John, Original 40 pin IDE is not an impedance controlled cable, so I don't think that you will find a characteristic impedance specification for it. However, the Ultra ATA cables (80 conductor, 40 pin connector) are impedance controlled to, I believe, around 75 ohms. They use a GSG configuration and a ground bar in the connector in order to achieve the desired impedance. James R. Jones Dell -----Original Message----- From: John@xxxxxxxxxxxx [mailto:John@xxxxxxxxxxxx] Sent: Saturday, September 14, 2002 12:45 AM To: 'SI-List' Cc: John Lin (???) Subject: [SI-LIST] AC/DC impedance spec for floppy and 40Pin-IDE cables. Dear all SI gurus, Are there any AC/DC impedance spec for floppy cable and 40pin-IDE cable? ATAPI-6 spec. doesn't mention ac impedance for 40pin-IDE but 80pin-IDE cable. Can somebody tell the reason? Regards, John Lin Quanta Computer Inc.,Taiwan, R.O.C. Email: John@xxxxxxxxxxxx Tel: 886+3+3272345 ext. 5183 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu