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Detection of Single/Twin ASICs models on Game Gear
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@sverx
sverx committed Dec 19, 2022
1 parent cfec552 commit 5f4be15
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9 changes: 6 additions & 3 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -66,7 +66,7 @@ You can test your SEGA Master System and SEGA MegaDrive/Genesis (*port A only*)

### Paddle Tests

You can test your SEGA Master System (Japanese) Paddle(s) in either port. If the knob isn't rotated or paddle key is not pressed/held/released in approx 3 seconds the test will end. PAUSE will also end the test. If paddle wasn't connected when the Test Suite started, you can connect that while in the main menu and press PAUSE to restart it, to have that detected. If two paddles are connected when the Test Suite starts, paddle test will be run immediatelym but it won't be possible to leave the test.
You can test your SEGA Master System (Japanese) Paddle(s) in either port. If the knob isn't rotated or paddle key is not pressed/held/released in approx 3 seconds the test will end. PAUSE will also end the test. If paddle wasn't connected when the Test Suite started, you can connect that while in the main menu and press PAUSE to restart it, to have that detected. If two paddles are connected when the Test Suite starts, paddle test will be run immediately but it won't be possible to leave the test.

### System Info

Expand All @@ -75,7 +75,10 @@ You can read some info about your system. In detail:
* The result of a detection routine that tests if your console is a Japanese one or an 'import' one (USA/Europe).
* The result of the VDP type detection routine: first revision SEGA Master System should have a 315-5124 chip while the newer SEGA Master System II should have a 315-5246 chip. Note that this is not always true.
* The result of the TV type detection routine: either 50Hz (PAL) or 60Hz (NTSC).
* The result of a detection routine that tests if your console is a SEGA Game Gear.
* The 16-bit checksum of the first 8 KB of the console BIOS contents (only if it's not a SEGA Game Gear). This is used to identify the BIOS in the machine, and informations will be printed in the lower part of the screen.
* The result of a detection routine that tests if your console is a SEGA Game Gear (plus the result of a detection routine that tests if it's a Twin ASIC model Game Gear).
* The 16-bit checksum of the first 8 KB of the console BIOS contents. This is used to identify the BIOS in the machine, and informations will be printed in the lower part of the screen.

If "unidentified BIOS found!" is printed, please let us know here -> http://www.smspower.org/forums/

Also, pressing the DOWN key on the pad, the first 16 KB of the BIOS contents will be saved to SRAM, if your cartridge supports that (Krikzz's Master EverDrive's users will find a SAV file in their SD cards only after dumping the SRAM to SD, which happens when you load a new ROM to the cart).

187 changes: 172 additions & 15 deletions main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@
************************************************************************ */

#define MAJOR_VER 0
#define MINOR_VER 33
#define MINOR_VER 34

#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>=(b))?(a):(b))
Expand Down Expand Up @@ -81,7 +81,9 @@ unsigned char cur_menu_item, main_menu_items, pointer_anim;

/* hardware tests results */
unsigned char TV_model;
bool is_MegaDrive, is_GameGear, has_BIOS_GG, is_Japanese, has_new_VDP, do_Port3E_works, CMOS_CPU;
bool is_Japanese, has_new_VDP, do_Port3E_works, has_CMOS_CPU;
bool is_MegaDrive, is_GameGear;
bool has_BIOS_GG, has_2ASIC_GG;
unsigned char some_paddle_connected;

/* VDP sprite zoom capabilities */
Expand Down Expand Up @@ -141,8 +143,149 @@ unsigned char temp_buf[TEMP_BUF_SIZE];
#define BIOS_SIZE_8K 0x20
#define BIOS_SIZE_1K 0x04

/* ******** for GameGear Twin Asic detection ************* */

#define VDP_CTRL_PORT 0xbf
#define VDP_DATA_PORT 0xbe

#define VRAM_AREA_READ_ADDRESS (0x3800+32*24*2)
#define VRAM_AREA_WRTE_ADDRESS (0x4000+VRAM_AREA_READ_ADDRESS)
#define VRAM_XFER_LENGTH_BYTES 256
#define VRAM_XFER_LENGTH_DWORDS (VRAM_XFER_LENGTH_BYTES/4)
#define VRAM_DATA_1ST_BYTE 0xAA
#define VRAM_DATA_2ND_BYTE 0x55
#define VRAM_DATA_3RD_BYTE 0x12
#define VRAM_DATA_4TH_BYTE 0xED
#define VRAM_DATA_DWORD (((unsigned long)VRAM_DATA_4TH_BYTE << 24)|((unsigned long)VRAM_DATA_3RD_BYTE << 16)|((unsigned long)VRAM_DATA_2ND_BYTE << 8)|(unsigned long)VRAM_DATA_1ST_BYTE)
#define RAM_CODE_SIZE 128

unsigned long ram_buffer[VRAM_XFER_LENGTH_DWORDS];

/* **************** [[[ CODE ]]] ************************** */

unsigned char check_VRAM_contents (void) __naked __z88dk_fastcall {
__asm
ld hl,#VRAM_AREA_READ_ADDRESS ; read from VRAM

ld c,#VDP_CTRL_PORT ; set VDP Control Port
di ; make it interrupt SAFE
out (c),l
out (c),h
ei

ld b,#VRAM_XFER_LENGTH_DWORDS
ld c,#VDP_DATA_PORT
ld l,#1 ; report error

_loopRead:
nop
nop
nop
nop

nop
nop
nop
nop ; 32 cycles wait

in a,(c)
cp #VRAM_DATA_1ST_BYTE
ret nz

nop
nop
nop
nop

nop
nop
nop
nop ; 32 cycles wait

in a,(c)
cp #VRAM_DATA_2ND_BYTE
ret nz

nop
nop
nop
nop

nop
nop
nop
nop ; 32 cycles wait

in a,(c)
cp #VRAM_DATA_3RD_BYTE
ret nz

nop
nop
nop
nop

nop
nop
nop
nop ; 32 cycles wait

in a,(c)
cp #VRAM_DATA_4TH_BYTE
ret nz

djnz _loopRead
ld l,#0 ; report OK
ret
__endasm;
}

void copy_VRAM_26 (void) __naked {
__asm
ld hl,#VRAM_AREA_WRTE_ADDRESS ; write to VRAM
ld c, #0xBF ; set VDP Control Port
di ; make it interrupt SAFE
out (c),l
out (c),h
ei ; 4

ld hl,#_ram_buffer ; 10
ld b,#VRAM_XFER_LENGTH_BYTES/2 ; 7
ld c,#0xBE ; 7 = 28 ( > 26 )
di

_loop_copy_26:
outi ; 16
jp nz,_loop_copy_26 ; 10 = 26

ld b,#VRAM_XFER_LENGTH_BYTES/2 ; 7 - the delay between halves must be an ODD number of cycles

_loop_copy_26_again:
outi ; 16
jp nz,_loop_copy_26_again ; 10 = 26

ei
ret
__endasm;
}

bool is_TwinAsic_GG (void) {
unsigned char i,count;
for (i=0;i<VRAM_XFER_LENGTH_DWORDS;i++)
ram_buffer[i]=VRAM_DATA_DWORD;

SMS_waitForVBlank();
SMS_VRAMmemset(VRAM_AREA_WRTE_ADDRESS, 0x00, VRAM_XFER_LENGTH_BYTES);

// make sure we're drawing the screen the moment we run the test
do
count=SMS_getVCount();
while ((count<64) || (count>=160));

copy_VRAM_26();
return (check_VRAM_contents());
}

unsigned int compute_BIOS_sum (void) __naked __z88dk_fastcall {
/* *************************
NOTE: this code will be copied to RAM and run from there!
Expand Down Expand Up @@ -535,17 +678,21 @@ void draw_footer_and_ver (void) {
SMS_setNextTileatXY(FOOTER_COL,FOOTER_ROW);
printf (" Model:");
if (is_MegaDrive)
printf ("Genesis/MegaDrive ");
printf ("Genesis/MegaDrive ");
else if (do_Port3E_works) {
if (has_new_VDP)
printf ("Master System II ");
printf ("Master System II ");
else
printf ("Master System ");
} else { // !do_Port3E_works
if (has_new_VDP)
printf ("Game Gear "); // no port3E support, new VDP
printf ("Master System ");
} else { // !do_Port3E_works
if (has_new_VDP) {
if (has_2ASIC_GG)
printf ("Game Gear (Twin ASICs) "); // no port3E support, new VDP, Two ASICs
else
printf ("Game Gear (Single ASIC)"); // no port3E support, new VDP, One ASIC
}
else
printf ("Mark III "); // no port3E support, old VDP
printf ("Mark III "); // no port3E support, old VDP
}

// print region
Expand Down Expand Up @@ -1033,13 +1180,19 @@ void sysinfo (void) {
printf (" MediaEnable?:%-3s ",(do_Port3E_works?"Yes":"No"));

SMS_setNextTileatXY(MENU_FIRST_COL,MENU_FIRST_ROW+5);
printf (" Z80 type?:%-4s ",(CMOS_CPU?"CMOS":"NMOS"));
printf (" Z80 type?:%-4s ",(has_CMOS_CPU?"CMOS":"NMOS"));

SMS_setNextTileatXY(MENU_FIRST_COL,MENU_FIRST_ROW+6);
if (is_GameGear)
printf (" Twin ASIC?:%-3s ",(has_2ASIC_GG?"Yes":"No"));
else
printf (" ");

SMS_setNextTileatXY(MENU_FIRST_COL,MENU_FIRST_ROW+7);
if ((!is_MegaDrive) && (do_Port3E_works)) { // if not MegaDrive and not GameGear and not Mark III
bios_sum=get_BIOS_sum(BIOS_SIZE_8K);
printf (" BIOS sum: 0x%04X ",bios_sum);
SMS_setNextTileatXY(1,MENU_FIRST_ROW+8);
SMS_setNextTileatXY(1,MENU_FIRST_ROW+9);
while (i<BIOSES_ITEMS) {
if (bios_sum==BIOSes[i].sum8k) {
printf ("%-30s",BIOSes[i].name);
Expand All @@ -1053,7 +1206,7 @@ void sysinfo (void) {
if (has_BIOS_GG) {
bios_sum=get_BIOS_sum(BIOS_SIZE_1K);
printf (" BIOS sum: 0x%04X ",bios_sum);
SMS_setNextTileatXY(1,MENU_FIRST_ROW+8);
SMS_setNextTileatXY(1,MENU_FIRST_ROW+9);
while (i<GG_BIOSES_ITEMS) {
if (bios_sum==GG_BIOSes[i].sum1k) {
printf ("%-30s",GG_BIOSes[i].name);
Expand Down Expand Up @@ -1115,19 +1268,23 @@ void main (void) {
do_Port3E_works=is_Port3E_effective(0xFFE0); // OR 0xE0 (set bits 5,6,7 to disable card/cartridge/expansion), AND 0xFF (don't enable anything else)

// detect Z80 type
CMOS_CPU=is_cmos_CPU();
has_CMOS_CPU=is_cmos_CPU();

// detect TV and console type using various means
SMS_displayOn();
TV_model=SMS_VDPType();
//has_new_VDP=newVDP();
unsigned char ZoomCapabilities=detectVDPSpriteZoomCapabilities();
is_MegaDrive=(ZoomCapabilities==SZC_ABSENT);
has_new_VDP=(ZoomCapabilities==SZC_COMPLETE);

// infer if this is a GameGear from the results of previous tests
is_GameGear=(!do_Port3E_works) && has_new_VDP;
if (is_GameGear)

// if this is a GameGear, check if it has a BIOS and if it's the older Twin ASIC model
if (is_GameGear) {
has_BIOS_GG=is_Port3E_effective(0xF7E0); // OR 0xE0 (set bits 5,6,7 to disable card/cartridge/expansion), AND 0xF7 (enable BIOS)
has_2ASIC_GG=is_TwinAsic_GG();
}

SMS_displayOff();

Expand Down

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