Ross Milbourne, 09/11/2019

(https://imsaicomputers.blogspot.com/2020/01/imsai-8080-restoration-for-centre-for.html)

(excerpt)

I have a database of machines that have come up for sale in recent years, or are in various collections - both private and in museums. This can be very useful in providing a rough idea of when it was manufactured, along with what some of the major component parts should look like.

The numbering of IMSAI 8080 machines actually started at 001001, with a batch of 25 machines [according to Jonathan Littman 50 seems to be the correct number] delivered in December 1975. This was probably a smart marketing ploy to make it look as though the machine was more successful than it really was to early buyers. In our case, therefore, it was the 2,550th machine off the production line.

From data gathered to-date, this appears to place it just after the middle of the original production of circa 4100 machines made in 1976. Serial numbers from 001002, delivered in December 1975, through to 005104, delivered around the end of 1976, help us to position it very roughly within that year to around mid July.

There are four separate serial number series known to-date:

The first machines ran from 001002 upwards and the last I know of is 005104 (or 00590? where the last digit cannot be seen in the photo). There will be more.

The second series just had a 1 placed at the front, but carried on from where the last series left off. The lowest number I know of today is 1006782 from that series and the highest is 1013228.

It is safe to assume from theferefore that at least 12,227 machines were produced from this, the main series.

The third series is from 1979 onwards, when Fischer-Freitas had taken over the parts and rights. I have only come across one machine in that series, number 25050A.

The fourth series is a bit of a mystery. A machine turned up with the serial number that has a prefix of 'I' and a number of 101110. It can be seen at: http://pc-museum.com/046-imsai8080/

The machine is in Sweden. Could it be that the 'I stood for 'International', and IMSAI created a separate numbering system after opening up that market? It certainly has the last of the types of transformer used, and the capacitors appear to have late 1977 date codes.