Reverse 6 colors mod

apple2.go

@@ -19,6 +19,7 @@ type Apple2 struct {
 	softVideoSwitch *SoftVideoSwitch
 	board           string
 	isApple2e       bool
+	isFourColors    bool // An Apple II without the 6 color mod
 	commandChannel  chan command
 
 	cycleDurationNs      float64 // Current speed. Inverse of the cpu clock in Ghz

configs/_base.cfg

@@ -5,6 +5,7 @@ profile: false
 forceCaps: false
 ramworks: none
 nsc: none
+mods: 
 rgb: false
 romx: false
 chargenmap: 2e

configuration.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"os"
 	"strings"
+
+	"golang.org/x/exp/slices"
 )
 
 const configSuffix = ".cfg"
@@ -28,6 +30,7 @@ const (
 	confForceCaps = "forceCaps"
 	confRgb       = "rgb"
 	confRomx      = "romx"
+	confMods      = "mods"
 	confS0        = "s0"
 	confS1        = "s1"
 	confS2        = "s2"
@@ -204,6 +207,7 @@ func getConfigurationFromCommandLine() (*configuration, string, error) {
 		confCharRom:   "rom file for the character generator",
 		confCpu:       "cpu type, can be '6502' or '65c02'",
 		confSpeed:     "cpu speed in Mhz, can be 'ntsc', 'pal', 'full' or a decimal nunmber",
+		confMods:      "comma separated list of mods applied to the board, available mods are 'shift', 'four-colors",
 		confRamworks:  "memory to use with RAMWorks card, max is 16384",
 		confNsc:       "add a DS1216 No-Slot-Clock on the main ROM (use 'main') or a slot ROM",
 		confTrace:     "trace CPU execution with one or more comma separated tracers",
@@ -221,10 +225,6 @@ func getConfigurationFromCommandLine() (*configuration, string, error) {
 		confS7:        "slot 7 configuration.",
 	}
 
-	stringParams := []string{
-		confRom, confCharRom, confCpu, confSpeed, confRamworks, confNsc, confTrace, confModel,
-		confS0, confS1, confS2, confS3, confS4, confS5, confS6, confS7,
-	}
 	boolParams := []string{confProfile, confForceCaps, confRgb, confRomx}
 
 	configuration, err := configurationModels.getFromModel(defaultConfiguration)
@@ -233,20 +233,16 @@ func getConfigurationFromCommandLine() (*configuration, string, error) {
 	}
 	configuration.set(confModel, defaultConfiguration)
 
-	for _, name := range stringParams {
+	for name, description := range paramDescription {
 		defaultValue, ok := configuration.getHas(name)
 		if !ok {
 			return nil, "", fmt.Errorf("default value not found for %s", name)
 		}
-		flag.String(name, defaultValue, paramDescription[name])
+		if slices.Contains(boolParams, name) {
-	}
+			flag.Bool(name, defaultValue == "true", description)
-
+		} else {
-	for _, name := range boolParams {
+			flag.String(name, defaultValue, description)
-		defaultValue, ok := configuration.getHas(name)
-		if !ok {
-			return nil, "", fmt.Errorf("default value not found for %s", name)
 		}
-		flag.Bool(name, defaultValue == "true", paramDescription[name])
 	}
 
 	flag.Usage = func() {

frontend/a2sdl/sdlKeyboard.go

@@ -124,11 +124,15 @@ func (k *sdlKeyboard) putKey(keyEvent *sdl.KeyboardEvent) {
 	case sdl.K_F12:
 		fallthrough
 	case sdl.K_PRINTSCREEN:
-		err := screen.SaveSnapshot(k.a, screen.ScreenModeNTSC, "snapshot.png")
+		if ctrl {
-		if err != nil {
+			screen.AddScenario(k.a, "../../screen/test_resources/")
-			fmt.Printf("Error saving snapshoot: %v.\n.", err)
 		} else {
-			fmt.Println("Saving snapshot 'snapshot.png'")
+			err := screen.SaveSnapshot(k.a, screen.ScreenModeNTSC, "snapshot.png")
+			if err != nil {
+				fmt.Printf("Error saving snapshoot: %v.\n.", err)
+			} else {
+				fmt.Println("Saving snapshot 'snapshot.png'")
+			}
 		}
 	case sdl.K_PAUSE:
 		k.a.SendCommand(izapple2.CommandPauseUnpause)

memoryManager.go

@@ -117,7 +117,7 @@ func (mmu *memoryManager) accessCArea(address uint16) memoryHandler {
 }
 
 func (mmu *memoryManager) accessUpperRAMArea(address uint16) memoryHandler {
-	if mmu.altZeroPage {
+	if mmu.altZeroPage && mmu.hasExtendedRAM() {
 		// Use extended RAM
 		block := mmu.extendedRAMBlock
 		if mmu.lcAltBank && address <= addressLimitDArea {
@@ -135,14 +135,14 @@ func (mmu *memoryManager) accessUpperRAMArea(address uint16) memoryHandler {
 }
 
 func (mmu *memoryManager) getPhysicalMainRAM(ext bool) memoryHandler {
-	if ext {
+	if ext && mmu.hasExtendedRAM() {
 		return mmu.physicalExtRAM[mmu.extendedRAMBlock]
 	}
 	return mmu.physicalMainRAM
 }
 
 func (mmu *memoryManager) getVideoRAM(ext bool) *memoryRange {
-	if ext {
+	if ext && mmu.hasExtendedRAM() {
 		// The video memory uses the first extended RAM block, even with RAMWorks
 		return mmu.physicalExtRAM[0]
 	}
@@ -334,6 +334,10 @@ func (mmu *memoryManager) setExtendedRAMActiveBlock(block uint8) {
 	mmu.extendedRAMBlock = block
 }
 
+func (mmu *memoryManager) hasExtendedRAM() bool {
+	return len(mmu.physicalExtRAM) > 0
+}
+
 func (mmu *memoryManager) reset() {
 	if mmu.apple2.isApple2e {
 		// MMU UtA2e 4-14, 5-22

screen/hiRes.go

@@ -12,9 +12,9 @@ const (
 	hiResHeightMixed = 160
 )
 
-func snapshotHiRes(vs VideoSource, isSecondPage bool, light color.Color) *image.RGBA {
+func snapshotHiRes(vs VideoSource, isSecondPage bool, light color.Color, shiftSupported bool) *image.RGBA {
 	data := vs.GetVideoMemory(isSecondPage, false)
-	return renderHiRes(data, light)
+	return renderHiRes(data, light, shiftSupported)
 }
 
 func getHiResLineOffset(line int) uint16 {
@@ -26,7 +26,7 @@ func getHiResLineOffset(line int) uint16 {
 	return uint16(section*40 + outerEighth*0x80 + innerEighth*0x400)
 }
 
-func renderHiRes(data []uint8, light color.Color) *image.RGBA {
+func renderHiRes(data []uint8, light color.Color, shiftSupported bool) *image.RGBA {
 	// As described in "Undertanding the Apple II", with half pixel shifts
 	size := image.Rect(0, 0, 2*hiResWidth, hiResHeight)
 	img := image.NewRGBA(size)
@@ -37,7 +37,7 @@ func renderHiRes(data []uint8, light color.Color) *image.RGBA {
 		x := 0
 		var previousColour color.Color = color.Black
 		for _, b := range bytes {
-			shifted := b>>7 == 1
+			shifted := shiftSupported && b>>7 == 1
 			for j := uint(0); j < 7; j++ {
 				bit := (b >> j) & 1
 				colour := light

screen/snapshots.go

@@ -52,6 +52,7 @@ func snapshotByMode(vs VideoSource, videoMode uint16, screenMode int) *image.RGB
 	isSecondPage := (videoMode & VideoSecondPage) != 0
 	isAltText := (videoMode & VideoAltText) != 0
 	isRGBCard := (videoMode & VideoRGBCard) != 0
+	shiftSupported := (videoMode & VideoFourColors) == 0
 
 	var lightColor color.Color = color.White
 	if screenMode == ScreenModeGreen {
@@ -76,7 +77,7 @@ func snapshotByMode(vs VideoSource, videoMode uint16, screenMode int) *image.RGB
 	case VideoDGR:
 		snap = snapshotMeRes(vs, isSecondPage, lightColor)
 	case VideoHGR:
-		snap = snapshotHiRes(vs, isSecondPage, lightColor)
+		snap = snapshotHiRes(vs, isSecondPage, lightColor, shiftSupported)
 	case VideoDHGR:
 		snap, _ = snapshotDoubleHiRes(vs, isSecondPage, false /*isRGBMixMode*/, lightColor)
 	case VideoMono560:

screen/snapshotsDebug.go

@@ -85,6 +85,10 @@ func VideoModeName(vs VideoSource) string {
 		name += "-ALT"
 	}
 
+	if (videoMode & VideoFourColors) != 0 {
+		name += "-4COLORS"
+	}
+
 	switch mixMode {
 	case VideoMixText40:
 		name += "-MIX40"

screen/testScenarios.go

@@ -6,7 +6,6 @@ import (
 	"image"
 	"image/color"
 	"image/png"
-	"io/ioutil"
 	"os"
 	"strings"
 )
@@ -58,7 +57,7 @@ func cloneSlice(src []uint8) []uint8 {
 }
 
 func loadTestScenario(filename string) (*TestScenario, error) {
-	bytes, err := ioutil.ReadFile(filename)
+	bytes, err := os.ReadFile(filename)
 	if err != nil {
 		return nil, err
 	}
@@ -79,7 +78,7 @@ func (ts *TestScenario) save(dir string) (string, error) {
 	}
 
 	pattern := fmt.Sprintf("%v_*.json", strings.ToLower(ts.VideoModeName))
-	file, err := ioutil.TempFile(dir, pattern)
+	file, err := os.CreateTemp(dir, pattern)
 	if err != nil {
 		return "", err
 	}

screen/videoSource.go

@@ -36,6 +36,7 @@ const (
 	VideoSecondPage    uint16 = 0x1000
 	VideoAltText       uint16 = 0x2000
 	VideoRGBCard       uint16 = 0x4000
+	VideoFourColors    uint16 = 0x8000
 )
 
 // VideoSource provides the info to build the video output

setup.go

@@ -3,6 +3,7 @@ package izapple2
 import (
 	"fmt"
 	"strconv"
+	"strings"
 
 	"github.com/ivanizag/iz6502"
 )
@@ -62,6 +63,19 @@ func configure(configuration *configuration) (*Apple2, error) {
 		}
 	}
 
+	// Add mods
+	mods := strings.Split(configuration.get(confMods), ",")
+	for _, mod := range mods {
+		switch strings.TrimSpace(mod) {
+		//case "shift":
+		//	setupShiftedKeyboard(a)
+		case "four-colors":
+			// This removes the mod to have 6 colors sent by Wozniak to Byte
+			// magazine. See: https://archive.org/details/byte-magazine-1979-06/page/n67/mode/2up?view=theater
+			a.isFourColors = true
+		}
+	}
+
 	// Add optional accesories including the aux slot
 	ramWorksSize := configuration.get(confRamworks)
 	if ramWorksSize != "" && ramWorksSize != "none" {

videoSourceImpl.go

@@ -92,6 +92,9 @@ func (a *Apple2) GetCurrentVideoMode() uint16 {
 	if isRGBCard {
 		mode |= screen.VideoRGBCard
 	}
+	if a.isFourColors {
+		mode |= screen.VideoFourColors
+	}
 
 	return mode
 }