BBC Microcomputer - How Many?

Total production of all varaints of the BBC Microcomputer is usually quoted as 1.5 million. The total on this page is based on analysis of serial numbers gathered from various sources, including the StarDot forums, personal websites and photos on eBay. I am still collecting data so all estimates on this page could change, however as of 15th March 2023:

Estimated total production of all 8-bit BBC Microcomputer variants is 956,000

This total is based on the serial numbers of 1,844 computers. That’s 0.19% of the estimated total and a 57% margin of error compared with the 1.5 million total.

The difference could be explained in a number of ways. It is possible that whole ranges of serial numbers are not represented in our data (our total for Export-specification machines is far lower than the 50,000 machines Acorn is said to have ordered). Perhaps a large number of machines produced under licence by other manufacturers are not included. For example, the data contains a handful of serial numbers belonging to computers built by SCL in India but Acorn also reputedly licensed production in other countries too. Another possibility is that the 1.5 million total includes the 32-bit ARM-based machines which were also badged as a BBC Microcomputer.

The total can be broken down by variant, to show the relative production numbers of Model A/B, Export, B+/B+ 128K, Master Series and Master Compact.

Represented visually, the proportions of each model are easier to see:

Model A/B Production

Let’s look at Model A/B production in more detail. This excludes the B+/B+ 128K and Master variants. The graph below shows approximate monthly output from each manufacturer, along with the current PCB issue(s) at the time. Models A and B are grouped together because although each model has its own product code — ANA for Model A and ANB for Model B — the product code was not included in the serial number for the first 18 months of production. This makes it difficult to make estimates of how many of each type were produced each month.

Note that there is a significant overlap between the beginning of Issue 7 production (June 1983) and the end of Issue 4 production (May 1984). This is because the Issue 7 board was adopted at different times by each manufacturer and Keltek built Issue 4 machines for some time after the other manufacturers had switched over to Issue 7. Why Keltek would have been using Issue 4 PCBs is unclear; perhaps Issue 4 boards continued to be produced alongside the Issue 7 versions — or perhaps the entire remaining stock of Issue 4 boards was assigned to the company to last for the entire production run.

Production volumes have been estimated by using date labels on PCBs where they are available. Not all manufacturers affixed date stickers so for those, the production is estimated based on volumes reported in contemporary magazine articles.

Model A/B Production By Model

The same PCB is used in both the Model A and Model B. Model B PCBs have more components fitted, whilst the Model A variants have empty sockets or spaces ready to accept the components necessary up upgrade them to Model B specification.

So how was production split between Model A and Model B? The fact that the product code was not included in early serial numbers makes it difficult to be precise. For example, none of ICL’s serial numbers included a product code, but all machines from serial number 005000 had the entire 32K of RAM soldered to the PCB, so we can be certain that they were all Model Bs. ICL machines with lower serial numbers could have been built as Model A or B and there is not enough information available to estimate the proportions. On the other hand, Cleartone is simple: all machines they produced were Model A specification, except for a very small number of Issue 1s — only some of which were Model B.

Acorn expected the Model A to be the more popular of the two and planned production on a 2:1 ratio (Model A:Model B). This projection was quickly proved wrong and the Model B eventually outsold the lower-specified model by a considerable margin.

The eventual Model A:Model B ratio was closer to 1:20. Of the relatively small number of Model As originally manufactured, very few remain in their unmodified state.

Model A/B Production By Issue

The issue number of a Model A/B machine is determined by its main PCB. Five numbered issues were manufactured: 1, 2, 3, 4 and 7. Issues 5 and 6 were drawn up but not put into production. Machines based on Issue 1 boards were not sold to customers.

So how many of each issue were produced?

Each issue was produced in greater quantities than all the issues preceding it combined. This makes the latest issue — Issue 7 — by far the most common.

The Issue 1 sector of the pie chart is so small as to be almost invisible, but if you zoom in on the graph you will see it. 90% of all Model A/B machines are Issue 4 or later. 99% of all Model A/B machines are Issue 3 or later.

Serial Number Ranges

The production figures for each model can be broken down by serial number range. This gives an indication of how many machines were produced by each manufacturer which Acorn subcontracted to build them.

The tables below show the lowest and highest known serial numbers in each range. The count column shows how many examples of serial numbers in that range are known. This is followed by the highest and lowest known serial numbers — your computer might be listed here. The range column shows the difference between those two extremes, giving the minimum possible production. The est. total column shows the estimated total for that range, based on the difference between the lowest possible serial number and the highest known serial number rounded up to the nearest 500 (but see the footnote on AB Electronics serial numbers for details of an exception to this).