24k #22 — IO-lanthe
A recent Times article on the end of hereditary peers in the UK House of Lords reminded me of the terrific W. S. Gilbert line “The House of Peers, throughout the war, did nothing in particular, and did it very well” from the G&S operetta Iolanthe.
Faint praise, perhaps, but it describes perfectly the job of a very-low-power microcontroller. Many early microprocessors didn’t have a halt instruction. They didn’t know how to stop by themselves. In contrast, the job of an ultra-low-power controller is to be stopped except when absolutely necessary. TI’s MSP430 line genuinely excels at doing nothing in particular and doing it very well. A true compliment. MSP430 is our 22nd entry in the 24 x 24k for 2024 series.
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In the thirty-odd years that TI has been selling these things, there have been tens of thousands of designs built around them. Digikey has about a thousand variants of the MSP430 in stock today. This is a 24k series, though, so let me narrow it further. Digikey has 11 MSP430 variants with 24k flash in stock today with a range of RAM sizes, peripherals, packages, and speeds. While these parts may excel at doing nothing in particular, the range of what they can do when woken is matched by few other microcontroller families.
The average MSP430 part has a part number with almost as many letters as an Intel 4004 had pins, but where does the MSP part come from? The 430? Did the whole thing just show up fully formed in 1992 with no ancestor? What does a TI part number mean? Does MSP430 give us any clues about whether an ancestor lurks in TI’s back catalog? That’s a bigger topic than I want to handle today, but I did find an intriguing note that TI intended for the MSP430 to be able to replace an earlier 4-bit programmable signal processor. Perhaps that ancestor traces its roots to TI’s original microprocessors. Does the 16-bit MSP430 have anything in common with TI’s earlier TMS-990 16-bit architecture? Are there hints in the processor embedded in the TMS-9900 core adapted to the TMS-380 processor for token ring? That architecture included a register cache for the 990’s memory mapped registers?
I think they look completely unrelated, but that does’t mean the msp430 has no ancestor. I leave it to you, dear readers, to find it and share it with me.
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