<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta http-equiv="X-UA-Compatible" content="IE=edge" />
				<meta name="viewport" content="width=device-width, initial-scale=1" />
		<meta http-equiv="content-type" content="text/html; charset=UTF-8" />
		<meta name="format-detection" content="telephone=no" />
		<meta name="robots" content="noindex" />
			<title>Macintosh: How To Get Serial Driver GPi Signal Access</title><body class="ac-gn-current-support">
	<input type="hidden"  id="cdsHeaderObj" data-json='{"setPod": "true",
"resourceUrl": "https://support.apple.com",
"akamaiUrl": "https://km.support.apple.com",
"modelValue": "Support",
"aiSearchServiceURL": "support.apple.com",
"podLocaleValue": "en_US",
"omnitureLocale": "us_en",
"aiCrossDomainSearchServiceURL": "support-suggestions.apple.com",
"podValue": "us~en",
"searchCountry": "us",
"enableAppleInstant": "yes",
"pageName": "kb",
"amlSuggestionsUrl": "https://www.apple.com/search-services/suggestions/",
"title": "Macintosh: How To Get Serial Driver GPi Signal Access",
"channelName": "LEGACY"
}'>
	<input type="hidden"  id="httpDownloadURL" value="http://support.apple.com">
<!-- 	
 -->

	
<aside id="ac-gn-segmentbar" class="ac-gn-segmentbar" lang="en-US" dir="ltr" data-strings="{ 'exit': 'Exit', 'view': '{%STOREFRONT%} Store Home', 'segments': { 'smb': 'Business Store Home', 'eduInd': 'Education Store Home', 'other': 'Store Home' } }">
</aside>

<h1 id="main-title">Macintosh: How To Get Serial Driver GPi Signal Access</h1>
<div id="abstract">
 
<div id="intro-container"><div class="truncate"><div class="attr SYMPTOMS"><div class="attr TOPIC">As far as I know, the Macintosh serial driver supports checking the status of
the HSKi (CTS) input line but does not support the GPi (DCD) input.
 
With the Macintosh IIfx, developers are encouraged not to deal directly with
the serial port hardware, since the IOP is in the way.  In the past, this was
the only way to use the GPi signal.
 
Has the serial driver been extended to support the GPi signal?  Support for it
is necessary to properly handle high-speed modems.</div></div> <!--  attr Symptom  --></div> <!--  truncate --></div> <!--  intro-container --><div class="clear"> </div>
 </div>   <!-- abstract end -->
<div id="articlecontent">
<div id="indicator-container">      
<div class="indicator archived"></div></div> <!-- Indicator-container -->
  <div class="attr SUMMARY">
The GPi signal is still not supported by the Macintosh serial driver.<BR>
 <BR>
To access the GPi line on a Macintosh IIfx, it is necessary to turn off the<BR>
IOP, as developers have done in the past on other Macintosh systems.  This<BR>
can be done using a control panel, called the &quot;Macintosh IIfx Serial Switch&quot; <BR>
cdev, available from Software Licensing.  Please contact Software Licensing at<BR>
(408) 974-4667 for licensing information.<BR>
<BR>
<BR></div>
</div>


<!-- Start SiteCatalyst code version: H.8. -->


<!-- End SiteCatalyst code version: H.8. -->


<div class="mod-date">Published Date: Feb 18, 2012</div>
  <div id="mimosa-tags">
  
  <input type ="hidden" id="mimosa-tags-heading" value="Related Topics" />
  <input type ="hidden" id="showNavTagFlag" value="true" />
  <input type ="hidden" id="tags-localised" value="Tag" />
        </div>

</div><!--/#content-->
</div><!--/#main-->

<!-- Helpful not helpful section -->
 <div style="display:none">
<div id="meta">
                </div> <!--/#meta-->
</div>          
        <!-- Related Section -->
<div class="border-div"></div>      <!-- Offer Section -->
<div class="border-div"></div>
<div id="promo" style="display:none;"> Still need help?</div>          
         
<div style="clear:both;"></div>

</div>
<input type="hidden"  id="cdsArticleObj" data-json='{"docId": "TA41856",
"cdsLocale": "en_US",
"imgSrc": "",
"akamaiUrl": "https://km.support.apple.com",
"strTitle": "Macintosh: How To Get Serial Driver GPi Signal Access",
"strLocale": "en_US",
"omniturePageName": "acs::kb::dl::ta41856::macintosh: how to get serial driver gpi signal access",
"metaUrl": "",
"baseLink": "https://km.support.apple.com/kb/",
"reportLink": "https://support.apple.com",
"lcl": "en_US",
"localeParam": "en_US",
"viewLocale": "null",
"domainName": "0",
"archive": "true",
"enableAffectedProductPortlet": "false",
"configHeaderFooterLocale": "en_US",
"strCategoryListRefKeys": "",
"lastModifiedDate": "2012-02-18",
"creationDate": "1990-05-15",
"publishedDate": "Sat, 18 Feb 2012 06:10:53 GMT",
"publishedDateHeader": "Sat, 18 Feb 2012 06:10:53 GMT",
"oldInquiraID": "",
"articleNo": "TA41856",
"strChannel": "LEGACY",
"isOmnitureSupported": "true",
"referringPage": "unknown",
"messageResourcesArticleTempEmail": "Email Download Link",
"messageResourcesArticleTempDown": "Download",
"ACStaticText": "{\"more\": \"…more\", \"less\": \"less\" }"
}'>

<div class="footer-wrapper">

</div>


</html>