cartridge

Documentation

Overview

Package cartridge fully implements loading of mapping of cartridge memory.

There are many different types of cartridge most of which are supported by the package. Some cartridge types contain additional RAM but the main difference is how they map additional ROM to the relatively small address space available for cartridges in the VCS. This is called bank-switching. All of these differences are handled transparently by the package.

Currently supported cartridge types are listed below. The strings in quotation marks are the identifiers that should be used to specify a particular mapping in the Mapping field of cartridgeloader.Loader:

Atari 2k "2k" Atari 4k "4k" Atari 8k "F8" Atari 16k "F6" Atari 32k "F4" CBS case "FA" M-Network "E7" Parker Bros "E0" Tigervision "3F"

Index

• type Cartridge
  • func NewCartridge() *Cartridge
  • func (cart *Cartridge) Attach(cartload cartridgeloader.Loader) error
  • func (cart *Cartridge) Eject()
  • func (cart Cartridge) GetBank(addr uint16) int
  • func (cart Cartridge) GetDebugBus() bus.CartDebugBus
  • func (cart Cartridge) GetRAMbus() bus.CartRAMbus
  • func (cart Cartridge) ID() string
  • func (cart *Cartridge) Initialise()
  • func (cart *Cartridge) IsEjected() bool
  • func (cart Cartridge) Listen(addr uint16, data uint8)
  • func (cart Cartridge) NumBanks() int
  • func (cart *Cartridge) Patch(offset int, data uint8) error
  • func (cart *Cartridge) Peek(addr uint16) (uint8, error)
  • func (cart *Cartridge) Poke(addr uint16, data uint8) error
  • func (cart *Cartridge) Read(addr uint16) (uint8, error)
  • func (cart *Cartridge) RestoreState(state interface{}) error
  • func (cart *Cartridge) SaveState() interface{}
  • func (cart *Cartridge) SetBank(addr uint16, bank int) error
  • func (cart Cartridge) Step()
  • func (cart Cartridge) String() string
  • func (cart *Cartridge) Write(addr uint16, data uint8) error
• type DPCdataFetcher
• type DPCregisters
  • func (r DPCregisters) String() string
• type DPCstatic
  • func (sa DPCstatic) String() string

Types

type Cartridge

type Cartridge struct {
	bus.DebuggerBus
	bus.CPUBus

	Filename string
	Hash     string
	// contains filtered or unexported fields
}

Cartridge defines the information and operations for a VCS cartridge

func NewCartridge

func NewCartridge() *Cartridge

NewCartridge is the preferred method of initialisation for the cartridge type

func (*Cartridge) Attach

func (cart *Cartridge) Attach(cartload cartridgeloader.Loader) error

Attach the cartridge loader to the VCS and make available the data to the CPU bus

func (*Cartridge) Eject

func (cart *Cartridge) Eject()

Eject removes memory from cartridge space and unlike the real hardware, attaches a bank of empty memory - for convenience of the debugger

func (Cartridge) GetBank

func (cart Cartridge) GetBank(addr uint16) int

GetBank returns the current bank number for the specified address

Address must be a normlised cartridge address.

func (Cartridge) GetDebugBus

func (cart Cartridge) GetDebugBus() bus.CartDebugBus

GetDebugBus returns interface to the debugging bus to the cartridge.

func (Cartridge) GetRAMbus

func (cart Cartridge) GetRAMbus() bus.CartRAMbus

GetRAMbus returns an array of bus.CartRAM or nil if catridge contains no RAM

func (Cartridge) ID

func (cart Cartridge) ID() string

ID returns the cartridge mapping ID

func (*Cartridge) Initialise

func (cart *Cartridge) Initialise()

Initialise the cartridge

func (*Cartridge) IsEjected

func (cart *Cartridge) IsEjected() bool

IsEjected returns true if no cartridge is attached

func (Cartridge) Listen

func (cart Cartridge) Listen(addr uint16, data uint8)

Listen for data at the specified address.

The VCS cartridge port is wired up to all 13 address lines of the 6507. Under normal operation, the chip-select line is used by the cartridge to know when to put data on the data bus. If it's not "on" then the cartridge does nothing.

However, the option is there to "listen" on the address bus. Notably the tigervision (3F) mapping listens for address 0x003f, which is in the TIA address space. When this address is triggered, the tigervision cartridge will use whatever is on the data bus to switch banks.

func (Cartridge) NumBanks

func (cart Cartridge) NumBanks() int

NumBanks returns the number of banks in the catridge

func (*Cartridge) Patch

func (cart *Cartridge) Patch(offset int, data uint8) error

Patch writes to cartridge memory. Offset is measured from the start of cartridge memory. It differs from Poke in that respect

func (*Cartridge) Peek

func (cart *Cartridge) Peek(addr uint16) (uint8, error)

Peek is an implementation of memory.DebuggerBus. Address must be normalised.

func (*Cartridge) Poke

func (cart *Cartridge) Poke(addr uint16, data uint8) error

Poke is an implementation of memory.DebuggerBus. Address must be normalised.

func (*Cartridge) Read

func (cart *Cartridge) Read(addr uint16) (uint8, error)

Read is an implementation of memory.CPUBus. Address must be normalised.

func (*Cartridge) RestoreState

func (cart *Cartridge) RestoreState(state interface{}) error

RestoreState retuns the state of the cartridge to a previously known state

func (*Cartridge) SaveState

func (cart *Cartridge) SaveState() interface{}

SaveState notes and returns the current state of the cartridge (RAM contents, selected bank)

func (*Cartridge) SetBank

func (cart *Cartridge) SetBank(addr uint16, bank int) error

SetBank maps the specified address such that it references the specified bank. For many cart mappers this just means switching banks for the entire cartridge. Address must be normalised.

NOTE: For some cartridge types, the specific address is not important

func (Cartridge) Step

func (cart Cartridge) Step()

Step should be called every CPU cycle. The attached cartridge may or may not change its state as a result. In fact, very few cartridges care about this.

func (Cartridge) String

func (cart Cartridge) String() string

func (*Cartridge) Write

func (cart *Cartridge) Write(addr uint16, data uint8) error

Write is an implementation of memory.CPUBus. Address must be normalised.

type DPCdataFetcher

type DPCdataFetcher struct {
	Low    byte
	Hi     byte
	Top    byte
	Bottom byte

	// is the Low byte in the window between top and bottom
	Flag bool

	// music mode only used by data fetchers 4-7
	MusicMode bool
	OSCclock  bool
}

DPCdataFetcher represents a single DPC data fetcher

type DPCregisters

type DPCregisters struct {
	Fetcher [8]DPCdataFetcher

	// the current random number value
	RNG uint8
}

DPCregisters implements the bus.CartRegisters interface

func (DPCregisters) String

func (r DPCregisters) String() string

String implements the bus.CartDebugBus interface

type DPCstatic

type DPCstatic struct {
	Gfx []byte
}

DPCstatic implements the bus.CartStatic interface

func (DPCstatic) String

func (sa DPCstatic) String() string