The SCELBI Registry

A Virtual Museum of Original SCELBI Computers

13 SCELBI Computers Currently Listed

last updated September, 2014

If you have more information send me email

click here to go to Mike's SCELBI web pages

Introduction

The SCELBI (SCientic-ELectronics-BIology) was arguably the first commercially available micro-computer marketed toward hobbyist. SCELBI computer's were built in two types. First came the 8H (h for hobby) and then the 8B(b for business). The only significant difference is the amount of memory that each system could support. The 8H supported up to 4K of memory and the 8B, up to 16K. Except for an extra card, used to extend memory addressing and the memory cards themselves, the two systems shared the same hardware design. SCELBI Computer Consulting sold built up systems, kits and bare printed circuit boards. The number of systems sold number somewhere around 200, with probably 1/2 being completely built up systems and the others some combination of PCB sets and kits. The systems as you will see, vary quite a bit in construction and modifications. At least 1 that we know about has a video card installed!

Serial Numbers

A couple of the original SCELBIs are found with address labels attached to the chassis. These labels have a serial number hand written in ink on them. At least one SCELBI has two such labels with different numbers. As far as we know, systems that were built from PCBs or kits would not have these labels.

If you have an original SCELBI and want to contribute to this effort, drop me an email. Once I feel that your unit is likely to be authentic, and not a duplicate, it will be categorized into the batch that I believe that it would have come from and added to this registry. Upon request, I will withhold your name and personal information. I hope that we will find more systems that can be listed. The number of known SCELBI systems is currently very small.

There is a small possibility that units could be listed twice in this list, especially those units without distinctive enclosures or quality images of the motherboard. I do my best to filter through available information in order to prevent this.

Warning

As time goes on, reproductions are getting harder and harder to tell from originals. Some builders of reproduction systems may go to the effort to find components with the same manufacturer and date code as were used on original systems. When these components could not be found, chips could be relabeled to reflect date code correct parts. At this point, as far as we know, no hobbyist have done this to deceive potential purchasers, but the potential is there. There is also growing potential for people who have inherited a reproduction to accidentally misrepresent a reproduction as an original.

It is hoped that this list will be helpful in authenticating original units. Do to the increasing quality of reproductions, be aware that even the maintainers of this list could potentially be confused by a fake, which might end up on this list. If you are in the market for an original SCELBI, be extremely careful about what you are investing in.

Components

Factory SCELBI's were built to order over a period of several years and others were built from kits or from bare PCBs. Components could have come from any number of sources over this time, so as long as the date code of the component looks relatively in line when the systems were used, almost any compatible component could have been used.

How Many SCELBI's Exist?

It is hard to say for sure. The low number of known units and the extremely slow rate of discovery of new ones isn't encouraging. Based on current information, I'd guess that the total number of existing SCELBI computers is almost certainly less than 40, and possibly less than 20.

Summary of Known SCELBI Computers

#	OWNER/NAME	VERSION	ID	LOCATION	Last Operation	Extras
1	Nat Wadsworth	8B	-	Computer Museum of America	-	Integrated power supply, TTY, and cassette interface into main chassis
2	Robert Findley	8B with Z80	-	Computer Museum of America	?	Hand wired Z80 CPU board added by Bob in the 80s
3	Steve Ciarcia	8H-B	-	Computer Museum of America	?	Ciarcia custom built power supply and boot prom. Also contains 1 1K memory card and 1 4K memory card with only 2K of memory populated
4	Olsen	8H	01-0032	Computer Museum of America	?	Best documented system
5	Mystery	8H	4100-0581?	Computer Museum of America	?	Interesting add in boards
6	Bug Book Computer Museum	8B		Bug Book Computer Museum	-	Digital group video card - only known SCELBI with integrated video.
7	CHM - 8B	8B	3100-0028, 4100-0033	Computer History Museum		Blue bezel - currently on display
8	CHM - 8H	8H	3100-009, 4100-0026	Computer History Museum	?	Very complete 8H system with keyboard, only known keyboard interface #2105-0005, cassette tape, only known oscilloscope interface #2100 + 2101-0004
9	Jack	8H		Munich, Germany (Deutsches Museum?)	2013?	Sold for $15,000 at Brecker auction in 2013
10	Freeman Museum	8H		?	?	Only known original speed loader box - probably has a cassette interface
11	Mark Arnold	8B		USA	2012? - bad memory	Used to develop SCELBAL - one of two known factory power supplies
12	Mind Museum	8H		?	?	No information other than web page
13	Curtis	8H		Kentucky	2011	Apparently built from bare boards - only hand wired backplane

The following SCELBI descriptions are divided into 3 main sections - units seen in old, period photos, units in museums and units owned by individuals. Where possible, the history of unit and interesting characteristics of the board are included in the descriptions. In some cases, upon request, the name of the owner is witheheld.

Here are some image of SCELBI's from 1970's era flyers and advertisments

Here is the image of the 8H as depicted on the first SCELBI Computer Consulting flyer
1st flyer

Here is a crop of an ad from Sept., 1975, Byte Magazine
Byte Sept 1975

SCELBI's In Museums

Nat Wadsworth's SCELBI- Computer Museum of America
First prototype CPU

Handwired prototype SCELBI cpu card. It was made on two standard vector plug boards riveted together.

This is from the collection of Nat Wadsworth (co-founder of SCELBI Computer Consulting)
This collection was obtained from his widow by a collector, who later sold it to the Computer Museum of America
Collection includes his hand wired prototype CPU card
This 8B system with cassette interface and TTY interface cards integrated within the main chassis - this is unusual custom feature of this chassis
This 8B system includes linear power supplies integrated within the main chassis as can be seen below - standard factory supplies came in separate enclosures

The cards are pulled in this view, but you can see the three extra slots Nat added for the cassette interface cards and tty card. Nat also added the power supplies right onto the chassis. The 5 volt supply on top and the -9 supply is mounted underneath the chassis. The I/O connectors on the back are amphenal 78S12 type connectors. Top row is input (6 of them ) and bottom row (8 of them) are output. Each input port supports 8 TTL level inputs. Each output port supports 8 TTL level outputs plus a strobe. The top right amphenal connecter is for power. Most SCELBIs had a 78CP4 in that location which was used to input power to the chassis. With the power supplies embedded in this chassis, I believe that this connector was changed to a 86CP4 to use for power distribution to external devices. The built in I/O capabilities of the SCELBI sets it miles ahead other period machines.

Robert Findley's SCELBI- Computer Museum of America
Bob Findley's Z80 CPU

Image of Robert Findley's Z80 CPU card for the SCELBI

This SCELBI 8B was modified by Robert Finley in the 1980's to run a Z80 CPU instead of the 8008
This SCELBI 8B was part of a small collection obtained by a collector directly from Bob in around 2013, then sold to the Computer Museum of America

Steve Ciarcia's SCELBI 8H-B
Steve Ciarcia's 8H

Like many SCELBI's , the back view of this machine is most interesting. It features a home brew power supply including custom regulator (not pictured).

Steve Ciarcia was well know for authoring the Circuit Cellar colum for many years.
Steve bought the boards directly from SCELBI after visiting their offices.
The story of this machine can be found in the pages of the Mark-8 Users Group Newsletter
1 1K memory card plus a 4K memory card with 2K memory populated making this a hybrid 8H-B
It also boasts a PROM connected to one of the vacant banks on the 4K memory card. It apparently can be switched on or off.

Olsen's SCELBI 8H- Computer Museum of America
Olsen's SCELBI CPU card

Production CPU Card from Olsen's SCELBI 8H

Very well documented at http://www.olson-ndt.com/Scelbi/

Mystery SCELBI 8H- Computer Museum of America

I'm lacking information on this one, but it looks like it has some pretty interesting add on cards

8H - Computer History Museum (Mountain View, CA)
Computer History Museum - SCELBI 8H system

SCELBI (right) connected to keyboard interface (bottom), cassette tape interface (middle left) and oscilloscope interface (top). There is no front panel on this system.
image courtesy of Jack Rubin

This is the most complete factory 8H system known to exist
It is not on display
Including the only known oscilloscope interface
Cassette tape interface
Only known keyboard interface
Power supply isn't in this image, but the CHM does possess one of two factory power supplies known to exist. I'm not sure if the power supply goes with their 8H or 8B, as SCELBI shipped the same power supply with both systems.
This unit came by way of the Boston Computer Museum - An article and picture of it can be seen in the Computer Museum report #14 fall/winter 1985
It was donated to the Museum by Carlton B. Hensley

8B - Computer History Museum (Mountain View, CA)

Computer History Museum SCELBI 8B

A standard configuration SCELBI 8B. The blue SCELBI front panels were anodized aluminum, the legend was screen printed. There were plans formulated for a complete enclosure, but I don't believe any were ever made. That is why there are holes around the perimeter of the front panel.

On display, without accessories or power supply

Jack's SCELBI - Possibly Deutches Museum

Nick's Chassis - wiring

Note the amount wiring required to connect the I/O ports in this factory wired chassis. Very labor intensive. Back in the day, the I/O connectors themselves were cheap - I've seen them listed for $.25 each in period magazines. The decoupling capacitors on the power rails are not standard.

This unit passed through several collectors hands. Jack was the first collector that I'm aware of that owned it
Jack never powered it on, though a later collector apparently found some wall warts and did power it up
Auctioned by Brecker in Germany for around $15,000 in 2013
I believe that this may be now owned by a museum in Munich (perhaps the Deutsches Museum)

Bug Book Museum's SCELBI 8B
Bug Book Museum's SCELBI 8B

Owner added a Digital Group video card making it the only known SCELBI with integrated video
Also some interesting plug in cards, possibly custom made
Based on card spacing, I don't believe that there is a standard backplane with this SCELBI

Private Hands

Mark Arnold's SCELBI 8B
Mark Arnold's 8B

This system was provided to Mark by SCELBI Computer Consulting so he could develop SCELBAL
The system includes one of two known factory power supplies of about 20 that were made - can be seen in upper left corner of image
Cassette interface and TTY interface - stacked behind main chassis
Mark also built a TV Typewriter of his own design.
It is in private hands

Curtis's SCELBI 8H

Curtis's SCELBI 8H

image curtesy of Curtis of Kentucky

Apparently built up from bare boards
Does not include standard chassis kit, so backplane is hand wired
One 1K memory board

Unknown Whereabouts

Freeman Museum SCELBI 8H

Documented on Freeman PC Museum site:http://www.thepcmuseum.net/details.php?RECORD_KEY(museum)=id&id(museum)=22
No longer in Freeman PC Museum's hands
Includes only known original "speed loader" peripheral. This was designed to speed up booting up the system. See SCELBI computer digest - issue #1

Mind Museum SCELBI 8H

Little information available - seen on Mind Museum web page

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