123 lines
2.9 KiB
Go
123 lines
2.9 KiB
Go
package izapple2
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/*
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Brain board II card for Apple II
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See:
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http://www.willegal.net/appleii/brainboard.htm
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http://www.willegal.net/appleii/bb-v5_3.1.pdf
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https://github.com/Alex-Kw/Brain-Board-II
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The Brain Board II card has 4 banks instead of the 2 of the
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original Brain Board:
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Bank 0: SS clear, DIP2 OFF (wozaniam)
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Bank 1: SS set, DIP2 OFF (applesoft)
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Bank 2: SS clear, DIP2 ON (wozaniam)
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Bank 3: SS set, DIP2 ON (integer)
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The card is emulated as having the DIP switches as follows:
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1 - ON: The range F8 can be replaced
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2 - ON: Select the two top banks
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3 - OFF: The motherboard ROM is always replaced
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4 - ON: The softswitch selects low or high bank
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Softswitches:
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$COsO - SS clear: Low bank selected
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$COs1 - SS set: High bank selected
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Operation:
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The card boots on wozaniam. Use CAPS LOCK for the commands
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to work. Starts with left arrow.
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To siwtch to Integer BASIC, type:
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1000:AD 91 C0 6C FC FF
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R
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To return to wozaniam, type:
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CALL -151
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1000:AD 90 C0 6C FD FF
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1000G
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*/
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// CardBrainBoardII represents a Brain Board II card
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type CardBrainBoardII struct {
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cardBase
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highBank bool
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dip2 bool
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rom []uint8
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pages int
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forceBank int
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}
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const noForceBank = -1
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func newCardBrainBoardIIBuilder() *cardBuilder {
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return &cardBuilder{
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name: "Brain Board II",
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description: "Firmware card. It has up to four ROM banks",
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defaultParams: &[]paramSpec{
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{"rom", "ROM file to load", "<internal>/ApplesoftInteger.BIN"},
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{"dip2", "Use the upper half of the ROM", "true"},
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{"bank", "Force a ROM bank, 'no' or bank number", "no"}},
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buildFunc: func(params map[string]string) (Card, error) {
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var c CardBrainBoardII
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var err error
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c.highBank = false // Start with wozaniam by default
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c.dip2 = paramsGetBool(params, "dip2")
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c.forceBank, err = paramsGetInt(params, "bank")
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if err != nil {
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c.forceBank = noForceBank
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}
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// The ROM has:xaa-wozaniam xab-applesoft xac-wozaniam xad-integer
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romFile := paramsGetPath(params, "rom")
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data, _, err := LoadResource(romFile)
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if err != nil {
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return nil, err
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}
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c.pages = len(data) / 0x4000
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c.rom = data
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c.romCxxx = &c
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return &c, nil
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},
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}
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}
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func (c *CardBrainBoardII) assign(a *Apple2, slot int) {
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c.addCardSoftSwitchRW(0, func() uint8 {
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c.highBank = false
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return 0x55
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}, "BRAINCLEAR")
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c.addCardSoftSwitchRW(1, func() uint8 {
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c.highBank = true
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return 0x55
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}, "BRAINSET")
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c.cardBase.assign(a, slot)
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a.mmu.inhibitROM(c)
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}
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func (c *CardBrainBoardII) translateAddress(address uint16) uint16 {
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var bank = 0
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if c.forceBank != noForceBank {
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bank = c.forceBank
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} else {
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bank = 0
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if c.highBank {
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bank += 1
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}
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if c.dip2 {
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bank += 2
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}
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}
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return address - 0xc000 + uint16(bank*0x4000)
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}
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func (c *CardBrainBoardII) peek(address uint16) uint8 {
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return c.rom[c.translateAddress(address)]
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}
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func (c *CardBrainBoardII) poke(address uint16, value uint8) {
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// Nothing
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}
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