Update 2/10/2020
Supply Precision Updated
The base unit of the ScPrime ecosystem is not the ScPrimecoin (ticker SCP) but instead a unit called a Hastings which has 24 digits or 10^24. It takes a LOT of Hastings to make 1 SCP (0.000000000000000000000001 SCP, a lot of zeroes in the base unit)

As a utility coin powering state channel contracts with the potential for global adoption, there is significant need for extreme coin division. Also, the protocol calculates storage prices using Hastings per Byte per block, creating the need for extremely tiny micro-payments. On 2/7/2020, we changed notional precision such that the base unit is now displayed to the public as 10^27 even though the protocol continues to work in the old precision. The net effect is to move the decimal over 3 places in contracts, wallets and transactions. The purpose is to lower the nominal supply figures for Maximum, Total and Circulating supply, ie it takes 1000x more Hastings to make 1 SCP

The old precision represented supply in the billions while the new display is millions and more inline with the majority of crypto-currency projects. This creates a price comparison more able to trade against BTC and USDT instead of intermediary coins like Litecoin. When the precision changed, the price changed automatically to reflect. Miners, storage users, providers and traders all see values that are 1/1000th of the previous number in wallets and contracts but the value is 1000x of the old values. No dilution occurred or significant change at all as the automatically adjusted price remains constant with previous values.

The long term effect should be to allow for more exchange and information site listings, more interest in the project and ultimately more people using the coins. Because this is only a representation change, no hard fork was necessary and users can always see the old value by downgrading a wallet to a prior version. Exchanges, Mining Pools and the Explorer all show the new representation though.

All of the following have been updated to reflect the new coin precision (see above)

Algorithm: Blake(2b)
Total Supply: Unlimited with declining inflation + coin burn (blog post on Total Supply)
Block Reward: 300 declining by .001 coin per block with a 10 SCP floor
Block Timing: 10 minutes
API Port: 4280
RPC Port: 4281
Hosting Port: 4282

Initial Token Grant
10,551,000 SCP premine for expenses/airdrop as follows

Expenses
51,000 Mining pool maturity cushion: 5 mining pools
200,000 Project/dev expenses
300,000 Nebulous Inc (Sia creator) bounty
1.75m Storage Host Incentive Program
628,000 Exchange listing fees fund

Airdrop
List of positive addresses at Sia block 179,000

3.1m SCP distributed on a 1:5 basis to existing Siacoin holders of record (1SCP for every 5SC).
Over 650,000 wallets received coins with only a handful receiving more than 10,000 SCP as the original supply is extremely centralized in a tiny number of very large and mainly public exchange wallets.

4.5m SCP from exchange addresses stored in a cold wallet.
Coins were not distributed to the top 35 addresses (determined to be exchange addresses), but directed into a cold wallet. 

Project Fee – 20% thru month 6, declining to 10% over 2 years
After block 105,000, the 10% project fee is sent to the collateral burn address to reduce inflation/supply for the duration of the project.

Projected total supply
The SiaPrime supply is built to closely mimic the original Sia supply. The Sia protocol includes two key provisions (storage node collateral, renter allowance) that lock up significant amounts of coins, requiring a large supply. At scale, it is expected that as much as 30% or more of the total supply will be locked in contracts leaving the balance for speculators and future storage budgets. A blog we wrote about this.

Estimates of supply totals by year
2018  13,147,616
2020  38,235,269
2023  55,147,159

ScPrimeFunds
10,000 ScPrimeFunds (SPF) were created and distributed to holders of SiaFunds at Sia block 179,000 as compensation for the open source software development of the underlying protocol. The following spreadsheet includes the breakdown of ownership and transaction IDs – siaprimefunds.csv

At block 59550, there was a hard fork to allow for the creation of an additional 20,000 SPF (initial emission) for the SCP team. Of these, 15000 will be held by SCP, Corp in perpetuity. The remaining 5,000 will be used to encourage support of the project.

There will be another hard fork in November 2020, to remove the original 10,000 airdropped units due to legal questions and issues brought on by the original project.