List of Remaining Kenbak-1 Computers:
Listing all Remaining Original Kenbak-1's:
By best estimates, about 51 original machines were made including the prototype and the machines sold by CTI Educational Products. For explanation of this estimate, see our FAQ page. Currently, 14 computers are known to exist, but there are rumors of a few more.
Purpose and Naming Conventions:
This list aims to do 5 things:
List all computers believed to still exist and track their provenance.
Archive description and photos to help identify each computer and differentiate it from others (photo archive is currently restricted, as many photos have copyright issues.)
List location/owner (or approximate location if anonymous owner.)
Establish name(s) or "nicknames" to facilitate clear communication.
Note any "non-verified rumors" of a new or lost computer.
For names (nicknames) we select the person who owned and preserved the computer through the 80's when it was most likely to be discarded, rather than current owner. Hence, computers from Robert Nielsen's technical school are named "NielsenX". Similarly, Erik Klein's computer is named "Crosley" but since everyone already knows this as "Erik's Kenbak-1" multiple nicknames are appropriate. If an original owner is unknown, the serial number or another unique feature may be reasonable.
Red dots show the location
of known original Kenbak-1's
The List of Remaining Original Kenbak-1 Computers:
1) Prototype (John1):
Provenance: John Blankenbaker kept this until 2015 when he sold it by Bonham's Auctioneers in 2015. for $31,250. It was purchased by a California retailer of scientific and technical artifacts who listed it for $65,000 in their catalogue, then sold it to Achim Baqué of Germany (in the Cologne Bonn Region) for $41,250. More details on provenance are <HERE>.
This first prototype was very different from "production" machines. Printed circuit board is labeled "Kenbak 10000 Rev " (without the "A" or "B") and many jumpers/corrections on the PC board. Power supply and front panel graphics are different, and no "lock" switch. The store button is a red "enter" button. Since this photo, Achim had ]Blankenbaker autograph the top. Many pictures, and a story is at his "thefirstpc.com" web site. (Photo courtesy Achim Baqué of Western Germany.)
2) Serial #216 (John 2)
Provenance: Kept by John Blankenbaker until 1986, when he donated it to "The Computer Museum" in Boston". In 2000, when they closed, it was transferred to the Computer History Museum in Mountain View, CA. While serial number suggests it was the last machine made, it is actually one of the first, with a "Rev A" circuit board. More details on provenance are <HERE>.
Recently replaced aluminum handles (2/23), It's been on public display now for almost 40 years. A link to the display is HERE.
3) Serial#183 (John 3)
Provenance: Assembled circa 1972, it didn't work until 5/2010 when John fixed it and sold it on eBay. It was purchased for $25,600 by a collector in Monzo, Italy, who resold it via eBay in February 2016 for $35,000. It's now owned by a collector in Massachusetts shown online at www.oldcomputermuseum.com More details <HERE>.
Great condition. All lights were replaced with a modern substitute, one aluminum handle was replaced. There are some modifications to the memory clock driver circuits, as Blankenbaker thought he found an error. Read more about that bug and fix <HERE>
4) Crosley (Serial #197)
Provenance: Tom Crosley, an engineer/computer scientist purchased this new in 1971 directly from the Scientific American ad, and used it extensively while in grad school. He even added a teletype input interface. In 2004, he sold this on eBay and Eric won it for $2000. Erik posted extensive information on his "www.vintage-computer.com" website. Click <HERE> for more provenance history.
This was the first Kenbak-1 documented on the internet with high-resolution photos of the internals. This computer has an unusual modification, where a chip was placed in IC99 location (normally empty) with jumpers into the circuit. Tom Crosley explained that it was for an ASR-33 teletype interface he made, to help enter programs. John Blankenbaker's autograph is inside the top cover.
Provenance: One of 8 computers preserved by Robert Nielsen, owner of Nielsen Electronics Institute. He traded this to Herbert Eisengruber of the "Nova Scotia Computer Museum" in Canada for a used laptop in April, 2003. This was sold when the Museum closed, to a collector in Middleton, Nova Scotia, who sold it on eBay around 2019. It was acquired March 2023 by the Computer Museum of America, as their first Kenbak-1 owned by the museum, not loaned by the founder. Not clear if this is on public display yet. More details on provenance <HERE>.
Electrolytic caps were all replaced, and a muffin fan was mounted on back, outside the case. Most photos show it missing handles, but it has handles. Branded CTI. This is the first sold by Nielsen (and Eisengruber) so it possibly was the least coveted due to modifications. Photos are <HERE> at the old Nova Scotia Museum pages. (Photo courtesy Herbert Eisengruber.)
Provenance: This is the second of the 8 computers preserved by Robert Nielsen, who wrote about how the old switches were replaced with these momentary toggle switches. This was part of a lot of 6 computers sold to the Nova Scotia Museum soon after they got his first. When the museum closed, Herbert sold this to Lonnie Mimms, founder of the Computer Museum of America in Roswell, long before the museum opened. This likely remains in storage, and has not been on public display. More details on provenance <HERE>.
The blue modified buttons are the main distinguishing feature. Nielsen wrote how the buttons were replaced in hopes of improved durability. It has holes on top like all the Nielsen machines. (Photo courtesy Herbert Eisengruber)
7) Nielsen3 (Grey Case)
Provenance: The 3rd of the 8 computers preserved by Robert Nielsen, then sold as a lot of 6 to the Nova Scotia Computer Museum. When that museum closed, Herbert Eisengruber sold this to the current owner in 2009. More details on provenance <HERE>.
This is a very interesting computer, even without the grey case bottom, or the CTI serial number sticker. This was the first noted "Revision A" circuit board, an intermediate between the prototype and production models. Possibly the second Kenbak-1 John made, right after the prototype. Read more about this unusual machine <HERE>.
8) Nielsen4 (Serial #185)
Provenance: This is the 4rd of the 8 computers preserved by Robert Nielsen, then sold as a lot of 6 to the Nova Scotia Computer Museum. When that museum closed, it was sold to Vinal Applebee, who was planning the "Maine Computer Museum" which never materialized. It was auctioned by Germany-based "Auction Team Breker" on November 7th, 2015 for 41808.78 Euros including fees (about $46,000 at the time) to the Munich museum. (Deutsches Museum, Munich). This might be the computer in the mysterious old photo with the black interface box on top. More details on provenance are <HERE>.
Identifiable by some distinct scratches in the top of the case and a dent in back near fan (dent suffered after Nova Scotia, before Breker). (Photo courtesy Maksym Kozlenko, Creative Commons Link here.)
Provenance: This is the 5th of the 8 computers preserved by Robert Nielsen, then sold as a lot of 6 for to the Nova Scotia Computer Museum. When that Museum closed, Herbert sold it around 2008 to an unknown buyer. This is the only computer in this list without a known recent owner or location. More details on provenance <HERE>.
Herbert said that a couple buyers wanted to remain anonymous. Persistent hounding has not revealed more. (Photo courtesy Herbert Eisengruber)
10) Nielsen6 (Serial#194)
Provenance: This is the 6th of the 8 computers preserved by Robert Nielsen, then sold as a lot of 6 to the Nova Scotia Computer Museum. When that Museum closed, Herbert sold it around 2008 to an unknown buyer, and eventually was bought by Lonnie Mimms, founder of the Computer Museum of America, in Roswell, Georgia. More details on provenance are <HERE>.
When this was acquired from Nielsen, this had a foil "CTI" label over the Kenbak-1 logo, but that was removed by Eisengruber. It's on loan to the museum by it's founder. (Photo permission courtesy CMoA)
11) Nielsen7 (Big Holes)
Provenance: This is the 7th of the 8 computers preserved by Robert Nielsen, and the last of the 6 sold to the Nova Scotia Computer Museum. When that Museum closed, Herbert sold it around 2008 to Wigton Museum/Timeline Computer Archive, which has a world-class collection, but is still fundraising for a permanent display location. Currently, most of its artifacts are in storage, with occasional pop-up displays. More details on provenance are <HERE>.
No rear labels or serial number, it's the only specimen that had very large holes in the top cover, which helps in identification. Great YouTube video <HERE> and the museum's Facebook page is <HERE> (photo permission courtesy Mike Armstrong, Wigton Museum)
12) Nielsen8 (Serial #203)
Provenance: This is the 8th of the 8 computers preserved by Robert Nielsen, and the last he sold, after selling the first 7 to the Nova Scotia Computer Museum. After failed eBay auction, this sold in May 2011, for $20,000, along with other memorabilia, to Lonnie Mimms, founder of the Computer Museum of America. More details on provenance are <HERE>.
This YouTube video has Robert Nielsen showing the inside and running it. This seems to remain in storage and has never been on public display. (Photo courtesy Robert Nielsen.)
13) Serial #212 (Seattle)
Provenance: Based on blemish on top of case, the hex screws, and the "hanging" angle of the read and start buttons, this is the computer which sold on eBay August 1, 2005 for $10,850, from AuburnAlabam to CollectRHC. With the closing of the LCM, this machine may be in limbo for years while Paul Allen's $20BN estate is liquidated.
One blemish to left front cover paint, replacement "hex screws" in front panel. Else excellent condition.
14) Missing Light
Provenance: Unknown. The earliest photo of this machine was April 10, 2014 Facebook photo. In 2016, this computer was shown at a "Pop-Up" display at the Vintage Computer Festival (VCF Southwest 4.0) where they had a surreal "Red Shrine Exhibit" of the Kenbak-1. Possibly only used in traveling or "Pop-up" displays since only the number 10 machine (Neilsen6) seems to be on permanent public display.
For more pictures of the surreal "Red-Shrine" display, and close ups showing why it's clear this is clearly a different machine than other listed machines, click <HERE> (photo permission courtesy CMoA)
Possible Other Unlisted Machines:
There has long been a rumor that an anonymous collector in Tennessee has a Kenbak-1, but details are unknown. This rumor goes back to at least April 2006, predating the sales of the Nielsen/Eisengruber computers, so unless it was sold on eBay in 2005 (Serial #212) or given to the Computer Museum of America in Roswell (CMOA2) it very well could be a true 15th known original Kenbak-1 computer. But this remains unverified.
There is a rumor that two Kenbak-1's have been found in Canada, in the possession of an owner who has had them for years, but supposedly the family doesn't want details public yet. Again, unverified, and somewhat dubious.
Prices of Original Kenbak-1 Computers:
Collectors love to talk about prices, just not prices they paid. That makes this information sensitive for some. All of the following auction information has been publicly available on the internet. And any private sale amount is only included here if several sources repeated it, proving it's not a secret.
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