Comments on: Understanding how the “code switching” EPROM circuit works http://www.iroczone.com/2009/10/understanding-how-the-code-switching-eprom-circuit-works/ IROC-Z Forums, Photos, Videos, History, Information, and more. Thu, 12 Jan 2012 01:02:45 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Cliff Harris http://www.iroczone.com/2009/10/understanding-how-the-code-switching-eprom-circuit-works/comment-page-1/#comment-270 Cliff Harris Thu, 18 Aug 2011 10:27:18 +0000 http://www.iroczone.com/?p=71#comment-270 When you turn on the ignition switch, there is a chip in the ECM that holds the CPU in reset until the power is stable.  The switch/pullup resistors will have done their thing long before the CPU starts executing the instructions in the EPROM. When you turn on the ignition switch, there is a chip in the ECM that holds the CPU in reset until the power is stable.  The switch/pullup resistors will have done their thing long before the CPU starts executing the instructions in the EPROM.

]]> By: Tom http://www.iroczone.com/2009/10/understanding-how-the-code-switching-eprom-circuit-works/comment-page-1/#comment-231 Tom Tue, 15 Feb 2011 22:53:51 +0000 http://www.iroczone.com/?p=71#comment-231 <!--[if gte mso 9]>--> Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 <!--[if gte mso 9]>--> <!--[if gte mso 10]>--> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} I really like this idea.<span>  Have you tried it yet?</span> I am not sure about your notting circuit.<span>  </span>I wonder what would happen on startup.<span>  </span>If it talks longer for the dip switches to be notted than it does for the computer to read the memory location you could get a strange error.<span>  </span>Granted, the inverter would almost certainly start up faster than the EPROM.<span>  </span>I think a simpler solution would be to use a STDP switch.<span>  </span>The second pole could be used as a normally closed dipswitch.<span>  </span>They are available at mouser.com.<span>  </span>

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I really like this idea.  Have you tried it yet?
I am not sure about your notting circuit.  I wonder what would happen on startup.  If it talks longer for the dip switches to be notted than it does for the computer to read the memory location you could get a strange error.  Granted, the inverter would almost certainly start up faster than the EPROM.  I think a simpler solution would be to use a STDP switch.  The second pole could be used as a normally closed dipswitch.  They are available at mouser.com. 

]]> By: ron http://www.iroczone.com/2009/10/understanding-how-the-code-switching-eprom-circuit-works/comment-page-1/#comment-207 ron Thu, 25 Nov 2010 17:34:12 +0000 http://www.iroczone.com/?p=71#comment-207 I WANT A CHIP TO HANDLE 450 TO500 HP I WANT A CHIP TO HANDLE 450 TO500 HP

]]> By: Tom http://www.iroczone.com/2009/10/understanding-how-the-code-switching-eprom-circuit-works/comment-page-1/#comment-121 Tom Wed, 31 Mar 2010 06:04:52 +0000 http://www.iroczone.com/?p=71#comment-121 Hello, awesome work.  I am designing a similar circuit for using a 2M chip where a 512K chip was, and switching between programs.  Have you considered grounding the switches to vehicle chassis ground?  Is that a bad thing?  If that is fine then it would mean one less wire into the PCM, as you dont have to run the ground wire all the way back.  Then I would just have a switch for each A16 and A17 to have up to four programs.  Also, I suppose this could be a logic thing, but in the circuit when you ground any of the three switches the easiest path to ground for the 5V will be to GND, so would you still have a logic high on the other two, or would this ground out all of the 5V to anything?  In a regular circuit I would switch between 5V and ground with a SPDT switch directly in-line. Thanks. Hello, awesome work.  I am designing a similar circuit for using a 2M chip where a 512K chip was, and switching between programs.  Have you considered grounding the switches to vehicle chassis ground?  Is that a bad thing?  If that is fine then it would mean one less wire into the PCM, as you dont have to run the ground wire all the way back.  Then I would just have a switch for each A16 and A17 to have up to four programs. 
Also, I suppose this could be a logic thing, but in the circuit when you ground any of the three switches the easiest path to ground for the 5V will be to GND, so would you still have a logic high on the other two, or would this ground out all of the 5V to anything?  In a regular circuit I would switch between 5V and ground with a SPDT switch directly in-line.
Thanks.

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