Found one of Steve's emails from 2016. Here is an excerpt.Its really a credit to the tiny company that produced these things that so many survive in good order after so many years! Congrats on getting another one running. As to the numbers, Steve Kennedy said they produced 300 Composers all numbered in order from 12,001 through 12,300. Mine is 12,116, and Steve confirmed that meant it was number 116 produced. Mine has the earlier chips from National semiconductor, which had the flaw requiring the workaround. Assuming its in good order you should not have any issues with that, and I have a really hard time telling the difference between mine and the later chips. The earlier ones like mine seem to 'work' more than the later ones, but its very subtle. I have always loved mine and have always been more than satisfied. Given that yours are both in the first half of the 300, I believe yours are both National Semiconductors with the workaround, although I have never been 100% clear on where the line was drawn, so take it for what its worth. I think its 50/50 but again, I didn't work for Audionics so I am not able to say for certain. Steve could tell you, probably, although her told me there is a lot of confusion as the company was not good about keeping records. He said there has even been some confusion about how many units were produced, although he said with confidence it is 300.
"The first chips (National Semiconductor) and the last chips (Exar Systems) both required a special interface due to errors National made in creating the original chips. Exar took some National Tate chips apart and put them under the microscope and discovered some of the worst errors then made their own copies of an "improved" chip with the worst of the National problems bypassed. They still weren't as they should have been but they worked better and smoother in what was essentially the same circuit.
We did serialize them individually as they were built (in order). "300" is the working number of Composers that were produced. All of the confusion caused by the chip upgrades and lack of surviving production records have resulted in confusion regarding the number of Composers that were made."