pmem - nesbox/TIC-80 GitHub Wiki

pmem(index) -> val32 Retrieve value from persistent memory

pmem(index, val32) -> prior_val32 Save new value to persistent memory, retrieve prior value.

Parameters

• index : an index (0..255) into the persistent memory of a cartridge.
• val32 : the 32-bit integer value you want to store. Omit this parameter to read vs write.

Returns

• val32 : the current/prior value saved to the specified memory slot.

Description

The name "pmem" means persistent memory. This function allows you to save and retrieve data in one of the 256 individual 32-bit slots available in the cartridge's persistent memory. This is useful for saving high-scores, level advancement or achievements. Data is stored as unsigned 32-bit integer (i.e. in the range 0 to 4294967295, default is 0).

When writing a new value, the previous value is returned.

Memory Persistence

• pmem depends on the cartridge hash (md5) and therefore existing data will be erased if the script is changed.
• Specifiying saveid: with a personalized string in the header metadata will override the default MD5 calculation. This allows the user to update a script without losing saved data.

Example

Use pmem to save how many times the cart has been started.

--pmem demo
--load saved value at slot zero and save it back
--incremented by 1
pmem(0,pmem(0)+1)

function TIC()
 cls()
 print("Started "..pmem(0).." times");
end