Initial support for the Base64A clone. Support for ROM banks

.gitignore

@@ -0,0 +1 @@
+.vscode

apple2main.go

@@ -59,6 +59,11 @@ func MainApple() *Apple2 {
 		false,
 		"shows the character map",
 	)
+	base64a := flag.Bool(
+		"base64a",
+		false,
+		"setup a Base64A clone",
+	)
 	flag.Parse()
 
 	if *dumpChars {
@@ -69,7 +74,11 @@ func MainApple() *Apple2 {
 	}
 
 	a := NewApple2(*charRomFile, *cpuClock, !*mono, *fastDisk, *panicSS)
-	a.LoadRom(*romFile)
+	if *base64a {
+		NewBase64a(a)
+	} else {
+		a.LoadRom(*romFile)
+	}
 	if *languageCardSlot >= 0 {
 		a.AddLanguageCard(*languageCardSlot)
 	}

base64a.go

@@ -0,0 +1,93 @@
+package apple2
+
+import "fmt"
+
+/*
+	Copam BASE64A adaptation.
+*/
+
+// Base64a extends an Apple2
+type Base64a struct {
+	a        *Apple2
+	romBanks [4]*memoryRange
+	romBank  uint8
+}
+
+// NewBase64a instantiates an apple2
+func NewBase64a(a *Apple2) *Base64a {
+
+	var b Base64a
+	b.a = a
+	b.loadRom()
+
+	return &b
+}
+
+const (
+	// There are 6 ROM chips. Each can have 4Kb or 8Kb. They can fill
+	// 2 or 4 banks with 2kb windows.
+	base64aRomBankSize   = 12 * 1024
+	base64aRomBankCount  = 4
+	base64aRomWindowSize = 2 * 1024
+	base64aRomChipCount  = 6
+)
+
+func (b *Base64a) loadRom() {
+	// Load the 6 PROM dumps
+	romBanksBytes := make([][]uint8, base64aRomBankCount)
+	for j := range romBanksBytes {
+		romBanksBytes[j] = make([]uint8, 0, base64aRomBankSize)
+	}
+
+	for i := 0; i < base64aRomChipCount; i++ {
+		filename := fmt.Sprintf("<internal>/BASE64A_%X.BIN", 0xd0+i*0x08)
+		data := loadResource(filename)
+		for j := range romBanksBytes {
+			start := (j * base64aRomWindowSize) % len(data)
+			romBanksBytes[j] = append(romBanksBytes[j], data[start:start+base64aRomWindowSize]...)
+		}
+	}
+
+	for j := range romBanksBytes {
+		b.romBanks[j] = newMemoryRange(0xd000, romBanksBytes[j])
+	}
+
+	// Start with first bank active
+	b.changeRomBank(0)
+
+	// Add rom soft switches. They use the annunciator 0 and 1
+	b.a.io.addSoftSwitchRW(0x58, func(*ioC0Page) uint8 {
+		b.changeRomBank(b.romBank & 2)
+		return 0
+	})
+	b.a.io.addSoftSwitchRW(0x59, func(*ioC0Page) uint8 {
+		b.changeRomBank(b.romBank | 1)
+		return 0
+	})
+	b.a.io.addSoftSwitchRW(0x5A, func(*ioC0Page) uint8 {
+		b.changeRomBank(b.romBank & 1)
+		return 0
+	})
+	b.a.io.addSoftSwitchRW(0x5B, func(*ioC0Page) uint8 {
+		b.changeRomBank(b.romBank | 2)
+		return 0
+	})
+
+	// Other softswitches
+	b.a.io.addSoftSwitchW(0x0C, notImplementedSoftSwitchW) // 80 columns off?
+	b.a.io.addSoftSwitchW(0x0E, notImplementedSoftSwitchW) // Alt char off?
+
+	// Write on the speaker. That is a double access and should do nothing
+	// but works somehow on the BASE64A
+	b.a.io.addSoftSwitchW(0x30, func(io *ioC0Page, value uint8) {
+		getSpeakerSoftSwitch(io)
+	})
+
+}
+
+func (b *Base64a) changeRomBank(bank uint8) {
+	b.romBank = bank
+	fmt.Printf("Change to ROM bank #%v\n", b.romBank)
+	b.a.mmu.physicalROM = b.romBanks[b.romBank]
+	b.a.mmu.resetRomPaging() // If rom was not active. This is going to far?
+}

core6502/execute.go

@@ -27,7 +27,7 @@ const (
 
 type opcode struct {
 	name        string
-	bytes       uint8
+	bytes       uint16
 	cycles      int
 	addressMode int
 	action      opFunc
@@ -54,14 +54,14 @@ func (s *State) ExecuteInstruction(log bool) {
 	}
 
 	line := make([]uint8, opcode.bytes)
-	for i := uint8(0); i < opcode.bytes; i++ {
+	for i := uint16(0); i < opcode.bytes; i++ {
 		line[i] = s.mem.Peek(pc)
 		pc++
 	}
 	s.reg.setPC(pc)
 
 	if log {
-		fmt.Printf("%#04x %-12s: ", pc, lineString(line, opcode))
+		fmt.Printf("%#04x %-12s: ", pc-opcode.bytes, lineString(line, opcode))
 	}
 	opcode.action(s, line, opcode)
 	s.cycles += uint64(opcode.cycles)

ioC0Page.go

@@ -65,16 +65,16 @@ func (p *ioC0Page) addSoftSwitchRW(address uint8, ss softSwitchR) {
 }
 
 func (p *ioC0Page) addSoftSwitchR(address uint8, ss softSwitchR) {
-	if p.softSwitchesR[address] != nil {
-		fmt.Printf("Addresss 0x0c%02x is already assigned for read", address)
-	}
+	//if p.softSwitchesR[address] != nil {
+	//	fmt.Printf("Addresss 0x0c%02x is already assigned for read\n", address)
+	//}
 	p.softSwitchesR[address] = ss
 }
 
 func (p *ioC0Page) addSoftSwitchW(address uint8, ss softSwitchW) {
-	if p.softSwitchesW[address] != nil {
-		fmt.Printf("Addresss 0x0c%02x is already assigned for write", address)
-	}
+	//if p.softSwitchesW[address] != nil {
+	//	fmt.Printf("Addresss 0x0c%02x is already assigned for write\n", address)
+	//}
 	p.softSwitchesW[address] = ss
 }
 
@@ -91,7 +91,6 @@ func (p *ioC0Page) setSpeakerProvider(s SpeakerProvider) {
 }
 
 func (p *ioC0Page) peek(address uint16) uint8 {
-	//fmt.Printf("Peek on $%02x\n", address)
 	pageAddress := uint8(address)
 	ss := p.softSwitchesR[pageAddress]
 	if ss == nil {
@@ -100,7 +99,9 @@ func (p *ioC0Page) peek(address uint16) uint8 {
 		}
 		return 0
 	}
-	return ss(p)
+	value := ss(p)
+	//fmt.Printf("Peek on $%02x: $%02x\n", address, value)
+	return value
 }
 
 func (p *ioC0Page) poke(address uint16, value uint8) {

softSwitches2.go

@@ -76,6 +76,10 @@ func addApple2SoftSwitches(io *ioC0Page) {
 func notImplementedSoftSwitchR(*ioC0Page) uint8 {
 	return 0
 }
+
+func notImplementedSoftSwitchW(*ioC0Page, uint8) {
+}
+
 func getStatusSoftSwitch(ioFlag uint8) softSwitchR {
 	return func(io *ioC0Page) uint8 {
 		return io.softSwitchesData[ioFlag]
@@ -107,11 +111,15 @@ func getKeySoftSwitch(io *ioC0Page) uint8 {
 			io.softSwitchesData[ioDataKeyboard] = key + (1 << 7)
 		}
 	}
-	return io.softSwitchesData[ioDataKeyboard]
+	value := io.softSwitchesData[ioDataKeyboard]
+	//fmt.Printf("Key $%02x, %v\n", value, strobed)
+	return value
+
 }
 
 func strobeKeyboardSoftSwitch(io *ioC0Page) uint8 {
 	result := io.softSwitchesData[ioDataKeyboard]
+	//fmt.Printf("Strobe $%02x\n", result)
 	io.softSwitchesData[ioDataKeyboard] &^= 1 << 7
 	return result
 }