Support 'Base 64A' - a Taiwanese Apple II clone

[tomcw]

Spun off from #771.

Requested by @Drakepirate.

"Base 64A" is a Taiwanese Apple II clone: https://en.wikipedia.org/wiki/List_of_Apple_II_clones#Taiwan

---

My Base 64A Roms are 28K total ( D0:4K D8:4K E0:4K E8:4K F0:4K & F8:8K )
A reduced version of 12K cutting last 4k of F8 and 2k of rest of bin files partialy works but have no Applesoft prompt.

Ci.Base-64A.zip

[tomcw]

Hi Tom
Sorry to post it here, may be could be in request area...May be Can be the next clone to be implemented in Applewin? 🙄
I have the manual and extracted the ROMS from my real machine, also a friend made a discover of ROM mapping (Base has a text processor embedded) .

[tomcw]

The extended (bank-switched) ROM needs to be properly supported, eg. during start-up with a disk in the drive, there are these AN0 accesses which (from the above screenshot) should bank switch the ROM:

• D530: STA $C059
• F7FA: STA $C059

[Drakepirate]

My friend made a Base-64A emulator in GO and it's free to use, may be it can help...

https://github.com/ivanizag/apple2

[Drakepirate]

package apple2

import (
"fmt"

"github.com/ivanizag/apple2/core6502"

)

/*
Copam BASE64A adaptation.
*/

// newBase64a instantiates an apple2
func newBase64a() *Apple2 {
var a Apple2

a.Name = "Base 64A"
a.mmu = newMemoryManager(&a)
a.cpu = core6502.NewNMOS6502(a.mmu)
a.io = newIoC0Page(&a)
addApple2SoftSwitches(a.io)
addBase64aSoftSwitches(a.io)

return &a

}

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 loadBase64aRom(a *Apple2) error {
// 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, err := loadResource(filename)
	if err != nil {
		return err
	}
	for j := range romBanksBytes {
		start := (j * base64aRomWindowSize) % len(data)
		romBanksBytes[j] = append(romBanksBytes[j], data[start:start+base64aRomWindowSize]...)
	}
}

// Create banks
for j := range romBanksBytes {
	a.mmu.physicalROM[j] = newMemoryRange(0xd000, romBanksBytes[j])
}

// Start with first bank active
a.mmu.setActiveROMPage(0)

return nil

}

func addBase64aSoftSwitches(io *ioC0Page) {
// Other softswitches, not implemented but called from the ROM
io.addSoftSwitchW(0x0C, notImplementedSoftSwitchW, "80COLOFF")
io.addSoftSwitchW(0x0E, notImplementedSoftSwitchW, "ALTCHARSETOFF")

// Write on the speaker. That is a double access and should do nothing
// but works somehow on the BASE64A
io.addSoftSwitchW(0x30, func(io *ioC0Page, value uint8) {
	speakerSoftSwitch(io)
}, "SPEAKER")

// ROM pagination softswitches. They use the annunciator 0 and 1
mmu := io.apple2.mmu
io.addSoftSwitchRW(0x58, func(*ioC0Page) uint8 {
	p := mmu.getActiveROMPage()
	mmu.setActiveROMPage(p & 2)
	return 0
}, "ANN0OFF-ROM")
io.addSoftSwitchRW(0x59, func(*ioC0Page) uint8 {
	p := mmu.getActiveROMPage()
	mmu.setActiveROMPage(p | 1)
	return 0
}, "ANN0ON-ROM")
io.addSoftSwitchRW(0x5A, func(*ioC0Page) uint8 {
	p := mmu.getActiveROMPage()
	mmu.setActiveROMPage(p & 1)
	return 0
}, "ANN1OFF-ROM")
io.addSoftSwitchRW(0x5B, func(*ioC0Page) uint8 {
	p := mmu.getActiveROMPage()
	mmu.setActiveROMPage(p | 2)
	return 0
}, "ANN1ON-ROM")

}

func charGenColumnsMapBase64a(column int) int {
bit := column + 2
// Weird positions
if column == 6 {
bit = 2
} else if column == 0 {
bit = 1
}
return bit
}

[Drakepirate]

Theese are the ROM dumps of my Base 64

[ivanizag]

Hi. I have been looking at this last night.

I added support for up to four pages of ROM from $D000 to $FFFF with small changes in MemInitializeRom(), UpdatePaging() and two bits in memmode. I connected that to the softswitches for AN0 and AN1 and added the extra entry for the new clone on the UI.

I was able to boot properly and use the extra ROM features of the Base64A.

Is this approach correct? It would be OK to send a pull request?

[sicklittlemonkey]

A PR would be the easiest way to evaluate the code changes. Great work on the Go Apple2 emulator, BTW. It's excellent to have another open source option in another modern language. Cheers, Nick.

[Drakepirate]

Excellent news!

[ivanizag]

Thanks for the support! Happy to contribute.

I have submitted the PR.

[yonglak]

Great, I have a Base64A here. Using 8x 4164 drams. There might be a bug in the Basic 'SGN' command if I remember (1983?). Maybe my eproms suffered bit rot. Good well designed apple 2 clone.
Thanks for posting the roms. (Drakepirate)

[tomcw]

Closing as @ivanizag's PR #807 has been merged into master for this issue.

[tomcw]

@Drakepirate , @ivanizag - FYI there's a new AppleWin 1.29.14.0 here, which includes this update.