- [NEW] Afegits varios documents útils recopilats.

- [NEW] Afegida la rom de Combat.
- [NEW] Afegit mòdul "rom"
- [NEW] Ampliats stubs de "mem", "tia" i "pia"

docs/bankswitching.txt

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+From: https://forums.atariage.com/topic/192418-mirrored-memory/
+
+There are two bankswitching schemes commonly called 3E and 3F because those
+zero-page addresses are used as hotspots to trigger a bank switch. The original
+version was 3F, also called Tigervision because it was used by Tigervision, and
+there is an extended version of 3F, as well as 3E. (I'm no expert on these
+schemes, so this information may contain errors.) I'm not sure if extended 3F
+and 3E are the same, or separate schemes, but 3E adds extra RAM, whereas 3F and
+extended 3F don't necessarily add extra RAM.
+
+Anyway, these bankswitching schemes divide the 4K cartridge area into two 2K
+slots. The upper 2K area ($1800 - $1FFF) always points to the last 2K of the
+cartridge ROM, but the lower 2K area ($1000 - $17FF) can be selected from
+several 2K banks by writing the desired bank number into address $3F. I think
+the original version had four 2K banks, for a total cartridge size of 8K,
+whereas the extended version allows up to 256 2K banks, for a total cartridge
+size of 512K.
+
+The 3E version still uses address $3F to select between different 2K ROM banks,
+but it also allows you to select between different 1K banks of extra RAM by
+writing the desired RAM bank number into address $3E.
+
+The TIA write addresses are $00 - $2C, and the TIA read addresses are $0 - $D,
+so even though $3E and $3F fall within the memory area that's normally
+associated with the TIA chip, they don't actually correspond to any addresses
+or mirrors that are used by the TIA read or write registers. So in theory it
+should be safe to use $3E and $3F as bankswitching hotspots without interfering
+with the TIA addresses and mirrors.
+
+However, it's my understanding that any access below $40 (i.e., from $00 - $3F)
+can trigger a bank switch in these schemes-- although this might not be true
+for all cartridges that use 3E or 3F bankswitching (I don't know). For this
+reason, the TIA addresses are usually (or always?) relocated to $40 - $7F when
+using 3E or 3F bankswitching. That is, $40 - $6C are used for the TIA write
+registers, and either $40 - $4D or $70 - $7D are used for the TIA read
+registers. Since these are mirrors of the "real" TIA addresses, accessing them
+is the same (from the TIA's point of view) as accessing $00 - $2C and $00 - $0D.