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Agilent 1680/1690 Logic Analyzers

Updated: Nov 14

Historically, I have used simple "debuggers" / "analyzers" that leveraged an Arduino Mega, STM32, or Teensy to sample signals and either display debug data or send this data to a Windows application for viewing. While this has worked fine for slower system clock speeds, these solutions are not workable when running higher speeds. (Higher speeds for me means 10 to 20 MHz.)

To step my game up to the next level and learn a bit about more professional tools, I have purchased three Agilent logic analyzers. With a little searching, I was able to purchase Agilent 1680A, 1680AD, and 1690A logic analyzers, including two full sets of cables -- all for approximately $1,000 USD. I upgraded and/or repaired the units, spending less than $100.

1680A Hard Drive Update

The 1680A that I purchased was fully functional. It came with a rotational hard drive installed. I cloned this hard drive to a SATA SSD using IDE-to-USB and SATA-to-USB (Apricorn) adapters -- and Apricorn EZ Gig IV software. (You should be able to most any drive cloning setup.) Using an IDE-to-SATA adapter, I installed the SATA SSD into the 1680A.

1680AD Restoration

I purchased a non-functional 1680AD for a good price. The 1680AD supports a 2 MB full-channel memory depth (four times that of the 1680A). When I opened the chassis, I found there was no hard drive. I installed a SATA SSD using an IDE-to-SATA adapter and restored a factory image to the drive.

Factory Restoration CDs

Agilent has restoration CDs for the different versions of 1680's. These restoration CDs will restore Windows XP (or possibly Windows 2000 for older CDs) along with drivers. User gslick on posted some really helpful information on the hardware models, associated image files, and where to get the image files. See HP/Agilent ftp site? - Page 1 ( In short, I downloaded the entire archive of the old from and extracted the specific images for my version of the 1680AD.

The logic analyzer software can then be installed. It can be downloaded from Logic and Protocol Analyzer Software (32-bit) | Keysight.

1690A Setup

With my pair of 1680's, I had a single set of cables; the 1680AD did not come with any cables. I was hoping to have a second set of cables. These cables are hard to find and/or expensive. I stumbled across an Ebay listing for a 1690A, which is simply the capture frame card portion of the 1680A in a smaller chassis. This unit came with a full set of cables, including an additional signal breakout cable. The unit was essentially sold as untested. When I received it, I found that the unit did not work. After a little troubleshooting, I found that the IEEE 1394 connector on the front of the unit was broken. Rather than fixing the connector, I just connected a firewire cable to an internal connector and ran the cable out the back of the chassis. I tied the cable down internally to provide a strain relief and used a grommet to protect the cable as it exited the chassis. After configuring a PC to use with the 1690A, all is working.

PC Configuration
  • I configured three operating systems to test and learn a bit about this 1690A. First, I loaded Windows XP, then Windows 7, and finally Windows 10. The IEEE 1394 host controller needs to be recognized by Windows. Then, the Agilent logic analyzer software can be installed (see link earlier). For Windows 7 and 10, a legacy IEEE 1394 driver is required; see my note on this later.

  • From what I can tell, the Agilent gear is designed to leverage a Texas Instruments TSB43AB23 IEEE 1394 host controller.

  • I first tried a LinksTek PCIe FireWire card, model PCIE-1394A. I was unable to get this card to work (Windows XP, 7, or 10 -- with either the standard or legacy IEEE 1394 drivers).

  • I had success with an old Gateway E-6610D PC that has an onboard Texas Instruments TSB43AB23 chipset.

  • I also had success with a LinksTek PCIE-TSB43AB23 which uses a Texas Instruments TSB43AB23 chipset.

  • I plan to try other IEEE 1394 cards in the future. I will post updates here.

For Windows 7 and beyond, the Firewire 1394 legacy driver will be required.

  1. Download the legacy driver from Microsoft.

  2. Run the MSI file, which simply extracts the drivers to C:\Program Files (x86)\1394 OHCI Compliant Host Controller (Legacy)\.

  3. In the extracted folder, in a sub-folder for your processor platform (x86 or x64), right-click on the .inf file and choose Install.

  4. From Windows Device Manager, open the properties of the IEEE 1394 Bus Host Controller, choose Update Driver Software, Browse..., Let me pick from a list..., and select "1394 OHCI Compliant Host Controller (Legacy)."

First Use

In the following video, I use my 1690A to look at signals from my 386 DX build. As part of this, I am leveraging debug ports on my 386. These ports use a PCIe x4 slot and a plug-in probing board that includes resistors and capacitors to serve as an isolation network.

Custom Cables

As cables are so expensive, I am experimenting on building my own. More to come on this! I will update this post with additional details as I have them.

Additional Resources

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