Clark Foley 7804

Ex-Tektronix engineer Clark Foley built a ``7804 using part from a 7854, 7834, 7603, and a custom front panel.

Regarding this project, Mr. Foley explains:

For your amusement, the 7804.

Many years ago, 1978-ish, toward the end of the 7854 development, I began to acquire bits and pieces of derelict 7854 hardware that I salvaged from scrap piles of discards. I acquired a functional analog portion of the scope that included a plugin bay from a 7834. Without any of the 7854's smarts, I had a functioning 7804N (N for no readout). A prototype of the 067-0912-00 Analog Test Card knitted the analog scope together. It had the 7854 front panel keyboard that teased and challenged me to finish it. I had E-phase and mostly A-phase hardware and a couple of build samples used by the prototype assemblers as references. These build samples were never tested before becoming obsolete but I found that many of them worked. As with many projects, my work on my 7854 kit build got derailed by more interesting and demanding tasks as well as marriage, a child and a very old house in need of repairs. I used the 7804N on occasion but it always bugged me that there was no readout and it had all of the processing buttons on the front panel.

Many years past. It was now 2022 and I had resigned from Maxim Integrated Products and had no other demanding obligations. It was time to do something with my stash of electronics; either recycle or build something. I decided to see what I could do with the 7854 carcass. A close examination of the digital mother board revealed a couple of crunched connectors. That was actually a relief to me as I did not want to try to troubleshoot all of the digital boards that I had acquired and try to integrate A-phase, B-phase and pre-production hardware. It wouldn't work with firmware anyway! I decided on something far easier and yet useful. I decided to assemble a 7804, with the classic stroke-style readout from a 7603 and with a new front panel design. I also replaced the bulbs behind the Vertical and Horizontal Mode select buttons with white LEDs. If you look closely, you will see where I repaired two of the Vertical Mode switches with little wire loops to re-attach them to the board.

In the end, the 7804 is a bit like Johnny Cash's car from the song "One Piece at a Time," although nothing was smuggled.

As with the work of Dr. Frankenstein, it might be considered blasphemous or merely a good use of scraps.

• 

  Tearing into the incomplete 7854 prototype

• 

  7854 with front panel removed and empty card cage. It never had the cards.

• 

  Modified front panel casting to support new panel layout.

• 

  Final fitting of new panel

• 

  7854 motherboard and cage. The first position in the ROM slot has a damaged contact.

• 

  7804 panel close up. Resolution was lost when resampled by the print shop.

• 

  7804. Note the number in the extreme lower left corner of the plug-in bay.