I'm just hoping I can spot some ugly, worn, misidentified example on eBay or somewhere else before anyone else does. I'd be perfectly content to own the "worst known" example of 45/1 so long as that incuse legend was clear.
The As was a measure of weight and was broken into 12 parts (VNCIA or ounces). I think it was a weight before it was a coin. Wealth was measured in Asses as early as Servius Tullius, the 6th king of Rome. He reigned from 575 to 535 BC. He divided Roman citizens into Classes by wealth, see the table below from The Beginnings of Rome by T J Cornell. One As equaled a Roman pound = 327 grams. It is likely that cast bronze was used for money before coins introduced in 280 BC. The earliest cast bronze coins were based on an As of about 330 grams.
Thank you @red_spork and @rrdenarius that provides good context for appreciating the coins a bit more. Looking at that Servian Reform chart it seems remarkable to me that 11,000 (or less?) asses of capital (3.597 metric tons!) constituted the least wealthy class. With Tin at 18.83 USD/kg and Copper at 5.81/kg today 11,000 asses of 10% tin bronze would be worth 6,773.15+18,808.71=25,581.86 USD, or if it was 11,000 asses of pure copper as the chart suggests then that would be 20,898.57 USD, either figure representing a lot more financial capital than the least wealthy classes of today have on hand. Clearly one can't draw linear economic comparisons across 100, let alone 2,500 years but it's interesting nonetheless. From the modern collector perspective it seems as though the Denarius is viewed as the base unit, like a 1$ or € or £, but at that time it appears as though it was viewed as a 10$ or € or £ denomination. Pedestrian observation to be sure but I appreciate having the gears turn thanks to quality threads like this. Sorry for getting off-topic.