1. Save system — PC runtime and file format
   1. PSX memcard emulation
   2. Save file format
   3. Preview block (savemap+0..127)
   4. New game and playtime
   5. Why the load screen looks slow (the progress bar)
   6. Chocobo World
   7. Address table

Save system — PC runtime and file format

How FF8 PC saves work: the memcard-emulation layer, the exact file format with checksum, the load-menu preview block, new-game initialization and Chocobo World transfer. Addresses for FF8_EN.exe, image base 0x400000.

PSX memcard emulation

The PC build keeps the PSX memory-card code and shims file names: internal PSX name BASLUSP008920426NN maps to {GameDir}\SAVE\SLOT1|SLOT2\saveNN (NN = 01..30), and BASLUSP00892C0426 maps to {GameDir}\save\chocorpg. Two emulated “cards” (port 0 = SLOT1, port 16 = SLOT2), 30 saves each. The save/load “memory card” screen is one shared state machine (Save_CardScreen_Update, 0x4E3090) running in load mode (title Continue) or save mode (save points).

Save file format

On disk a save is [u32 compressedSize][LZSS stream] (standard FF8 LZSS), decompressing to a full 8192-byte PSX save block:

File offset	Content
0–383	PSX header: "SC", icon info, SJIS title (playtime “HH:MM” patched in as full-width digits), icon CLUT/frames
384–5411	savemap block — verbatim copy of 5028 bytes from SG_CHECKSUM (0x1CFDC58)
5412–8191	zero padding

• Checksum: CRC-16/CCITT (poly 0x1021, init 0xFFFF, final NOT; table-driven, Save_ComputeChecksumCRC16CCITT 0x500310) over savemap+80..+5023 (4944 bytes), stored at savemap+0 and duplicated at savemap+5024. No other obfuscation or encryption.
• Two-phase commit: the file is first written raw with magic 0xFFFF (and a “write error” SJIS title from the header templates), then the first 512 bytes are rewritten with magic 0x08FF + final title and the whole file is LZSS-recompressed in place (Save_RecompressSaveFileLZSS). A save interrupted between phases is detectable by its 0xFFFF magic.
• Load: requires CRC(buf+80, 4944) to equal both stored copies; then 5028 bytes are copied to SG_CHECKSUM, the RNG is reseeded from save statistics, and engine_restore_game_status (0x495EF0) recomputes derived character/GF stats. No version or region checks beyond the magic.
• The PSX read-back verify states survive in the code but are dead on PC, and a leftover debug quick-loader (Save_DebugLoadSaveFileByPath_UNUSED, 0x4E2DE0) loads a raw file by path expecting magic 0x0FF8 with no CRC check.

Preview block (savemap+0..127)

What the load menu shows, refreshed at save time by Save_BuildSaveFileImage (0x4E2EF0):

Offset	Size	Field
+0	u16	CRC-16 checksum
+2	u16	magic 0x08FF (0xFFFF = interrupted save)
+4	u16	location name ID
+6 / +8	u16	leader current / max HP
+10	u16	save count
+12	u32	gil (Laguna’s gil when the flag says so)
+16	u32	playtime in seconds (display cap 99:59)
+20	u8	leader level
+21	u8×3	party portrait IDs (0xFF = empty)
+24/+36/+48/+60	12 B each	Squall / Rinoa / Angelo / Boko names
+72	u32	current disc
+76	u32	save ordinal (monotonic; the newest save gets the default cursor)

New game and playtime

• New game: Savemap_Clear zeroes the savemap, then Savemap_LoadNewGameDefaults_InitOut (0x56DA10) loads the file init.out directly into savemap+80 — that file is the new-game savemap and can be edited to change starting inventory, stats, flags…
• Playtime: Savemap_TickGameTimeAndCountdown (0x4701B0), called from every module main loop, adds 2191 per frame to an accumulator; every 0x20000 overflow = +1 second (131072/2191 ≈ 59.82 Hz — the NTSC vsync rate, so playtime advances at PSX speed regardless of module frame rate). The script COUNTDOWN uses the same mechanism.

Why the load screen looks slow (the progress bar)

The data is loaded almost instantly — the visible slowness is entirely inherited PSX memory-card theater:

• All I/O is synchronous behind an async façade. Save_EmuMC_ReadFile performs the whole read (including LZSS decompression of the full 8 KB) in one call, then the PSX-style event shim reports completion — so every “async card operation” is already finished by the first poll.
• The card screen is a frame-locked state machine (60 fps menu loop, one state transition per frame). Scanning a slot walks its 30 save files one at a time: issue preview read (state 25) → poll completion (state 27) → card status re-check (state 26) → next file. Even with instant I/O that’s 2–3 frames per file ≈ 1–1.5 s for a slot.
• The progress bar is an animation, not a measurement. It advances at a fixed 64/4096 per frame — a minimum of 64 frames (~1.07 s) to fill — and is merely capped by the scan position ((fileIndex+2)×256). Faster I/O cannot make it faster.
• Leftover PSX pacing shims add structure but little time on PC: the card-test state machine counts down 180 polls (EmuMC_PollCardStatePaced, from the PSX card-detection timing), per-file completion has a 60-frame timeout, and EmuMC_WaitCardEvents180 spins up to 180 iterations — all designed around a real memory card that read 128-byte frames one interrupt at a time.
• Loading the selected save itself (state 74–76: one 5120-byte read + CRC check + memcpy into the savemap) completes in a couple of frames — the multi-second experience is the slot scan plus the bar animation.

A speed-up patch would (a) let the bar cap jump immediately (scan several files per frame — the state machine can safely process multiple files per tick since I/O is synchronous) and (b) raise the bar’s 64/frame fill rate.

Chocobo World

save\chocorpg is [u32 size][LZSS] of 514 bytes: u16 magic 0x08FF + 512 bytes of Pocketstation world data. The savemap keeps a 64-byte mirror (SG_CHOCOBO_WORLD_DATA, savemap+4960) with a once-randomized world ID. Export writes a 128-byte region into chocorpg (converting Boko’s level, clearing collected item counters); import decodes item-class counts into (item, quantity) pairs added to the inventory and merges event/level data back. The transfer screen is menu program 27, invoked from the card screen.

Address table

Function	Address		Function	Address
Save_CardScreen_Update	0x4E3090		Save_EmuMC_OpenMapNameToPCPath	0x4C6BD0
Save_BuildSaveFileImage	0x4E2EF0		Save_RecompressSaveFileLZSS	0x4C6E50
Save_ComputeChecksumCRC16CCITT	0x500310		Archive_LZSSCompress	0x40FE1D
Save_EmuMC_WriteFile / ReadFile	0x4C5500 / 0x4C5B00		Savemap_Clear / LoadNewGameDefaults_InitOut	0x56D9F0 / 0x56DA10
Save_EmuMC_CreateFile	0x4C4FA0		Savemap_TickGameTimeAndCountdown	0x4701B0
Save_DebugLoadSaveFileByPath_UNUSED	0x4E2DE0		ChocoboWorld_CheckChocorpgGetId	0x4C63C0

Addresses are for FF8_EN.exe (2000 PC release) as mapped in IDA (image base 0x400000).