Wednesday, December 3, 2008

Logic Analyzer

I went to my first SHARC meeting in months. Was good to meet some new folks and say hi to the regulars.

FIRST has started up so am thinking about attending their next meeting on Sunday. I've wanted to get involved in this kind of thing so now is a good opportunity.

Aside from a good time, one of the guys gave me a Hewlett Packard (HP) 1650A logic analyzer (see photo). Could be interesting and even useful, who knows. The machine didn't come with probes (they are called "pods") or the operating system disk. I wondered if I could get this thing working.

If you've never resurrected obsolete equipment you should at least try it once. It's a hoot. Technoarcheology. (Remind me to tell you about the computer club we formed in college...)

The pods are available on that famous auction site for generally $30-50 each and the 1650A can take 5 of them. Hm.

I can make the boot disk for free with a little digging (for information) and a spare 720K 3.5" floppy. The machine requires this boot disk to be formatted using LIF (Logical Interchange Format) -- just to make this exercise a little more challenging. Here are the steps to building a boot / disk / operations system disk:

Choose 'DOS to LIF Copy'
Use these settings:
- DOS File Name: (File you want to copy, start with SYSTEM_)
- File format conversion: Binary image: No format change, user-def. type
- All other can stay the same
With the cursor on the File format conversion line, press F6 to set
the file type.
For system files (SYSTEM_ and PVTEST_)
- User-defined LIF file type : C001
- Implementation specific field: 534F544F
For config files
- User-defined LIF file type : C120
- Implementation specific field: 534F544F
For other files (Reverse Assemblers, etc)
- Unknown.
- If you have a disk list it with LIFUTIL. LIFUTIL shows the
type as a signed decimal number. Convert it to hex.

Hope this helps someone out especially in finding all the necessary software. Took me an hour to find a download site for the operating system... I was searching all over when all I had to do was search for 1650A on the Agilent site. Duh! :)

As you can see from the photo above I have the machine booted successfully and was able to load a couple of the demos. You can probably tell that the display is really dim. The setup manual explains that there's an intensity knob on the back. No dice. The service manual explains there is a "sub bright" control inside that can be used to adjust the base intensity setting. I'll try that next. Failing that, some type of electronic repair may be required.

1 comment:

  1. I really needed an logic analyzer.

    I just picked up a 1651a (which is almost the exact same unit) for $90 including the cables/pods system disk. It's a great piece of equipment to have. It lacks some features of some of the other 16xx family members though: Ie: full a-z keyboard and a way of decoding timing waveforms into readable data. Still, it's good for micro work!

    You should be able to get a replacement tube cheap if it really needs it.

    The only real problem I see with these old units is that if the sum of parts needed to get them back together may be greater than a PC-based unit like LOGIC ($150)

    Austin Robot Group


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