Porting kegs-universal changes to gsplus. #31

leonbottou · 2018-07-03T16:59:56Z

This is the gsplus version of the kegs-universal changes. These changes allow kegs (and now gsplus) to operate using all classic apple 2 roms. See https://github.com/leonbottou/kegs-universal. The supported roms include:

Apple 2 and Apple 2+ roms (12KB)
Apple 2e roms (regular and enhanced, 16KB)
Apple 2c and 2c+ roms (all five version).

The idea is to add just what's necessary to operate these older roms. The emulated machine essentially remains a 2gs, but with the minimal changes necessary to operate the selected rom. Most of the changes are in file moremem.c to support the necessary io-space features of each of these computers. Smaller related changes have been made to adb.c, config.c, defs_instr.c, iwm.c, sim68516.c, and smartport.c. (see https://github.com/leonbottou/kegs-universal/blob/master/README.md for details). Some of these changes actually improve the 2gs emulation (e.g. the language card double reads, the phantom read with instruction INC abs,X, the slot powerup scan,...

Despite all these changes, the diff remains readable and explainable. I am intending to add comments to all these diffs to explain what they do and make the review easier.

leonbottou · 2018-07-03T17:01:30Z

doc/kegs-universal.md

@@ -0,0 +1,179 @@
+# kegs-universal


This is merely a copy of the kegs-universal README file.

leonbottou · 2018-07-03T17:02:36Z

src/.dir-locals.el

@@ -0,0 +1,9 @@
+;;; Directory Local Variables


This lets emacs uses tabs in the same way as the rest of the kegs codebase.

leonbottou · 2018-07-03T17:04:26Z

src/adb.c

@@ -1257,7 +1258,10 @@ update_mouse(int x, int y, int button_states, int buttons_valid)
 		if( (g_mouse_ctl_addr == g_mouse_dev_addr) &&
 						((g_adb_mode & 0x2) == 0)) {
 			g_adb_mouse_valid_data = 1;
-			adb_add_mouse_int();


Changes the mouse interrupt behavior when using an Apple2c rom. (see comment in code)

leonbottou · 2018-07-03T17:09:27Z

src/adb.c

@@ -1267,6 +1271,13 @@ update_mouse(int x, int y, int button_states, int buttons_valid)
 int
 mouse_read_c024(double dcycs)
 {
+	return mouse_read_c024_clamp(dcycs, 0x3f);
+}
+


The apple2c mouse i/o ports in moremem.c call this function with clamp=2 in order to obtain detailed mouse position updates instead of aggregated updates in range -0x3f,+0x3f like a 2gs.

leonbottou · 2018-07-03T17:09:34Z

src/config.c

@@ -58,6 +58,7 @@ extern byte *g_rom_fc_ff_ptr;
 extern byte *g_rom_cards_ptr;
 extern double g_cur_dcycs;
 extern int g_rom_version;
+extern int g_a2rom_version;


The detected apple 2 rom version. Values are '2', 'e', 'c', 'C', and 'g' for the apple2/2+, apple2e, apple2c, apple2c+, and apple2gs respectively.

leonbottou · 2018-07-03T17:12:06Z

src/config.c

 char *g_cfg_file_def_name = "Undefined";
 char **g_cfg_file_strptr = 0;
-int g_cfg_file_min_size = 1024;
+int g_cfg_file_min_size = 256;


This allows the file selection dialog to select files that are only 256 bytes long. Usefull for the c600 rom.

leonbottou · 2018-07-03T17:13:28Z

src/config.c

@@ -228,6 +230,7 @@ Cfg_menu g_cfg_joystick_menu[] = {
 Cfg_menu g_cfg_rom_menu[] = {
 { "ROM File Selection", g_cfg_rom_menu, 0, 0, CFGTYPE_MENU },
 { "ROM File", KNMP(g_cfg_rom_path), CFGTYPE_FILE },
+{ "C600 ROM File", KNMP(g_cfg_c6rom_path), CFGTYPE_FILE },


New rom selection entry to provide a c600 rom. This is critical for the 2, 2+, 2e models because the main rom does not contain the disk 2 boot rom.

leonbottou · 2018-07-03T17:14:09Z

src/config.c

-	} else {
-		fatal_printf("The ROM size should be 128K or 256K, this file "
-						"is %d bytes\n", len);
+ 	} else if(len == 12*1024) { /* ][ and II+ */


What follows loads 12KB, 16KB, and 32KB rom files.

leonbottou · 2018-07-03T17:15:05Z

src/config.c

@@ -879,22 +906,57 @@ config_load_roms()
 	}
 	fclose(file);

-	memset(&g_rom_cards_ptr[0], 0, 256*16);
+	/* Detect A2 roms */


And this detects what kind of rom has been loaded using the official method.

leonbottou · 2018-07-03T17:15:58Z

src/config.c

+        /* Slot roms */
+	memset(&g_rom_cards_ptr[0], 0, 256*16);
+	/* Initialize c600 rom to be diffs from the real ROM, to build-in */
+	/* Apple II compatibility without distributing ROMs */


These diffs only apply to the 2gs roms. Other model (except the 2c) need a c600 rom file.

leonbottou · 2018-07-03T17:18:12Z

src/config.c

-
+	/* Initialize c700 rom for smartport */
+        switch(g_a2rom_version) {
+        case 'g': case '2': case 'e':


The slot 7 smartport slot rom has been reduced to its simplest expression. All bytes are zero except those that tell the firmware or the operating system that there is a smartport compatible device in slot 7.

leonbottou · 2018-07-03T17:19:11Z

src/config.c

@@ -915,6 +977,7 @@ config_load_roms()

 			len = 256;
 			ret = fread(&g_rom_cards_ptr[i*0x100], 1, len, file);
+			fclose(file);


That was a bug in the existing gsplus code. The file would not have been closed if the read had failed (see continue below).

leonbottou · 2018-07-03T17:22:37Z

src/config.c

@@ -1592,7 +1654,12 @@ insert_disk(int slot, int drive, const char *name, int ejected, int force_size,
 			}
 		}
 	}
-
+	if (! dsk->smartport && ! dsk->disk_525) {


Formatting a 3.5 inch floppy on an apple 2c+ gives a 1:4 interleaved disk instead of a 1:2 interleaved disk. They did that to accommodate the slower processor (all disk i/o is performed at 1Mhz on the 2c+). Disk images with suffix .po4 loaded a 3.5 inch drive are assumed to have 1:4 interleave.

leonbottou · 2018-07-03T17:24:08Z

src/defs_instr.h

@@ -637,9 +637,12 @@ defs_instr_start_16	.word	0
 #  define GET_ABS_X_RD_WR()					\
 	GET_2BYTE_ARG;						\
 	INC_KPC_3;						\
-	CYCLES_PLUS_2;						\


It turns out that some code relies on the fact that instruction INC abs,X performs a phantom read before reading the actual data. This is often used to double read the language card write enable i/o port. I have implemented this in the C emulation but not the PowerPC assembly version (no way to test).

leonbottou · 2018-07-03T17:25:29Z

src/iwm.c

@@ -507,14 +507,15 @@ iwm_touch_switches(int loc, double dcycs)
 			break;
 		case 0xa:
 		case 0xb:
-			iwm.drive_select = on;
+			iwm.drive_select = mig_changedrive(on);


This is used to map the Apple2c+ 3.5 drives to the 2gs drives (see long comment in moremem.c)

leonbottou · 2018-07-03T17:26:24Z

src/iwm.c

 			break;
 		case 0xc:
 		case 0xd:
 			iwm.q6 = on;
 			break;
 		case 0xe:
 		case 0xf:
+			mig_checkwhead(dsk, on); 


And this is useful because the 2c+ formatting firmware does not switch heads using the official method but using an undocumented method.

leonbottou · 2018-07-03T17:26:54Z

src/iwm.c

@@ -2007,7 +2008,7 @@ iwm_nibblize_track_35(Disk *dsk, Trk *trk, byte *track_buf, int qtr_track)
 	}

 	phys_sec = 0;
-	interleave = 2;
+	interleave = (dsk->image_type == DSK_TYPE_35_4) ? 4 : 2;


Implements 1:4 interleaving for disk images of this new type. Only 3.5 inch floppy images are concerned.

leonbottou · 2018-07-03T17:27:28Z

src/iwm.h

@@ -30,6 +30,9 @@
 #define DSK_TYPE_PRODOS		0
 #define DSK_TYPE_DOS33		1
 #define DSK_TYPE_NIB		2
+#define DSK_TYPE_35_4    	4   /* 3.5 disk with 1:4 interleave */


The new type of disk image, for 1:4 interleaved 3.5 floppy disks.

leonbottou · 2018-07-03T17:30:10Z

src/sim65816.c

@@ -756,11 +758,31 @@ do_reset()
 	extern	int g_scan_int_events ;
 	extern int g_c023_val;

-	g_c068_statereg = 0x08 + 0x04 + 0x01; /* rdrom, lcbank2, intcx */
-	g_c035_shadow_reg = 0;


Reset does not initialize the hardware in the same way. The 2 and 2+ do not reset the language card at all. The 2,2+ and 2e have all slots enabled. The 2c has none. All must slow down to 1Mhz when the disk motor is on.

leonbottou · 2018-07-03T17:31:07Z

src/sim65816.c

@@ -1704,7 +1726,8 @@ run_prog()
 			setup_zip_speeds();
 		}

-		iwm_1 = motor_on && !apple35_sel &&


The 2gs firmware for 3.5 inch floppy drives runs at 2.8Mhz. All others run this at 1Mhz.

leonbottou · 2018-07-03T17:33:13Z

src/sim65816.c

@@ -1922,11 +1945,7 @@ take_irq(int is_it_brk)
 			/* Clear B bit in psr on stack */
 		engine.stack = ((engine.stack -1) & 0xff) + 0x100;



The remaining code deals with an oddity of the 2gs. On the 2gs, a special circuitry forces the processor to read the interrupt vectors in bank $ff (instead of bank $00 if the processor was left to itself). We must do this only for the 2gs because the other models also have interrupt vectors in the language card...

leonbottou · 2018-07-03T17:35:10Z

src/smartport.c

-		engine.kpc = 0xc764;
-	} else {
-		engine.kpc = 0xc765;
-	}


Instead of relying on a known RTS in the rom image, the prodos handler for the slot 7 smartport returns by reading the return address from the stack (just like the smartport mli handler in fact.) This was necessary to run the hard disk on an apple2e for instance.

leonbottou · 2018-07-03T17:36:29Z

src/moremem.c

@@ -413,6 +664,8 @@ fixup_intcx()
 				rom_inc = SET_BANK_IO;
 				if(((g_c02d_int_crom & mask) == 0) || INTCX) {
 					rom_inc = rom10000 + (j << 8);


The following change (and similar changes below) implement the ROMBANK bit in the state register.

leonbottou · 2018-07-03T17:37:32Z

src/moremem.c

@@ -427,6 +680,12 @@ fixup_intcx()
 			if(((g_c02d_int_crom & (1 << 3)) == 0) || INTCX) 
 			{				
 				rom_inc = rom10000 + (j << 8);
+ 				if(g_c068_statereg & 0x02) {
+ 					if((g_a2rom_version == 'C') && (j >= 0xce))
+ 						rom_inc = SET_BANK_IO; /* mig */


The MIG chip on the apple2c is mapped at addresses CE00-CFFF of the alternate rom bank.

leonbottou · 2018-07-03T17:39:30Z

src/moremem.c

-	}
-	fixup_brks();
+ 		if ((g_c02d_int_crom & 0x80) && !INTCX) {
+ 			SET_PAGE_INFO_RD(0xc7, SET_BANK_IO); /* smartport */


The slot7 smart port is now implemented as a slot rom. Therefore it can be enabled or disabled by enabling or disabling the slot7 card. And it can also work on the apple2+ or apple2e.

leonbottou · 2018-07-03T17:40:03Z

src/moremem.c

+ 		}
+  	}
+  	fixup_brks();
+ 	fixup_mig();


This is because the apple 2c+ mig chip is reset whenever one returns to the main rom bank.

leonbottou · 2018-07-03T17:40:26Z

src/moremem.c

@@ -571,6 +833,8 @@ fixup_altzp()
 		}
 		if(rdrom) {
 			mem0rd = &(g_rom_fc_ff_ptr[0x3d000]);
+			if((g_c068_statereg & 0x02) && A2CROM)
+				mem0rd -= 0x10000;


Alternate rom bank again

leonbottou · 2018-07-03T17:40:50Z

src/moremem.c

@@ -835,11 +1105,17 @@ set_statereg(double dcycs, int val)

 	if(_xor & 0x02) {
 		/* ROMBANK */
-		halt_printf("Just set rombank = %d\n", ROMB);


Implement the ROMBANK bit of the state register

leonbottou · 2018-07-03T17:41:24Z

src/moremem.c

-			return(adb_read_c000());
-
+		case 0x0c: case 0x0d: case 0x0e: case 0x0f: {
+			int c = adb_read_c000();


The apple2 keyboard has only uppercase letters

leonbottou · 2018-07-03T17:43:51Z

src/moremem.c

@@ -1246,15 +1529,27 @@ io_read(word32 loc, double *cyc_ptr)
 		case 0x14: /* c014=rdramwrt */
 			return IOR(RAMWRT);
 		case 0x15: /* c015 = INTCX */
-			return IOR(INTCX);


The 2c and 2c+ iou chip is in fact different from the 2e or mega2 versions. All these differences are enabled by macro A2CROM which tests whether g_a2rom_version is 'c' or 'C'. The are much more differences than I expected.

leonbottou · 2018-07-03T17:45:29Z

src/moremem.c

@@ -1289,18 +1584,15 @@ io_read(word32 loc, double *cyc_ptr)
 		case 0x27: /* 0xc027 */
 			return adb_read_c027();
 		case 0x28: /* 0xc028 */
-			UNIMPL_READ;


c028 switches the alternate rom bank.

leonbottou · 2018-07-03T17:47:05Z

src/moremem.c

+		case 0x4c: /* 0xc04c */
+		case 0x4d: /* 0xc04d */
+		case 0x4e: /* 0xc04e */
+			g_a2c_mouse &= 0xf3;


Clear 2c mouse data. Note that g_a2c_mouse can only be non zero when A2CROM is true.

leonbottou · 2018-07-03T17:49:27Z

src/moremem.c

 				g_cur_a2_stat &= (~ALL_STAT_ANNUNC3);
-				change_display_mode(dcycs);


When setting double hires, only change the display mode when the bit is actually changed.

leonbottou · 2018-07-03T17:51:41Z

src/moremem.c

 		/* 0xc080 - 0xc08f */
 		case 0x80: case 0x81: case 0x82: case 0x83:
 		case 0x84: case 0x85: case 0x86: case 0x87:
 		case 0x88: case 0x89: case 0x8a: case 0x8b:
 		case 0x8c: case 0x8d: case 0x8e: case 0x8f:
+			/* After checkingthe Language Card schematics */


The kegs language card emulation was imperfect. I checked the language card schematics to get it exactly right (and in particular get the double-read aspect correct). And I fixed the emulator to implement the phantom read that some code uses to double-read the language card toggle...

leonbottou · 2018-07-03T17:53:52Z

src/moremem.c

@@ -1656,7 +1999,20 @@ io_read(word32 loc, double *cyc_ptr)
 #endif

 		/* 0xc0c0 - 0xc0cf */
-		case 0xc0: case 0xc1: case 0xc2: case 0xc3:


Some apple2c roms hang when the ram extension card (the "slinky" card) is not emulated. They only work in the real machine because the floating bus eventually returns what the firmware expects.

leonbottou · 2018-07-03T17:54:32Z

src/moremem.c

@@ -1668,10 +2024,13 @@ io_read(word32 loc, double *cyc_ptr)
 		case 0xdc: case 0xdd: case 0xde: case 0xdf:
 			return 0;
 		/* 0xc0e0 - 0xc0ef */
+		case 0xe8: case 0xe9:


Intercept the drive motor change to correctly remap the a2c+ 3.5 drives to the kegs ones.

leonbottou · 2018-07-03T17:55:25Z

src/moremem.c

@@ -1694,19 +2053,17 @@ io_read(word32 loc, double *cyc_ptr)
 		}
 		return float_bus(dcycs);
 	case 7:
-		/* c700 */


All this is now useless because we implement the slot 7 smartport as a slot card.

leonbottou · 2018-07-03T17:56:05Z

src/moremem.c

@@ -1881,6 +2238,9 @@ io_write(word32 loc, int val, double *cyc_ptr)
 		case 0x27: /* 0xc027 */
 			adb_write_c027(val);
 			return;
+		case 0x28: /* 0xc028 */


Writing to c028 is the official way to swap the rom bank on a 2c. Reading works too.

leonbottou · 2018-07-03T17:57:03Z

src/moremem.c

@@ -2036,6 +2395,8 @@ io_write(word32 loc, int val, double *cyc_ptr)
 			return;

 		/* 0xc040 - 0xc04f */


Reordered the c04x writes in a manner that makes a bit more sense.

leonbottou · 2018-07-03T17:58:53Z

src/moremem.c

-			if(g_zipgs_unlock < 4) {
+			if(g_zipgs_unlock >= 4) {
+				/* nothing */
+			} else if(g_a2c_ioudis) {


g_a2c_ioudis can only be false when using an apple2c/2c+ rom.

leonbottou · 2018-07-03T18:02:09Z

src/moremem.c

 				g_c05x_annuncs |= 1;
+			} else {


Clear mouse interrupt (only the 2c/2c+ gets there because g_a2c_ioudis is always 1 with other roms.

leonbottou · 2018-07-03T18:03:26Z

src/moremem.c

@@ -2400,7 +2770,24 @@ io_write(word32 loc, int val, double *cyc_ptr)
 #endif

 		/* 0xc0c0 - 0xc0cf */
-		case 0xc0: case 0xc1: case 0xc2: case 0xc3:
+		case 0xc0: case 0xc1: case 0xc2:


2c ram extension emulation (slinky)

leonbottou · 2018-07-03T18:04:10Z

src/moremem.c

@@ -2414,9 +2801,12 @@ io_write(word32 loc, int val, double *cyc_ptr)
 			UNIMPL_WRITE;

 		/* 0xc0e0 - 0xc0ef */
+		case 0xe8: case 0xe9: 


intercept drive motor switch to correctly map 2c+ drives to kegs drives

leonbottou · 2018-07-03T18:04:59Z

src/moremem.c

-	case 8: case 9: case 0xa: case 0xb: case 0xc: case 0xd: case 0xe:
+	case 9: case 0xa: case 0xb: case 0xd: 
+		UNIMPL_WRITE;
+	case 0x8: case 0xc: case 0xe:


MIG responds to writes to c8XX ccXX and ceXX in the alternate rom bank

mgcaret · 2018-07-03T21:21:53Z

I'd like to personally "thumbs up" these patches. While the resulting emulations are not quite true-to-form, resulting in a "super" version of the emulated systems, I have been exercising kegs-universal for some time now and the patches are solid. To date, these patches contain the only working emulation of the Apple IIc Plus MIG chip, when combined with the KEGS IWM/3.5 drive emulation, allow KEGS to fully emulate the Apple IIc Plus.

MG

leonbottou · 2018-07-04T04:05:56Z

src/smartport.c

@@ -786,6 +787,12 @@ do_c700(word32 ret)

 	if(ret != 0) {
 		printf("Failure reading boot disk in s7d1!\n");
-		engine.kpc = 0xff59;	/* Jump to monitor, fix $36-$39 */


If there is no boot sector, continue scanning the remaining slots. This is done in the "standard way", that is by testing whether 00,01 contain the jump vector used by the powerup monitor code. Otherwise jump into monitor mode (the old A2 reset vector.)

digarok · 2019-08-16T19:13:17Z

Can not merge. Source is divergent with many conflicts at this point. My fault. Sorry.

leonbottou · 2019-08-16T19:36:07Z

Yep. At this point, this is cooked...

sicklittlemonkey · 2020-11-04T00:05:15Z

Only just made aware of this. Fantastic work, and a great pity it wasn't integrated.

leonbottou · 2021-01-12T21:01:16Z

I could port the changes again. This is a lot of manual work. I wouldn't want to do it just to see the request linger until they un-mergeable again. Note that https://github.com/leonbottou/kegs-universal works fine but lacks many of the gsplus features.

leonbottou added 2 commits July 3, 2018 13:52

ported diffs from xkegs-universal

296d3e0

added kegs-universal doc file

e43af2d

leonbottou commented Jul 3, 2018

View reviewed changes

doc/kegs-universal.md

@@ -0,0 +1,179 @@

# kegs-universal

Copy link

Author

leonbottou Jul 3, 2018

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This is merely a copy of the kegs-universal README file.

leonbottou commented Jul 3, 2018

View reviewed changes

leonbottou commented Jul 4, 2018

View reviewed changes

leonbottou added 2 commits July 4, 2018 08:37

Fixed moremem_init (bad initial value in c068)

047e1ec

Added menu entry for parallel rom

e3544d6

digarok closed this Aug 16, 2019

webspacecreations mentioned this pull request Oct 7, 2020

Best path forward? linappleii/linapple#150

Open

		@@ -1922,11 +1945,7 @@ take_irq(int is_it_brk)
		/* Clear B bit in psr on stack */
		engine.stack = ((engine.stack -1) & 0xff) + 0x100;

		g_cur_a2_stat &= (~ALL_STAT_ANNUNC3);
		change_display_mode(dcycs);

		@@ -2036,6 +2395,8 @@ io_write(word32 loc, int val, double *cyc_ptr)
		return;

		/* 0xc040 - 0xc04f */

Porting kegs-universal changes to gsplus. #31

Porting kegs-universal changes to gsplus. #31

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digarok commented Aug 16, 2019

leonbottou commented Aug 16, 2019

sicklittlemonkey commented Nov 4, 2020

leonbottou commented Jan 12, 2021

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