Difference between revisions of "Control Pad (Mega Drive)"

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The '''Sega Mega Drive Control Pad''' is the official controller of the [[Sega Mega Drive]] (or Sega Genesis in North America). There are two main types of official Mega Drive control pad - "three button" and "six button" varieties, with the latter being brought in to replace the former towards the end of the system's lifespan (1994/1995). There are of course many other options as far as controllers go, including the [[Arcade Power Stick]] - a decendant of previous Sega joysticks. This article covers only the two basic pads.
+
{{AccessoryBob
 +
| accessoryimage=Pad MD JP I.jpg
 +
| imgwidth=260
 +
| title=Control Pad
 +
| maker=[[Sega]]
 +
| madefor=[[Sega Mega Drive]]
 +
| releases={{releasesMD
 +
| md_date_jp=1988
 +
| md_code_jp=SJ-3500
 +
| md_rrp_jp=2,000{{ref|http://sega.jp/fb/segahard/md/pad.html}}
 +
| md_date_eu=1990
 +
| md_code_eu=
 +
| md_rrp_uk=14.99{{fileref|SegaForce UK 02.pdf|page=65}}
 +
| md_date_us=1989
 +
| md_code_us=MK-1650
 +
| md_date_ca=1989
 +
| md_code_ca=1650-22
 +
}}
 +
}}
 +
The '''Sega Mega Drive Control Pad''' (コントロールパッド) is the official controller of the [[Sega Mega Drive]] (or Sega Genesis in North America). Three button controllers are known officially as '''Control Pads''' in both North America and Europe, and '''SJ-3500s''' in Japan (following a system set up by the [[SG-1000]]). There are many "updates" and alternatives to this controller, the most notable being the [[Six Button Control Pad (Mega Drive)|Six Button Control Pad]]. This article covers only the basic three button variants.  
  
Three button controllers are known officially as '''Control Pads''' in both North America and Europe, and '''SJ-3500s''' in Japan (following a system set up by the [[SG-1000]]). Six button controllers are known as '''SJ-6000s''' in Japan, '''6 Button Arcade Pads''' in North America and '''Six Button Control Pads''' in Europe.
+
Mega Drive control pads are the logical progression from [[Control Pad (Master System)|Master System control pads]], replacing {{1}} and {{2}} with {{A}} and {{B}} respectively, while adding an extra two face buttons, {{C}} and {{Start}} to bring the total number of buttons to four. Also featured is a circular D-Pad, designed to allow for movements in eight directions. Unlike [[Nintendo]]'s systems, the buttons (or "triggers" as they were initially called) are arranged in alphabetical order from left to right, a practise which would continue not only with future Sega consoles, but would inspire the controllers of the Neo Geo, 3DO and [[Xbox]] lines.
 
 
Mega Drive control pads are the logical progression from [[Control Pad (Master System)|Master System control pads]]. Copying a system set up by [[Nintendo]], the three button Mega Drive control pad adds, as the name suggests, an extra face button (or "Trigger" as it was initially called), {{C}}, to go with {{A}}, {{B}} and {{Start}}. {{A}} and {{B}} map to {{1}} and {{2}} on a Master System controller, while {{Start}} eliminates the need for a pause button placed on the console unit itself. Six button pads add {{X}}, {{Y}}, {{Z}} and "MODE", meaning the total number of buttons is equal to that of the Super Nintendo.
 
 
 
The six button control pad would be used as a basis for the [[Control Pad (Saturn)|Sega Saturn Control Pad]], though the MODE button would be scrapped in favour of an extra two shoulder buttons, {{L}} and {{R}}.
 
  
 
Mega Drive controllers are notable for being one of the first control pads to be ergonomically designed for the user's hands. Though improvements were made in the coming years, previous systems had cornered edges with their controllers, meaning they were often uncomfortable to hold after several hours of play. The Mega Drive controller is rounded, and has its buttons placed in easier to reach positions.
 
Mega Drive controllers are notable for being one of the first control pads to be ergonomically designed for the user's hands. Though improvements were made in the coming years, previous systems had cornered edges with their controllers, meaning they were often uncomfortable to hold after several hours of play. The Mega Drive controller is rounded, and has its buttons placed in easier to reach positions.
  
 
==Variations==
 
==Variations==
Control pads remained mostly the same across regions, but the colouring can determine the region and revision of the accessory.
+
Control pads remained mostly the same across regions, but the colouring can determine the region and revision of the accessory. A minor addition added in the early 1990s is a little plastic lump on the {{B}} button, presumably to help users recognise where their right hand thumb was.
 
 
===Japan===
 
====SJ-3500====
 
The first controller for the Sega Mega Drive, released in 1988. The {{A}}, {{B}} and {{C}} buttons are printed in red lettering and the {{start}} button is blue. The text at the top of the controller reads "Computer Video Game Control Pad".
 
<gallery>
 
Image:Pad MD JP I.jpg|Control Pad
 
File:MDController SJ3500 JP Box Front.jpg|Front of box
 
File:MDController SJ3500 JP Box Back.jpg|Back of box
 
</gallery>
 
 
 
====SJ-6000 / Sega Club 6 button Jr====
 
The Japanese 6-button controller. Again, the {{Start}} button is blue, but the text is not coloured. It is, however, rendered in a serif font, as opposed to a sans-serif font used in international models. This would also be used in the [[Sega Saturn]].
 
 
 
The Japanese model is smaller than its international counterparts. It is not the first controller to be made purposely smaller for a Japanese audience as the [[Sega Master System]]'s [[Sports Pad]] also varies in size.
 
<gallery>
 
Image:Pad MD JP II.jpg|Control Pad
 
File:MDController SJ6000 JP Box Front.jpg|Front of box
 
</gallery>
 
 
 
===North America===
 
====Sega Genesis Control Pad (Model No. 1650)====
 
Initial Sega Genesis three-button controllers had a white {{Start}} button, with red coloured text. The arrows surrounding the D-Pad are also coloured red, and the printed text in the middle reads "Sega Genesis". These controllers match the Model 1 Genesis, and were distributed with the console during its early years.
 
<gallery>
 
Image:Pad_gen_v1.jpg|Control Pad
 
</gallery>
 
 
 
====Sega Genesis Control Pad (v2) (Model No. 1650)====
 
When the Sega Genesis II rolled out, so were these updated controllers. The arrows were changed to white and the text was left black, much like the Genesis II console. The text "TRIGGER" was moved below the three buttons, and extra labels for {{A}}, {{B}} and {{C}} were added on top.
 
 
 
But it's not just the outside appearance which is different here. These models have an improved D-Pad mechanism, employing a metal ball-bearing for the pad to rock on.  This prevented the wear which plagued the original design, which used a plastic nub for the rocking motion and would eventually wear down with frequent use. A minor addition is a little plastic lump on the {{B}} button, presumably to help users recognise where their right hand thumb was.
 
<gallery>
 
File:Pad MD Gen.jpg|Control Pad
 
</gallery>
 
 
 
====Sega Genesis Control Pad (v3) (Model No. 1650)====
 
Though this controller appears to be identical to the above, it once again has an updated D-Pad.  This was the first iteration of Sega's 2-Piece D-Pad mechanism, used in every official subsequent controller up to and including the Sega Saturn's.  Rather than providing the rocking motion by a plastic nub or ball-bearing, there is a molded dome underneath the outside half of the D-Pad which allows the D-Pad to glide smoothly in a circle.  This design was also plagued with wear like the first model, eventually resulting in all four directions being able to be pressed simultaneously.
 
<gallery>
 
Image:Pad_gen_v3.jpg|Control Pad
 
</gallery>
 
 
 
====Sega Genesis 6-Button Control Pad (MK-1653)====
 
This is the standard, regular size 6-button controller for the Genesis. Devoid of colour (bar a grey {{Start}} button), this controller debuted late into the Genesis' lifespan and uses the same D-Pad mechanism as the third three button control pad. It also bears the "SEGA" logo, rather than a Genesis one.
 
<gallery>
 
Image:Pad MD Gen3.jpg|Control Pad
 
</gallery>
 
 
 
====Sega Genesis 3 Control Pad (MK-1470)====
 
This was the controller which was included with the [[Genesis 3]] console.  As the Genesis 3 was an economy model, manufacturer [[Majesco]] sourced them from a third-party manufacturer, based heavily on the Japanese SJ-6000 model.  This became the most popular design and was simply rebranded with a different logo for each third-party company who decided to market it. It features six buttons, mode (black and moved to the front of the unit) and start (blue), and includes a switch to enable rapid-fire for all 6 buttons and slow motion via rapid pause.
 
<gallery>
 
Image:Pad_gen3.jpg|Control Pad
 
File:MDController MK-1470 US Box Front.jpg|Front of box
 
</gallery>
 
===Europe===
 
====Sega Mega Drive Control Pad====
 
Almost identical to the second Sega Genesis three-button gamepad, the first European Mega Drive controller sports a white {{Start}} button, the text "SEGA" and "Mega Drive Control Pad".
 
<gallery>
 
Image:Pad MD PAL I.jpg|Control Pad
 
File:MDController EU Box Front.jpg|Front of box
 
</gallery>
 
 
 
====Sega Mega Drive Control Pad II ====
 
The second model of Mega Drive control identical to the above varient, however now features a red {{Start}} button instead of a white one, to correspond to the revised Sega Mega Drive II. This would become the most common Mega Drive controller, as far more Model IIs were sold in Europe than Model Is.
 
<gallery>
 
File:Pad MD PAL II.jpg
 
 
 
</gallery>
 
====Sega Mega Drive Six Button Control Pad (MK-1653) ====
 
The European version of the 6-button control pad also contains a red start button, but is otherwise identical to the North American model.
 
<gallery>
 
File:MDController MK1653 EU Box Front.jpg|Front of box
 
</gallery>
 
  
==Brazil==
+
Early versions of this controller used the same internals as the original design, but later models have an improved D-Pad mechanism, employing a metal ball-bearing for the pad to rock on.  This prevents wear which plagues the original design, which uses a plastic nub for the rocking motion and will eventually wear down with frequent use. Later versions employ a D-Pad with a two-piece fulcrum design as seen on the Six Button Control Pad and all Sega Saturn pads.
  
==Asia==
+
<!-- rewrite
 +
This was the first iteration of Sega's two-piece D-pad mechanism, used in every official subsequent controller up to and including the Sega Saturn's.  Rather than providing the rocking motion by a plastic nub or ball-bearing, there is a molded dome underneath the outside half of the D-pad which allows the D-pad to glide smoothly in a circle.  This design was also plagued with wear like the first model, eventually resulting in all four directions being able to be pressed simultaneously. -->
  
==South Korea==
+
<gallery widths="200px">
===Super Aladdin Boy Control Pad===
+
File:Pad MD JP I.jpg|SJ-3500 (Japan; 1988)
The control pad that debuted along with Korea's Super Aladdin Boy is very similar to the first Japanese model. It contains a blue {{Start}} button, red button text and the text "COMPUTER VIDEO GAME CONTROL PAD" printed on top. This is all rounded off with a Samsung logo in the middle.
+
File:MD JP Control Pad late model.jpg|SJ-3500 (Japan; 1991)
<gallery>
+
File:Pad_gen_v1.jpg|MK-1650 (US; 1989)
File:MDControlPad SK 1.jpg
+
File:Pad MD Gen.jpg|MK-1650 (US; 1991)
 +
File:Pad_gen_v3.jpg|MK-1650 (US; 1991)
 +
File:MDControlPad EU 3BV2.jpg|(Europe; 1990)
 +
File:Pad MD PAL I.jpg|(Europe; 1991)
 +
File:Pad MD PAL II.jpg|(Europe; 1993)
 +
File:MDControlPad SK 1.jpg|(South Korea; 1990)
 
</gallery>
 
</gallery>
  
 
==Technical Information==
 
==Technical Information==
===3-button Control Pads===
 
 
The chip inside the control pad is a 74HC157. This is a high-speed CMOS quad 2-line to 1-line multiplexer.  Basically, how this works is there are two inputs ( A and B ) for every output ( Y ).  There are four groups like this.  There is one select signal for the whole chip. When the select signal is low, the output ( Y ) is the same as input A.  When the select signal is high, the output Y is the same as input B.  The pinout for the chip is as follows:
 
The chip inside the control pad is a 74HC157. This is a high-speed CMOS quad 2-line to 1-line multiplexer.  Basically, how this works is there are two inputs ( A and B ) for every output ( Y ).  There are four groups like this.  There is one select signal for the whole chip. When the select signal is low, the output ( Y ) is the same as input A.  When the select signal is high, the output Y is the same as input B.  The pinout for the chip is as follows:
  
Line 133: Line 82:
 
|}
 
|}
  
All the controls are done with switches.  Up is a switch, Down is a switch, etc. Now, I will be referring to the output of these switches later on.  The output is usually high when the switch isn't pressed. When the button is pushed, the output goes low.  This is accomplished by connecting the output to +5V through a 10k resistor.  The button is then attached between the output and ground.  It looks like this:
+
All the controls are done with switches.  Up is a switch, Down is a switch, etc. The output is usually high when the switch isn't pressed. When the button is pushed, the output goes low.  This is accomplished by connecting the output to +5V through a 10k resistor.  The button is then attached between the output and ground.  It looks like this:
 
   
 
   
 
     +5V -----/\/\/------+--------- Output
 
     +5V -----/\/\/------+--------- Output
Line 159: Line 108:
 
|Line 4||Pin 7 of the chip. Output 2Y.
 
|Line 4||Pin 7 of the chip. Output 2Y.
 
|-
 
|-
|Line 5||This line carries in +5V.  It is connected to the +5V bus line.
+
|Line 5||This line brings in +5V.  It is connected to the +5V bus line.
 
|-
 
|-
 
|Line 6 (TL)||Pin 9 of the chip. Output 3Y.
 
|Line 6 (TL)||Pin 9 of the chip. Output 3Y.
 
|-
 
|-
|Line 7 (TH)||Pin 1 of the chip. This carries in a select signal from the Genesis. This is a signal which varies rapidly and controls which input goes through the output
+
|Line 7 (TH)||Pin 1 of the chip. This carries in a select signal from the Genesis. This is a signal which varies rapidly and controls which input goes through the output.
 
|-
 
|-
 
|Line 8||Ground. This is connected to the Ground bus line.
 
|Line 8||Ground. This is connected to the Ground bus line.
Line 171: Line 120:
 
   
 
   
 
   
 
   
Now for the chips pin connections:
+
Now for the chip's pin connections:
 
   
 
   
 
{|class="prettytable"
 
{|class="prettytable"
Line 208: Line 157:
 
|}
 
|}
  
===6-button gamepads===
+
==Reading==
 +
Access to the controller ports is from bytes $A10003 (controller 1) and $A10005 (controller 2). TH must be set for output and the other pins for input, so bytes $A10009 and $A1000B must be set to $40 to read the respective controller.
  
In order to maintain backwards-compatibility with existing games, the 6-button gamepad acts the same as the 3-button if the controller inputs are read by the program a maximum of four times per frame. Reading the 3-button gamepad takes two cycles (once with TH=1 to read Up, Down, Left, Right, B, and C; and once with TH=0 to read A and Start), and the 6-button gamepad allows this to occur twice. It then reports the state of the extra buttons when the TH line is changed after the fourth cycle.
+
{| class="prettytable"
 
 
The full controller state is read in 8 cycles:
 
 
 
{|class="prettytable"
 
!Cycle||TH out||TR in||TL in||D3 in||D2 in||D1 in||D0 in
 
|-
 
|1||HI||C||B||Right||Left||Down||Up
 
|-
 
|2||LO||Start||A||0||0||Down||Up
 
|-
 
|3||HI||C||B||Right||Left||Down||Up
 
|-
 
|4||LO||Start||A||0||0||Down||Up
 
 
|-
 
|-
|5||HI||C||B||Right||Left||Down||Up
+
! Bit !! 7 !! 6 !! 5 !! 4 !! 3 !! 2 !! 1 !! 0
 
|-
 
|-
|6||LO||Start||A||0||0||0||0
+
! Pin !! - !! TH !! TL !! TR !! R !! L !! D || U
 
|-
 
|-
|7||HI||C||B||Mode||X||Y||Z
+
! TH = 0
 +
| ? || 0 || S || A || 0 || 0 || D || U
 
|-
 
|-
|8||LO||Start||A||---||---||---||---
+
! TH = 1
 +
| ? || 1 || C || B || R || L || D || U
 
|-
 
|-
 
|}
 
|}
  
Note: For the 8th cycle, '---' indicates "don't care". These values are all 1 on the 6-button controller, but may be mapped to other buttons on third-party controllers. Software expecting 6-button controllers should simply ignore these values. (6-button detection should be done on the 6th cycle, which presents four 0's on the D lines.)
+
Bit 7 latches the value written to it. It takes approximately the equivalent of two nop instructions for other types of controllers (such as the six-button controller) to respond to a TH change.
  
The controller's internal counter automatically resets after the eighth cycle. It also resets if it doesn't detect a rising-edge (0 to 1) transition on the TH line within 1.5 ms, which ensures that most games that don't support the extra buttons won't read them accidentally.
+
==External links==
 +
* [https://web.archive.org/web/*/http://sega.jp/fb/segahard/md/pad.html Sega of Japan catalogue page (Japanese)]
  
Some games incorrectly read the controller more than twice per frame, which may cause them to read the wrong set of buttons. If the Mode button is held in while starting the Genesis console, the 6-button gamepad will disable the extra buttons and act identically to a 3-button gamepad. (That is, the controller's internal counter will reset after the first two cycles instead of after eight cycles.)
+
==Physical scans==
 +
{{Scanbox
 +
| console=Mega Drive
 +
| region=JP (1988)
 +
| front=MDController SJ3500 JP Box Front.jpg
 +
| back=MDController SJ3500 JP Box Back.jpg
 +
| spinemissing=yes
 +
| square=yes
 +
}}{{Scanbox
 +
| console=Mega Drive
 +
| region=JP (1991)
 +
| front=MDController SJ3500 1991 JP Box Front.jpg
 +
| back=MDController SJ3500 1991 JP Box Back.jpg
 +
| spinemissing=yes
 +
| square=yes
 +
}}{{Scanbox
 +
| console=Mega Drive
 +
| region=US (1989)
 +
| front=MDControlPad US 3BV1 Box Front.jpg
 +
| back=MDControlPad US 3BV1 Box Back.jpg
 +
| spinemissing=yes
 +
| square=yes
 +
}}{{Scanbox
 +
| console=Mega Drive
 +
| region=US (1992)
 +
| front=ControlPad MD US Box Front 1992.jpg
 +
| back=ControlPad MD US Box Back 1992.jpg
 +
| spinemissing=yes
 +
| square=yes
 +
}}{{Scanbox
 +
| console=Mega Drive
 +
| region=US (1993)
 +
| front=ControlPad MD US Box Front 1993.jpg
 +
| back=
 +
| spinemissing=
 +
| square=yes
 +
}}{{Scanbox
 +
| console=Mega Drive
 +
| region=EU (1990)
 +
| front=MDControlPad EU 3BV2 Box Front.jpg
 +
| back=
 +
| spinemissing=
 +
| square=yes
 +
}}{{Scanbox
 +
| console=Mega Drive
 +
| region=EU (1993)
 +
| front=MDControlPadEU93 front.JPG
 +
| back=MDControlPadEU93 back.JPG
 +
| spinemissing=yes
 +
| square=yes
 +
}}{{Scanbox
 +
| console=Mega Drive
 +
| region=CA (1989)
 +
| front=ControlPad MD CA Box Front Old.jpg
 +
| back=
 +
| spinemissing=
 +
| square=yes
 +
}}{{Scanbox
 +
| console=Mega Drive
 +
| region=CA (1993)
 +
| front=ControlPad MD CA Box Front New.jpg
 +
| back=ControlPad MD CA Box Back New.jpg
 +
| spinemissing=yes
 +
| square=yes
 +
}}
  
 
{{MegaDrive}}
 
{{MegaDrive}}
  
[[Category:Mega Drive Accessories]]
+
[[Category:Control pads]]
[[Category:Control Pads]]
 

Revision as of 23:25, 17 May 2018

Pad MD JP I.jpg
Control Pad
Made for: Sega Mega Drive
Manufacturer: Sega
Release Date RRP Code
Sega Mega Drive
JP
¥2,0002,000[1] SJ-3500
Sega Mega Drive
US
MK-1650
Sega Mega Drive
EU
Sega Mega Drive
CA
1650-22

The Sega Mega Drive Control Pad (コントロールパッド) is the official controller of the Sega Mega Drive (or Sega Genesis in North America). Three button controllers are known officially as Control Pads in both North America and Europe, and SJ-3500s in Japan (following a system set up by the SG-1000). There are many "updates" and alternatives to this controller, the most notable being the Six Button Control Pad. This article covers only the basic three button variants.

Mega Drive control pads are the logical progression from Master System control pads, replacing 1 and 2 with A and B respectively, while adding an extra two face buttons, C and  START  to bring the total number of buttons to four. Also featured is a circular D-Pad, designed to allow for movements in eight directions. Unlike Nintendo's systems, the buttons (or "triggers" as they were initially called) are arranged in alphabetical order from left to right, a practise which would continue not only with future Sega consoles, but would inspire the controllers of the Neo Geo, 3DO and Xbox lines.

Mega Drive controllers are notable for being one of the first control pads to be ergonomically designed for the user's hands. Though improvements were made in the coming years, previous systems had cornered edges with their controllers, meaning they were often uncomfortable to hold after several hours of play. The Mega Drive controller is rounded, and has its buttons placed in easier to reach positions.

Variations

Control pads remained mostly the same across regions, but the colouring can determine the region and revision of the accessory. A minor addition added in the early 1990s is a little plastic lump on the B button, presumably to help users recognise where their right hand thumb was.

Early versions of this controller used the same internals as the original design, but later models have an improved D-Pad mechanism, employing a metal ball-bearing for the pad to rock on. This prevents wear which plagues the original design, which uses a plastic nub for the rocking motion and will eventually wear down with frequent use. Later versions employ a D-Pad with a two-piece fulcrum design as seen on the Six Button Control Pad and all Sega Saturn pads.


Technical Information

The chip inside the control pad is a 74HC157. This is a high-speed CMOS quad 2-line to 1-line multiplexer. Basically, how this works is there are two inputs ( A and B ) for every output ( Y ). There are four groups like this. There is one select signal for the whole chip. When the select signal is low, the output ( Y ) is the same as input A. When the select signal is high, the output Y is the same as input B. The pinout for the chip is as follows:

Pin 1 Select
Pin 2 1A
Pin 3 1B
Pin 4 1Y
Pin 5 2A
Pin 6 2B
Pin 7 2Y
Pin 8 Gnd
Pin 9 3Y
Pin 10 3B
Pin 11 3A
Pin 12 4Y
Pin 13 4B
Pin 14 4A
Pin 15 G (? must be low)
Pin 16 Vcc (+5V)

All the controls are done with switches. Up is a switch, Down is a switch, etc. The output is usually high when the switch isn't pressed. When the button is pushed, the output goes low. This is accomplished by connecting the output to +5V through a 10k resistor. The button is then attached between the output and ground. It looks like this:

    +5V -----/\/\/------+--------- Output
              10k       |
                        |
               /        |
  Ground -----/  -------+
             button
             (normally open)

The line numbers are determined as follows, looking straight at the plug on the front of the Genesis the numbers are:

	1 2 3 4 5
	 6 7 8 9
Line 1 Up output.
Line 2 Down output. These are the only two direct connections.
Line 3 Pin 4 of the chip. Output 1Y.
Line 4 Pin 7 of the chip. Output 2Y.
Line 5 This line brings in +5V. It is connected to the +5V bus line.
Line 6 (TL) Pin 9 of the chip. Output 3Y.
Line 7 (TH) Pin 1 of the chip. This carries in a select signal from the Genesis. This is a signal which varies rapidly and controls which input goes through the output.
Line 8 Ground. This is connected to the Ground bus line.
Line 9 (TR) Pin 12 of the chip. Output 4Y.


Now for the chip's pin connections:

Pin 1 Line 7 (select)
Pin 2 Ground (1A)
Pin 3 Left (1B)
Pin 4 Line 3 (1Y)
Pin 5 Ground (2A)
Pin 6 Right (2B)
Pin 7 Line 4 (2Y)
Pin 8 Ground (GND)
Pin 9 Line 6 (3Y)
Pin 10 Button B (3B)
Pin 11 Button A (3A)
Pin 12 Line 9 (4Y)
Pin 13 Button C (4B)
Pin 14 Start (4A)
Pin 15 Ground (G)
Pin 16 +5V (Vcc)

Reading

Access to the controller ports is from bytes $A10003 (controller 1) and $A10005 (controller 2). TH must be set for output and the other pins for input, so bytes $A10009 and $A1000B must be set to $40 to read the respective controller.

Bit 7 6 5 4 3 2 1 0
Pin - TH TL TR R L D U
TH = 0 ? 0 S A 0 0 D U
TH = 1 ? 1 C B R L D U

Bit 7 latches the value written to it. It takes approximately the equivalent of two nop instructions for other types of controllers (such as the six-button controller) to respond to a TH change.

External links

Physical scans

Mega Drive, JP (1988)
MDController SJ3500 JP Box Back.jpgNospine-small.pngMDController SJ3500 JP Box Front.jpg
Cover
Mega Drive, JP (1991)
MDController SJ3500 1991 JP Box Back.jpgNospine-small.pngMDController SJ3500 1991 JP Box Front.jpg
Cover
Mega Drive, US (1989)
MDControlPad US 3BV1 Box Back.jpgNospine-small.pngMDControlPad US 3BV1 Box Front.jpg
Cover
Mega Drive, US (1992)
ControlPad MD US Box Back 1992.jpgNospine-small.pngControlPad MD US Box Front 1992.jpg
Cover
Mega Drive, US (1993)
ControlPad MD US Box Front 1993.jpg
Cover
Mega Drive, EU (1990)
MDControlPad EU 3BV2 Box Front.jpg
Cover
Mega Drive, EU (1993)
MDControlPadEU93 back.JPGNospine-small.pngMDControlPadEU93 front.JPG
Cover
Mega Drive, CA (1989)
ControlPad MD CA Box Front Old.jpg
Cover
Mega Drive, CA (1993)
ControlPad MD CA Box Back New.jpgNospine-small.pngControlPad MD CA Box Front New.jpg
Cover


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Controllers Control Pad | Six Button Control Pad | 6 Button Arcade Pad | Arcade Power Stick 6B | Konami Justifier | MK-1470
Action Chair | Activator | Arcade Power Stick | Keyboard | MegaFire | Mouse | Mega Stick | Menacer | Remote Arcade System | Ten Key Pad | Third Party Controllers
Accessories 4 Way Play | Cleaning System | Control Pad Extension Cord | Genesis Speakers | Headset | HeartBeat Catalyst | Microphone | Region converter cartridges | Mega Terminal | Nomad PowerBack | RF Unit (Mega Drive 2) | SCART Cable (Mega Drive 2) | Stereo Audio Video Cable | Team Player | Video Monitor Cable | Third Party Accessories
Network services Sega Channel | Sega Game Toshokan | Mega Anser | Mega Net | TeleBradesco Residência | XB∀ND
Development tools ERX 308P | ERX 318P | Sprobe | SNASM68K | SNASM2 (Mega Drive) | SNASM2 (32X) | PSY-Q Development System (Mega Drive) | PSY-Q Development System (32X) | 32X CartDev | Sega Mars Development Aid System | Sega 32X Development Target
Unreleased Edge 16 | Floppy Disk Drive | Mega Play 1010 | Sega VR | Teleplay System | Video Jukebox