The SCELBI Registry

CHM SCELBI 8B

A Virtual Museum of Original SCELBI Computers

13 SCELBI Computers Currently Listed

last updated April, 2017

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

possibly Computer Museum of America?
-
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

The main chassis for this unit is now on display at the Living Computer Museum and Lab in Seattle, WA ?
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.

Nat's system without cards
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

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). 


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



Mystery SCELBI 8H- Computer Museum of America

Mystery SCELBI 8H



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


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.


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.


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




Freeman Museum SCELBI 8H

Private Hands


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

Curtis's SCELBI 8H

Curtis's SCELBI 8H
image curtesy of Curtis of Kentucky

Unknown Whereabouts


Mind Museum SCELBI 8H


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