The Founders Reward and the Dev Fund are different in some very important respects, to the extent that I think it’s incorrect to say the Dev Fund used to be called the Founders Reward.
The Founders Reward (FR) consisted of 20% of new ZEC issuance over the first four years (i.e. 2.1m ZEC). It was distributed to the Electric Coin Company’s shareholders (the investors who invested $3m in ECC to fund the development and launch of Zcash, the Seven Scientists who invented the cryptography that underpins Zcash, and Least Authority Enterprises) and options holders (including ECC employees and advisors who received options in ECC as part of their compensation package).
Originally, none of the Founders Reward was allocated to fund or support ongoing development. To quote from ECC’s quarterly reports, “in order to fund the continued operation of ECC in 2016, the company agreed with Least Authority Enterprises (LAE) to purchase a portion of LAE’s right to its share of ZEC from the Founders Reward (10/2016 through 11/2020), in return for $250k up front and $3.75M payable in September of 2024”. These coins that ECC received from LAE’s share of the FR were often referred to as the “strategic reserve”.
LAE also donated a portion of its FR coins to the Zcash Foundation.
The Founders Reward was only ever intended to last for four years.
During the time I was at ECC, we conceived an “enterprise strategy”, whereby ECC would sustain itself, pay salaries, etc. by generating revenue from commercial activities. The deal with JP Morgan was the first step along that road but, in the end, the enterprise strategy was abandoned in favour of seeking funding from the blockchain.
I believe that the first public mention of the Dev Fund concept was by @Shawn, in early 2019.
We’ve published a blog post that includes a short history of the Dev Fund.