Difference between revisions of "Sega G80 Hardware Reference (1997-10-25)"
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This is a copy of an "unofficial" document containing original research, for use as a source on Sega Retro. This page likely exists for historical purposes - the contents should ideally be copy-edited and wikified to make better use of Sega Retro's software. Original source: http://web.archive.org/web/20120219195401/www.cityofberwyn.com/simulation/gameHardware/G80ref1.20.txt |
Sega G80 Hardware Reference Version 1.20 25 Oct 1997 Main Processor: Z80 at 3.86712 MHz (vector games) Z80 at 8.00000 MHz (raster games) Sound Processor: 8035 Test button on CPU board asserts NMI 40Hz interrupt from vector timing board There is an 8*8 hardware multiplier on the XY control board Memory Map 0000 - 07FF 2k ROM on CPU board (power on diagnostics) 0800 - BFFF 46k ROM board C800 - CFFF 2k RAM on CPU board D000 - DFFF downloadable RAM on universal sound board E000 - EFFF 4k Vector RAM E000 - E3FF Raster screen RAM E800 - EFFF Raster character RAM (bit 1) F000 - F03F Raster color RAM F040 - F07F Raster background color RAM (Monster Bash) F800 - FFFF Raster character RAM (bit 2) ------------------------------- I/O INPUT PORTS ------------------------------- Tac/Scan, Star Trek, and Zektor read either the panel switches (1) or spinner (0) based on the setting of the LSB the output port at 0xf8 The value written appears to always be 0xff or 0xfe in these games. 4 Player Eliminator has an I/O expansion board to two additional control ports, and a port to sense which coin mech was activated. All of the coin inputs are logically or-ed together to activate the coin 1 input. The two added I/O ports are selected on port 0xfc based on the bits written out to port 0xf8. There is also a latch on the I/O expander board to select which lockout on the coin mech to activate from the coin mech 1 output. If bit 0x10 of port f8 is 0, it selects the latch, if it is a 1, it activates the two added input ports. Writing 0x1f selects the coin sense register, writing 0x1e selects the red and yellow player switch inputs. Input bits are active LOW, with the exception of port 0xFC where they are active HIGH. The coin input bits need to be activated with an impulse. These are timed to prevent false coin inputs. Timing adjustments can be verified on the test screens. The spinner value appears to always increment when it is rotated in either direction. If the DIR bit is 1, the spinner is spinning counter- clockwise. The dir bit changes state when the direction of rotation changes. CPU BOARD --------- 0xFC (374) NOTE: The port bits are active HIGH +---------+---------+---------+---------+---------+---------+---------+--------+ | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | +=========+=========+=========+=========+=========+=========+=========+========+ | P1-30 | P1-29 | P1-28 | P1-27 | P1-26 | P1-25 | P1-24 | P1-23 | +---------+---------+---------+---------+---------+---------+---------+--------+ |RotL P2 |RotR P2 | FIRE P2 |THRUST P2| <--- SPACE FURY (cocktail) | +---------+---------+---------+---------+---------+---------+---------+--------+ ELIMINATOR ---> |RotR Red |ThrustRed|Fire Red| +---------+---------+---------+---------+---------+---------+---------+--------+ STAR TREK ---> | WARP | PHOTON | PHASER | IMPULSE | 2Player |1Player | +---------+---------+---------+---------+---------+---------+---------+--------+ TAC/SCAN ---> | | | ADD SHIP| FIRE | 2Player |1Player | +---------+---------+---------+---------+---------+---------+---------+--------+ ZEKTOR ---> | | | THRUST | FIRE | 2Player |1Player | +---------+---------+---------+---------+---------+---------+---------+--------+ SPACE ODYSSEY ---> | | | | DOWN | LEFT | RIGHT | +---------+---------+---------+---------+---------+---------+---------+--------+ or.. +---------+---------+---------+---------+---------+---------+---------+--------+ | <------------- 7 bit count from spinner --------------> | Dir | +---------+---------+---------+---------+---------+---------+---------+--------+ on 4 player Eliminator... 0x1f output to port 0xf8 +---------+---------+---------+---------+---------+---------+---------+--------+ | | | | |Yel coin |Red coin |Grn coin |Blu coin| +---------+---------+---------+---------+---------+---------+---------+--------+ 0x1e output to port 0xf8 +---------+---------+---------+---------+---------+---------+---------+--------+ | Red L | Red R | Red Thr | Red Fire| Yel L | Yel R | Yel Thr |Yel Fire| +---------+---------+---------+---------+---------+---------+---------+--------+ 0xFB (373) NOTE: The port bits are active LOW +---------+---------+---------+---------+---------+---------+---------+--------+ | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | +=========+=========+=========+=========+=========+=========+=========+========+ | ----- | ----- | P1-17 | P1-21 | SW1-5 | SW1-1 | SW2-5 | SW2-1 | +---------+---------+---------+---------+---------+---------+---------+--------+ SPACE FURY ---> | FIRE P1 |THRUST P1| | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ ELIMINATOR ---> |Fire BLU | RotL RED| | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ ELIM 4P ---> | ROTL GRN| ROTL BLU| | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ ASTRO BLASTER ---> | Fire | Warp | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ 005 ---> | Fire | Down | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ MONSTER BASH ---> | Fire | Down | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ SPACE ODYSSEY ---> | Fire | | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ 0xFA (372) NOTE: The port bits are active LOW +---------+---------+---------+---------+---------+---------+---------+--------+ | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | +=========+=========+=========+=========+=========+=========+=========+========+ | ----- | P1-14 | P1-16 | P1-20 | SW1-6 | SW1-2 | SW2-6 | SW2-2 | +---------+---------+---------+---------+---------+---------+---------+--------+ SPACE FURY ---> | RotL P1 | RotR P1 | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ | |RotL BLU |RotR BLU |ThrustBLU| | <---- ELIMINATOR | +---------+---------+---------+---------+---------+---------+---------+--------+ | |Fire GRN |RotR GRN |RotR BLU | <---- ELIM 4P | +---------+---------+---------+---------+---------+---------+---------+--------+ | | | Left | Right | | <---- ASTRO BLASTER | +---------+---------+---------+---------+---------+---------+---------+--------+ | | Up | Left | Right | | <---- 005 | +---------+---------+---------+---------+---------+---------+---------+--------+ | | Up | Left | Right | | <---- MONSTER BASH | +---------+---------+---------+---------+---------+---------+---------+--------+ | | | Fire2 | | | <---- SPACE ODYSSEY | +---------+---------+---------+---------+---------+---------+---------+--------+ 0xF9 (371) NOTE: The port bits are active LOW +---------+---------+---------+---------+---------+---------+---------+--------+ | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | +=========+=========+=========+=========+=========+=========+=========+========+ | ----- | P1-13 | P1-15 | P1-19 | SW1-7 | SW1-3 | SW2-7 | SW2-3 | +---------+---------+---------+---------+---------+---------+---------+--------+ SPACE FURY ---> | 1Player | 2Player | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ ELIM 4P ---> |ThrustGRN|ThrustBLU| | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ ASTRO BLASTER ---> | 1Player | 2Player | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ 005 ---> | 1Player | 2Player | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ MONSTER BASH ---> | 1Player | 2Player | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ SPACE ODYSSEY ---> | 1Player | 2Player | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ 0xF8 (370) NOTE: The port bits are active LOW +---------+---------+---------+---------+---------+---------+---------+--------+ | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | +=========+=========+=========+=========+=========+=========+=========+========+ | COIN A | COIN B | SERVICE | P1-18 | SW1-8 | SW1-4 | SW2-8 | SW2-4 | +---------+---------+---------+---------+---------+---------+---------+--------+ ELIM 4P ---> |FIRE BLU | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ SPACE ODYSSEY ---> | Up | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ SWITCH MAPPINGS --------------- +------+------+------+------+------+------+------+------+ |SW1-8 |SW1-7 |SW1-6 |SW1-5 |SW1-4 |SW1-3 |SW1-2 |SW1-1 | +------+------+------+------+------+------+------+------+ F8:08 |F9:08 |FA:08 |FB:08 |F8:04 |F9:04 FA:04 FB:04 Zektor & | | | | | | Space Fury | | | | | | 1 -|------|------|------|------|------|--------------- upright 0 -|------|------|------|------|------|--------------- cocktail | | | | | | | 1 -|------|------|------|------|--------------- voice | 0 -|------|------|------|------|--------------- no voice | | | | | | 1 | 1 -|------|------|--------------- 5 ships | 0 | 1 -|------|------|--------------- 4 ships | 1 | 0 -|------|------|--------------- 3 ships | 0 | 0 -|------|------|--------------- 2 ships | | | | 1 | 1 -|--------------- hardest | 0 | 1 -|--------------- hard 1 = Open | 1 | 0 -|--------------- medium 0 = Closed | 0 | 0 -|--------------- easy +------+------+------+------+------+------+------+------+ |SW2-8 |SW2-7 |SW2-6 |SW2-5 |SW2-4 |SW2-3 |SW2-2 |SW2-1 | +------+------+------+------+------+------+------+------+ |F8:02 |F9:02 |FA:02 |FB:02 |F8:01 |F9:01 |FA:01 |FB:01 | | | | | | | | | | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 4 coin/ 1 play +------+------+------+------+------+------+------+------+ | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 3 coin/ 1 play +------+------+------+------+------+------+------+------+ | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 2 coin/ 1 play +------+------+------+------+------+------+------+------+ | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | 1 coin/ 1 play +------+------+------+------+------+------+------+------+ | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 1 coin/ 2 play +------+------+------+------+------+------+------+------+ | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 1 coin/ 3 play +------+------+------+------+------+------+------+------+ | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 coin/ 4 play +------+------+------+------+------+------+------+------+ | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 coin/ 5 play +------+------+------+------+------+------+------+------+ X/Y CONTROL BOARD ----------------- 0xBF (277) ????? set to 0 or (mostly to..) 4 0xBE (276) 16 bit product returned as L, H in two I/O operations 0xBD (275) current vector PC 8-11 (???) 0xBC (274) current vector PC 0-7 (???) VIDEO BOARD (Raster) ----------- 0xBF (277) D0: 1 for cocktail flip, 0 to disable D1: 1 to initiate color RAM write, 0 to disable D2: always set to 1? BACKGROUND BOARD (Raster - Monster Bash) ---------------- NOTE: Used in conjunction with VIDEO BOARD. 0xBC (274) NOTE: D0-D1 should always equal D2-D3. D0-D1: Character bank for Background Video ROM (bit 1) (U13) D2-D3: Character bank for Background Video ROM (bit 2) (U8) D4-D6: Scene bank for Background Video ROM (U22) D7: 1 to draw background, 0 to clear 0xBF (277) D2: always set to 1? D6: 1 to initial background color RAM write, 0 to disable UNIVERSAL SOUND BOARD --------------------- 0x3f (077) ------------------------------- I/O OUTPUT PORTS ------------------------------- CPU BOARD --------- 0xF9 (371) +---------+---------+---------+---------+---------+---------+---------+--------+ | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | +=========+=========+=========+=========+=========+=========+=========+========+ |CoinCtrA |CoinCtrB | | | | | | | +---------+---------+---------+---------+---------+---------+---------+--------+ 0xF8 (370) +---------+---------+---------+---------+---------+---------+---------+--------+ | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | +=========+=========+=========+=========+=========+=========+=========+========+ | | | | | | | |Port Sel| +---------+---------+---------+---------+---------+---------+---------+--------+ 4player Eliminator +---------+---------+---------+---------+---------+---------+---------+--------+ | select coin switches | 1 | 1 | 1 | 1 | 0 | +---------+---------+---------+---------+---------+---------+---------+--------+ | select red/yel inputs | 1 | 1 | 1 | 1 | 1 | +---------+---------+---------+---------+---------+---------+---------+--------+ | | 0 | 1 | 1 | coin cntrs 0-3 | +---------+---------+---------+---------+---------+---------+---------+--------+ X/Y Control ----------- 0xbf (277) 0xbe (276) 8 bit multiplier 0xbd (275) 8 bit multiplicand Universal Sound Board (800-0377) -------------------------------- 0x3f (077) 1000 0000 = reset 8035 (OUTPUT) ccc cccc = sound command 0x3f 1000 000x == board ready for next byte from main CPU The universal sound board has a 4k RAM for program code which is downloaded from the main processor. The CPU on the sound card is reset by toggling the msb on port 3f. The board is ready for the next sound command when a read of port 3f returns 80 (the ls bit is masked off). Here are the commands sent to the board during self test in tac/scan The coin inserted sound appears to be 0x2c There appear to be continuous sounds that you have to turn off with a second command, and one-shot sounds. There is a four byte sequence that is sent out before the first sound was sent. Each byte sent to the USB waits for 0x80 to be returned on port 3f. Initial byte sequence for tac/scan 0c 04 37 38 TAC/SCAN Sounds (USB loaded from A000 in main EPROMS) 40 (PLAYER SHIP ROAR) 10 (stop) 18 (PLAYER SHIP LASER) 20 (PLAYER SHIP EXPLOSION) 28 (PLAYER SHIP DOCKING) 48 (TUNNEL HIGH LIGHT) 50 (STINGER THRUST) 52 (stop) 51 (STINGER LASER) 52 (stop) 54 (STINGER EXPLOSION) 62 (ENEMY BULLET) 6e (ENEMY SHIP EXPLOSION) Star Trk Sounds (USB Loaded from 5400 in main EPROMs) 8 PHASER a PHOTON e TARGETING 10 DENY 12 SHEILD HIT 14 ENTERPRISE HIT 16 ENT EXPLOSION 1a KLINGON EXPLOSION 1c DOCK 1e STARBASE HIT 11 STARBASE RED 22 STARBASE EXPLOSION 24 SMALL BONUS 25 LARGE BONUS 26 STARBASE INTRO 27 KLINGON INTRO 28 ENTERPRISE INTRO 29 PLAYER CHANGE 2e KLINGON FIRE 4,5 IMPULSE 6,7 WARP c,d RED ALERT 18,2f WARP SUCK 19,2f SAUCER EXIT 2c,21 NOMAD MOTION 2d,21 NOMAD STOPPED 2b COIN DROP MUSIC 2a HIGH SCORE MUSIC Zektor Sound Board (800-3249) ----------------------------- Ref Des ELIMINATOR ZEKTOR R5 10K 4.7K R9 33K 12K R71 270K 100K R79 2 MEG unused R122 220K 390K R132 220K 100K C9 0.01uF 0.0047uF C46 0.022uF 0.047uF Eliminator Sound Board (800-3174) --------------------------------- inputs 0x3c-0x3f d0 speech ready outputs ( 0 = ON) 0x3e (076) d7 torpedo 2 d6 torpedo 1 d5 bounce d4 explosion 3 d3 explosion 2 d2 explosion 1 d1 fireball d0 - 0x3f (077) d7 background msb d6 background lsb d5 enemy ship d4 skitter d3 thrust msb d2 thrust lsb d1 thrust hi d0 thrust lo Space Fury Sound Board (800-0241) --------------------------------- 0x3e (076) (0 = ON) d7 partial warship, low frequency oscillation d6 star spin d5 - d4 - d3 - d2 thrust, low frequency noise d1 fire, metalic buzz d0 craft scale, rising tone 0x3f (077) d7 - d6 - d5 docking bang d4 large explosion d3 small explosion, low frequency noise d2 fireball d1 shot d0 crafts joining Speech Board Description ======================== The speech board is similar in architecture to the universal sound board. It has an 8035 (or 8039) microcontroller which communicates with the main Z80 through port 0x38. The board uses a General Instruments SP0250 Speech Synthesiser which encodes in a proprietary LPC-12 format. This is all i've been able to find out about the SP0250 There are 15 parameters each of 1 byte, which are input to pins 3 2 28 27 26 25 24 23 (3 is Most Significant Bit). The bytes are labelled (in order) C21, C11, Amplitude, C22, C12, Pitch, C23, C13, Repeat, C24, C14, C25, C15, C26, C16. The C's are the twelve (reflection?) coefficients, where the MSB is the sign, 1 = pos. The amplitude in direct data mode has the 3 MSBs as exponent. The pitch does not have a sign bit. Repeat has MSB set to 0, MSB-1 set to V(u), remaining bits the repeat value. It does not say what V(u) is (there is a bar over the u). It may be the voiced/unvoiced flag. Finally there is a description of a byte which may be an alternative to the amplitude. The MSB is sign 1 = neg, the rest is amplitude. A note says "exponent from normal mode remains until changed". Space Fury Speech Board (800-0183) --------------------------------- inputs 0x39 (071) D7 = Votrax done outputs 0x38 (070) D0-D6 = 8035 inputs , D7 = T0 Toggle Output phrase number, wait, or with 0x80 and output again. 0x39 (071) Votrax P0-P5 0x3A (072) Votrax ctl 0x3B (073) Timer 0,1,2, mono,L,R sel 0x3C (074) to 0x3F (077) 8253 Timer Note: The Votrax and Timer chip, along with the left/right mux are left unpopulated on the 800-0294 version used in Zektor and Star Trek. There appears to be a 'stereo spreader' circuit on the board, using a bucket-brigade analog delay. Looking at the fuse map for the address decoder prom, there appears to be no way to address the analog switch on the output of the SP250 so it always stays in the 'A' switch position. Voice Board Phrases (Space Fury) -------------------------------- 0x38 (070) 0 = no phrase 1 = "SO" 2 = "A CREATURE FOR MY AMUSEMENT" 3 = "PREPARE FOR BATTLE" 4 = "YOU DEFEATED MY SCOUTS" 5 = "WELL MY CRUISERS WILL DESTROY YOU" 6 = "YOU ARE STARTING TO ANNOY ME CREATURE" 7 = "MY DESTROYERS WILL ANNIHILATE YOU" 8 = "YOU SURVIVED!" 9 = "WARSHIPS, DISPOSE OF THIS ANNOYANCE AT ONCE" A = "WELL DONE" B = "PREPARE TO BATTLE MY ENTIRE FLEET" C = "IS THERE NO WARRIOR MIGHTER THAN I?" D = "DOES ANYONE DARE CHALLENGE MY IMPERIAL FLEET?" E = "OUR BATTLE IS COMPLETED WARRIOR" F = "YOU WERE" 10 = "AN EASY" 11 = "AN AMUSING" 12 = "AN ADEQUATE" 13 = "A STIMULATING" 14 = "AN OUTSTANDING" 15 = "OPPONENT" 16 = no phrase 3f = concatinate phrases Voice Board Phrases (Star Trek) ------------------------------- 0x38 (070) 00 = no phrase 01 = "COMMAND THE ENTERPRISE" 02 = "PLAY STAR TREK" 03 = "WELCOME ABOARD, CAPTAIN" (SPOCK) 04 = "CONGRATULATIONS" 05 = "HIGH SCORE" 06 = "PRESS PLAYER ONE" 07 = "OR PLAYER TWO" 08 = "START" 09 = "BE THE CAPTAIN OF THE STARSHIP ENTERPRISE" (SCOTTY) 0A = "DAMAGE REPAIRED, SIR" (SCOTTY) 0B = "SECTOR SECURED" (CHECKOV) 0C = "ENTERING SECTOR" (SPOCK) 0D = "ZERO" 0E = "ONE" 0F = "TWO" 10 = "THREE" 11 = "FOUR" 12 = "FIVE" 13 = "SIX" 14 = "SEVEN" 15 = "EIGHT" 16 = "NINE" 17 = "POINT" 18 = "POINT" (HIGHER PITCH) 19 = "RED ALERT" Voice Board Phrases (Zektor) ---------------------------- 0x38 (070) 0 = no phrase 1 = "So, you've come to take Ascella back" (Male) 2 = "I rule Faltar now" (M) 3 = "You'll have to fight for it" (M) 4 = "Centaurus is my world now" (M) 5 = "Sooo... We meet again creature" (M) 6 = "Prepare for battle" (M) 7 = "Warriors needed to defeat alien robots" (Female) 8 = "Approaching" (F) 9 = "defense ring" (F) A = "the city" (F) B = "One" (F) C = "Two" (F) D = "Three" (F) E = "Ahhh... Another warrior attempting to regain Baitos" F = "You will not take it from me" (F) 10 = "I have conquered Eridonus" (F) 11 = "Once Deneballa was yours" (F) 12 = "Graffas belongs to me" (F) 13 = "I will never give it back" (F) 14 = no phrase Display Controller ----------------- The vector processor starts at vector ram adr 0 The vector PC is reset 40 times /second. Display list state machine stops when Last Symbol detected. Vector Display RAM contents: Symbol Instructions (10 bytes / symbol) byte 1 <draw symbol, last symbol> L x x x x x x D ^ ^ | | | +-visible | +- last symbol byte 2,3 X start (DAC initial) x axis up/down counters byte 4,5 Y start (DAC initial) y axis up/down counters byte 6,7 adr of line instructions vector address counter byte 8,9 appearance, angle symbol angle latch 10 bit angle byte 10 size draw time multiplier 0xff == 2x 0x80 == 1x 0x40 == 1/2 Line Instructions ( 4 bytes / line ) byte 1 <last line, color, unblank> L R R G G B B D ^ ^ | +-visible +-last vector byte 2 length vector length byte 3 line angle vector angle byte 4 screen quadrant (0-3) direction to draw 2 | 3 --+-- 1 | 0 Bytes 3 and 4 really could be thought of as a little-endian 10 bit angle, but the hardware is described this way in the service manual. In hardware, the top two bits determine count direction in the x or y up/down counters that draw the line. The vector length is the value loaded into the x and y counters after scaling and being scaled by a hardware lookup in a sine / cosine lookup ROM. A line with length x and angle 0 has all of its length component in the x count value, a line with length x and (binary) angle 45 degrees has equal length values in x and y. Screen Coordinate System: The screen position is represented by a pair of 11 bit values (two bytes each) in each symbol structure. The screen itself can be thought of as this: 2048 | | | | | +------------ 2048 0,0 That is, the origin is in the lower left hand corner and coordinates move up and right. The center of the screen is 0x400,0x400. A hardware clipping circuit clips the screen to a subset of this amount: 1536 +-------------------+ | | | | | | 512| 1024,1024 |1536 | | | | | | +-------------------+ 512 The center is at 1024,1024. The display "clips" at the same values on the x and y axis, so since the display isn't exactly square there must be a little distortion. (a square should be slightly wider than tall on the screen) Hardware Scaling: Scaling is simple binary scaling with a single byte value. 0x80 appears to be 1:1, 0xFF is 2:1 0x40 is 1:2, 0x20 is 1:4, 0x10 is 1:8 etc... This means that there's more "dynamic range" in the bottom end of the scaling, so things should look nicer if drawn large and scaled down. Since the vector generator always starts at 0 in vector RAM, and there is no way to stop the vector PC from resetting every 40th of a second, the symbol list for a game is not very dynamic. There is hardware on the display controller card to be able to read the current positon of the display PC, but no games appear to use it. Items to be displayed are marked as visible when they should appear on the screen, and the end of the symbol list is marked with the most significant bit of the first symbol byte set to '1'. Symbol Samples: "0" 51 40 00 01 draw top left to right 51 60 30 02 draw right side (slanted) top to bottom 51 40 00 03 draw bottom right to left d1 60 30 00 draw left side (slanted) bottom to top "1" 7E 20 00 01 move 0x20 units to the right d1 60 30 02 draw (slanted) top to bottom "2" 51 40 00 01 draw top left to right 51 30 30 02 symbol drawn "downwards".... 51 40 00 03 51 30 30 02 d1 40 00 01 "3" 51 40 00 01 top bar 51 60 30 02 right side 51 40 00 03 bottom 7e 5d a6 00 move to middle of right side d1 30 00 03 draw middle bar right to left "4" 51 30 30 02 51 48 00 01 7e 2e 00 00 d1 60 30 02 "5" 51 40 00 01 7e 40 00 03 51 30 30 02 51 40 00 01 51 30 30 02 d1 40 00 03 Raster Display Controller ------------------------- All graphics are in 2-bit color. There are 256 different possible color values, which are determined by a byte containing the bits BBGGGRRR. Four of these bytes are used to describe the colors for any given sprite value. The color values are stored in a RAM that holds 64 bytes of information. These values are periodically changed during game play. Sprites are represented by a byte; every 16 consecutive sprites share the same color scheme. Hence the 64 bytes (16 sprite color sets * 4 colors). The Monster Bash Background Board has an additional 64-byte RAM to hold the background colors. The graphics data is stored as 1-bit data - the two color bits are kept completely separate. On the Video Board, U16-U23 holds one color bit, and U24-U31 holds the other color bit. On the Monster Bash Background Board, U8 holds one color bit, and U13 holds the other color bit. The sprites are 8 pixels by 8 pixels. Each sprite is stored as 8 consecutive bytes in memory. The screen size is 28 sprites in the X direction by 32 sprites in the Y direction. The Infamous U21 Security Chip ------------------------------ There are a total of six different security chips produced - 31562, 31563, 31564, 31570, 31576, and 31582. They all work the same conceptually, but have slightly different implementations. In general, this chip interrupts the Z80 memory write instruction LD ($XXYY),A (opcode $32) and changes the value of YY before writing to memory. There are four different algorithms for changing YY. These algorithms seem like they could be implemented by simply reordering the bits in YY and possibly inverting one of them. The four algorithms can be implemented in C using the following code. Note that one algorithm doesn't do anything - the output matches the input. 'x' represents the output, 'i' represents the input. Algorithm A: /* A */ x=i; Algorithm B: /* B */ x=i & 0x03; x+=((i & 0x80) >> 1); x+=((i & 0x60) >> 3); x+=((~i) & 0x10); x+=((i & 0x08) << 2); x+=((i & 0x04) << 5); x &= 0xFF; Algorithm C: /* C */ x=i & 0x03; x+=((i & 0x80) >> 4); x+=(((~i) & 0x40) >> 1); x+=((i & 0x20) >> 1); x+=((i & 0x10) >> 2); x+=((i & 0x08) << 3); x+=((i & 0x04) << 5); x &= 0xFF; Algorithm D: /* D */ x=i & 0x23; x+=((i & 0xC0) >> 4); x+=((i & 0x10) << 2); x+=((i & 0x08) << 1); x+=(((~i) & 0x04) << 5); x &= 0xFF; The algorithm to use for any particular $32 instruction is determined by two bits of the address of the $32 instruction. The two bits used, and which algorithms they map to, are the only differences between the different security chips. Here are the different mappings: 31562: address bits xxxxxxXX XX=00: Algorithm D XX=01: Algorithm C XX=10: Algorithm B XX=11: Algorithm A 31563: address bits xxxxXxxX XX=00: Algorithm D XX=01: Algorithm C XX=10: Algorithm B XX=11: Algorithm A 31564: address bits xxxxxxXX XX=00: Algorithm A XX=01: Algorithm B XX=10: Algorithm C XX=11: Algorithm D 31570: address bits xxxxXxxX XX=00: Algorithm B XX=01: Algorithm A XX=10: Algorithm D XX=11: Algorithm C 31576: address bits xxxxXxxX XX=00: Algorithm A XX=01: Algorithm B XX=10: Algorithm C XX=11: Algorithm D 31582: address bits xxxXxxxX XX=00: Algorithm A XX=01: Algorithm B XX=10: Algorithm C XX=11: Algorithm D After reading all this, some examples would probably be helpful. :) Example 1: The hardware contains the 31582 chip. Disassembling the ROM code, you discover the following line: 204F:32 20 C8 LD ($C820), A The $32 occurs at $204F = 00100000 01001111. We compare against which bits are necessary: 01001111 xxxXxxxX Our pattern is 01, which is Algorithm B. After putting $20 through Algorithm B, we end up with $14. The post-security chip line becomes 204F:32 14 C8 LD ($C814), A Example 2: The hardware contains the 31564 chip. Disassembling the ROM code, you discover the following line: 6463:32 78 E0 LD ($E078), A The $32 occurs at $6463 = 01100100 01100011. We compare against which bits are necessary: 01100011 xxxxxxXX Our pattern is 11, which is Algorithm D. After putting $78 through Algorithm D, we end up with $F4. The post-security chip line becomes 6463:32 F4 E0 LD ($E0F4), A Sega G80 Backplane Pinout ------------------------- 1 ground A ground 2 a15 B a7 3 a14 C a6 4 a13 D a5 5 a12 E a4 6 a11 F a3 7 a10 H a2 8 a9 J a1 9 a8 K a0 10 d7 L d3 11 d6 M d2 12 d5 N d1 13 d4 P d0 14 /wait (used by Hw multiplier) R /reset 15 /int S /edgint (40Hz interrupt) 16 /nmi T /extclk (CPU clock in) 17 /ext clk sel (tied low) U clk out 18 /memr V /memw 19 /input W /output 20 /rfsh X /mreq 21 /intack Y /AC (ac power detect) 22 +5 Z +5 23 +5 a +5 24 -5 b -5 25 +12 c +12 26 -12 d -12 27 e 28 /hlt CPU halted f M1 29 clk phase 2 h 30 /panel reset j 31 src k 32 /add l 33 m /fetch 34 n /pcc 35 p 36 r 7.5Mhz 37 s 38 t 39 u 40 v 41 w /pcr (vector pc reset) 42 x speech rdy 43 ground y ground ROM Address Map --------------- Eliminator Elim4Player Space Fury Zektor TAC/SCAN Star Trk -----+-----------+-----------+-----------+-------+---------+---------+ 0000 | 969 | 1390 | 969 | 1611 | 1711 | 1873 | CPU u25 -----+-----------+-----------+-----------+-------+---------+---------+ 0800 | 1333 | 1347 | 960 | 1586 | 1670 | 1848 | ROM u1 -----+-----------+-----------+-----------+-------+---------+---------+ 1000 | 1334 | 1348 | 961 | 1587 | 1671 | 1849 | ROM u2 -----+-----------+-----------+-----------+-------+---------+---------+ 1800 | 1335 | 1349 | 962 | 1588 | 1672 | 1850 | ROM u3 -----+-----------+-----------+-----------+-------+---------+---------+ 2000 | 1336 | 1350 | 963 | 1589 | 1673 | 1851 | ROM u4 -----+-----------+-----------+-----------+-------+---------+---------+ 2800 | 1337 | 1351 | 964 | 1590 | 1674 | 1852 | ROM u5 -----+-----------+-----------+-----------+-------+---------+---------+ 3000 | 1338 | 1352 | 965 | 1591 | 1675 | 1853 | ROM u6 -----+-----------+-----------+-----------+-------+---------+---------+ 3800 | 1339 | 1353 | 966 | 1592 | 1676 | 1854 | ROM u7 -----+-----------+-----------+-----------+-------+---------+---------+ 4000 | 1340 | 1354 | 967 | 1593 | 1677 | 1855 | ROM u8 -----+-----------+-----------+-----------+-------+---------+---------+ 4800 | 1341 | 1355 | 968 | 1594 | 1678 | 1856 | ROM u9 -----+-----------+-----------+-----------+-------+---------+---------+ 5000 | 1342 | 1356 | | 1595 | 1679 | 1857 | ROM u10 -----+-----------+-----------+-----------+-------+---------+---------+ 5800 | 1343 | 1357 | | 1596 | 1680 | 1858 | ROM u11 -----+-----------+-----------+-----------+-------+---------+---------+ 6000 | 1344 | 1358 | | 1597 | 1681 | 1859 | ROM u12 -----+-----------+-----------+-----------+-------+---------+---------+ 6800 | 1345 | 1359 | | 1598 | 1682 | 1860 | ROM u13 -----+-----------+-----------+-----------+-------+---------+---------+ 7000 | | 1360 | | 1599 | 1683 | 1861 | ROM u14 -----+-----------+-----------+-----------+-------+---------+---------+ 7800 | | 1600 | 1684 | 1862 | ROM u15 -----+-----------+-----------+-----------+-------+---------+---------+ 8000 | | 1601 | 1685 | 1863 | ROM u16 -----+-----------+-----------+-----------+-------+---------+---------+ 8800 | | 1602 | 1686 | 1864 | ROM u17 -----+-----------+-----------+-----------+-------+---------+---------+ 9000 | | 1603 | 1687 | 1865 | ROM u18 -----+-----------+-----------+-----------+-------+---------+---------+ 9800 | | 1604 | 1688 | 1866 | ROM u19 -----+-----------+-----------+-----------+-------+---------+---------+ A000 | | 1605 | 1709 | 1867 | ROM u20 -----+-----------+-----------+-----------+-------+---------+---------+ A800 | | 1606 | 1710 | 1868 | ROM u21 -----+-----------+-----------+-----------+-------+---------+---------+ B000 | | 1869 | ROM u22 -----+-----------+-----------+-----------+-------+---------+---------+ B800 | | 1870 | ROM u23 -----+-----------+-----------+-----------+-------+---------+---------+ Change Log ---------- 25 Oct 1997 Add raster games info, security chip info, made Y2K compliant 1 Aug 1997 Fill in trek speech info 24 Jun 1997 Add info on 4 player Eliminator 12 Jun 1997 Add Trek sound descriptions 8 Jun 1997 Add basic info for USB, ROM adr map 6 Jun 1997 Correct rotl/r bits for Space Fury, add 1 player control bits for Eliminator. 30 May 1997 Add G80 backplane pinout 29 May 1997 Redo input port info, add protocol for speech board and add Player1/2 switch info for Space Fury. 3 May 1997 Add phrases from Zektor, correct port 0xfc info 1 May 1997 Add sound register defns for Eliminator 3 Apr 1997 Add version number, and a bunch of new info on switches and sound. 4 Apr 1997 Add some sample vector data 22 Apr 1997 Add screen coordinate and scaling info