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标题: 74LS21 fails with TL866 [打印本页]

作者: gmc 时间: 2022-3-22 21:05 标题: 74LS21 fails with TL866

Testing a known good 74LS21 fails with TL866II-Plus App Ver 11.90

作者: yovish 时间: 2022-3-24 06:07

回复 1# gmc

Please post a screenshot showing the erroneous test.

作者: yovish 时间: 2022-3-24 21:41

I can already see the screenshot, it hasn't displayed for a while,

Yes this logic vector is wrong, because pins 3 and 11 are unused/not connected (NC), so instead of expecting the value "H" (TTL logic level high/logic value "1"), there should be an "X" there as shown. In some time this vector should be corrected. Thank you for the information.

Please have the administrator move the topic to this directory:
http://forums.xgecu.com/forumdisplay.php?fid=17

图片附件: 7421 - Bad Logic Vector.png (2022-3-24 21:40, 124.56 KB) / 下载次数 10594
http://forums.xgecu.com/attachment.php?aid=1183&k=a3909dfe0ece3f9253e57d07b38d5c71&t=1732558866&sid=w79fOL

图片附件: 7421 - Corrected Logic Vector.jpg (2022-3-24 21:40, 197.9 KB) / 下载次数 10671
http://forums.xgecu.com/attachment.php?aid=1184&k=13e049d8487794d085a3c0d1c6596382&t=1732558866&sid=w79fOL

附件: 7421 - Corrected Logic Vector.lgc (2022-3-24 21:41, 2.15 KB) / 下载次数 28202
http://forums.xgecu.com/attachment.php?aid=1185&k=c50ab1cf152e344059968f94910fabc0&t=1732558866&sid=w79fOL

作者: yovish 时间: 2022-3-26 00:01

回复 1# gmc

Out of curiosity I checked what the logic vector of the 7421 chip looks like from other companies. I found a couple of companies that also have the wrong vector, but I guess they don't have as much support as XGecu, which will have a revised logic test any day now.

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