posts: 1462
Section 2.3:

When the Data Ready signal is received, it sets an internal flag in the Interrupt Flag Register (IFR). This flag may interrupt the microprocessor or it may be polled under program control.

This indicates to me that, in general, the IFR operates independently of the IER, and the latter simply acts as a mask between the IFR and the /IRQ output.
Top
 Profile  
Reply with quote  
Dan Moos
 Post subject: Re: 65c22 question.
PostPosted: Sun Dec 13, 2020 8:02 pm 
Offline

Joined: Sat Mar 11, 2017 1:56 am
Posts: 276
Location: Lynden, WA
I missed that line. Seems to perfectly describe what I need. Thanks!
Top
 Profile  
Reply with quote  
GARTHWILSON
 Post subject: Re: 65c22 question.
PostPosted: Sun Dec 13, 2020 8:03 pm 
Offline
User avatar

Joined: Fri Aug 30, 2002 1:09 am
Posts: 8546
Location: Southern California
Yes; from section 1.14 of the data sheet:
Quote:
If an Interrupt Flag is a Logic 1, and the corresponding Interrupt Enable bit is a Logic 1, the IRQB will go to a Logic 0.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?
Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  Page 1 of 1
  [ 4 posts ] 

Board index » 6502.org Users Forum » Hardware

All times are UTC


Who is online

Users browsing this forum: No registered users and 44 guests

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
6502.org is an ongoing project by Mike Naberezny and contributors.