Dendera Lights on Tektronix 4052, 4054A and 4051 Emulator

[nikola-wan]

My first exposure to the Dendera "Lights" in Egypt was when I found Tektronix 4014 terminal plot files - on @jdreesen's ftp save of Chuck Forsberg's OMEN website in my post #10 in my first VCF thread in 2018:
tektronix-4051-4052-4052a-4054-4054a-program-archives - Aswan Dendera Lights

Here is the 4014 bitmap image of Dendera Lights - displayed using the excellent Tektronix 4010 vector display emulator:

GitHub - rricharz/Tek4010: Free Tektronix 4010, 4013, 4014 and 4015 terminal emulator for Raspberry Pi, Linux, macOS (Macintosh) and Windows

Free Tektronix 4010, 4013, 4014 and 4015 terminal emulator for Raspberry Pi, Linux, macOS (Macintosh) and Windows - rricharz/Tek4010

github.com

The file is named z_aswan.plt in the pltfiles/More_pltfiles included with the Tek4010 emulator.



The above image was created by Tektronix engineers in the early 1970's using dots with the same brightness but organized in 2x2 cells as shown in this zoom of the screenshot above:




I watched a very interesting video this morning: Dendera Light (Re)Discovered? Ancient Electricity from Egyptian Pyramids that was an interview with William Sosa, a researcher that had been working on replicating the Dendera Light for 30 years. He believes it was a plasma effect with mercury vapor and demonstrates his reproduction in the video and shows on a breadboard how it may have been created.

After watching the video I decided to make a new Dendera Light R12 bitmap image from an article on the web dendera-light-bulb-explained - Fig.4 Picture of actual relief – Photo credit: Mick Palarczyk



Here is the Dendera Light bitmap I created from the photo:

1. Using PhotoDemon to invert the image, adjust the levels, and create a dithered dot black and white BMP file
2. Exported to S19 ASCII text format with HxD
3. Using my Flash Drive bitmap create program on the Tektronix 4051 Emulator to create the 4050R12 format image

Here is that 4050R12 image displayed on the Tektronix 4051 Emulator:



And displayed on my Tektronix 4052 computer:



and displayed on my Tektronix 4054A computer:



I have attached a Dendera lights zip file with the following Tektronix 4050 BASIC Flash Drive files:

• 1 - simple bitmap viewer for Aswan Light2 R12 BMP file 5
• 3 - my DitheredBW create program using two Flash Drives in the 4051 Emulator (read from @5:4, write to @6:5)
• 4 - Aswan Light2 S19 ASCII DATA input file
• 5 - Aswan Light2 R12 BMP BINARY DATA output file
• 124 - LAST file (always required in every Flash Drive directory)

 

[nikola-wan]

I just posted a new Dendera directory in my Tektronix 4050 program repository on github: Dendera Light

As I was rewriting the README in this github directory - I discovered that the Tektronix 4010 plot had two brightness levels for each dot in the 2x2 cell which could provide eight levels of brightness for the 2x2 cell.

I have not found the 4054 BRIGHTNESS command in 4050 BASIC to offer much variation in brightness - possibly due to my miscalibration of the 4054A brightness adjustments.

This is why I created my black and white (actually green) dithered dot R12 bitmap image - which also runs on all 4050 computers including the 4051 Emulator.

 

[stepleton]

I have not found the 4054 BRIGHTNESS command in 4050 BASIC to offer much variation in brightness - possibly due to my miscalibration of the 4054A brightness adjustments.

Same here, although nobody would call the display in the 4054A here pristine.

 

[nikola-wan]

Same here, although nobody would call the display in the 4054A here pristine.

How long do you wait after turning on the 4054A with color storage CRT before using it?

I wait about 15 minutes - and if the 4054A has not been used for days - I may see some green spots in the corners or edges, but they disappear after continued use including PAGE commands.

If I turn the 4054A off and later that day turn it back on - the screen may be usable in ten minutes without any spots.

 

[nikola-wan]

Looking at the zoomed view of the aswan.plt Tektronix 4010 or 4014 file in my first post, I now think they were using a 3x3 cell, not a 2x2, since I see dim spots in what I thought were the blank dots between '2x2' cells - in particular below the arm of the figure on the far right side of the image. This would increase the number of different effective brightness levels of each cell.

Also - I looked at a Google map of Dendera - Hathor's Temple, where the Dendera Lights are in a crypt below the temple, and it is almost 300km from the temple. I don't know why Tektronix engineers would have labeled their image aswan.plt, unless the photo they used to create their plot file was mislabeled.

 

[stepleton]

How long do you wait after turning on the 4054A with color storage CRT before using it?

I give it half an hour if I'm intending to take photos or do anything where quality matters.

 

[nikola-wan]

I did find a Tektronix tape I received from the Jack Everson estate labeled "4014-4015 Point Plot Flying Spot Scanner" also marked on the label "RETURN TO JACK EVERSON", that I will try to recover later.

I have attached a Tektronix Storage Tube Terminals pdf file I made from archive.org's capture of Chuck Forsberg's (Tektronix program manager for 401x terminal development) OMEN website that described the Flying Spot Scanner and 2splot program (part of vplot package) which could use dithering instead of greenscale if special point plot is not available.



It looks like the Racquel Welch plot was done in dithering mode.

I brightened that Racquel image for better viewing - still not very clear:



I had dehydrated for 48 hours at 134F four other tapes from Jack's estate yesterday including the Option 30 Games tape, but none of them could be recovered Possibly the donor tape belt from a DC600A cartridge had been stretched too much as I had used it several times in the past to recover other tapes.