Jump to content
IGNORED

The 7800GD (New 7800 Flash Cartridge?)


SainT

Do you really want one?  

166 members have voted

  1. 1. Would you be interested in buying a 7800 SD cart (expected price around £60-£70)?

    • Yes
      159
    • No
      7

This poll is closed to new votes

  • Please sign in to vote in this poll.

Recommended Posts

8 minutes ago, DrVenkman said:

I use a Phaser with a home-designed inverter on the trigger. No accuracy problems for me. :)

Does the phaser not shoot to the left? This video here of someone using the SMS Phaser with a MiSTer setup is exactly the behavior I see from a SMS Phaser on real hardware.

 

https://streamable.com/sz9zwe

 

The output from the SMS Phaser for the detection of the electron beam is actually earlier than the game is expecting. So either the game is designed to shoot to the left, or the SMS Phaser has less delay than the 7800 official light gun.

 

I'd be interested to see a video of the accuracy of your 7800 and SMS Phaser.

 

And the way the trigger works has no bearing on the accuracy, this is just the direct input from the beam detection circuitry into the 7800. I guess it's possible caps have failed over time, causing less delay... 🤔

Edited by SainT
  • Like 1
Link to comment
Share on other sites

I have no idea how it would be possible to make a video showing the accuracy, to be honest. I just point at the target and pull the trigger. Maybe it’s an NTSC/PAL thing?  I also know Sega LightPhaser internals look pretty much identical to the 7800/XE-styled guns Atari produced aside from the inverted trigger signal. They’re really not very complex. 

Link to comment
Share on other sites

19 minutes ago, DrVenkman said:

I have no idea how it would be possible to make a video showing the accuracy, to be honest. I just point at the target and pull the trigger. Maybe it’s an NTSC/PAL thing?  I also know Sega LightPhaser internals look pretty much identical to the 7800/XE-styled guns Atari produced aside from the inverted trigger signal. They’re really not very complex. 

Just hold your phone behind the gun and pull the trigger a few times while recording. The video linked above showed the accuracy with the MiSTer setup very well -- off to the left by a good margin.

 

Likewise I did the same, this is a single frame from the video showing where I point the gun (post and v lined up), you can see clearly it shoots where it's pointed. Before modifying the game code, it was off to the left as the MiSTer video. This is also NTSC.

 

Image

 

Edited by SainT
Link to comment
Share on other sites

@SainT I believe the accuracy of the lightguns also varies from game to game. I remember my XE lightgun not being very accurate to me as compared to joystick controls on Crossbow for instance. But with Alien Brigade it was much more accurate and I was able to finally beat the game using a light gun whereas I never could with joystick control. 

 

So I can't speak for the SMS modified light guns, but my XE lightgun does vary on the accuracy depending on the game it is used with.

 

  • Like 2
Link to comment
Share on other sites

We’ve all been all over the relative accuracy stuff before in multiple threads. I don’t have an Atari branded one to compare, but when I took my Sega Light Phaser apart to repair and clean, the internals looked very, very similar to photos I’ve seen of the ones Atari sold. I would not be at all surprised if they are the same aside from the trigger circuit, since they also use essentially identical plastic cases. Knowing how Atari did stuff, and Sega being of the same era, I would expect both company’s units were likely all made by the same third-party supplier/factory.  In any event, these devices also have a little lens and photodiode and I’m certain it’s possible one or both of those can get slightly misaligned due to abuse, manufacturing tolerance, or whatever. 

 

 

Link to comment
Share on other sites

Anyone who wants to spend some time finding cheats for games with something like a7800, just let me know what needs modifying and I can add it into the cheats. Or you can create your own, just pass the file over to me to test until you have a 7800GD! :) An example of a few cheats for Dark Chambers (courtesy of Gent over at EmuCheats) and the light gun calibration for Crossbow:

 

#$dba8f21c				; Dark Chambers NTSC ROM CRC (not header)
[Infinite Health]
:FRAME					; executed every frame, only low RAM writes valid
@<$1933=$9f,$9f				; player 1 and 2
[Infinite Keys]
:FRAME
@<$192d=$9f,$9f
[All Upgrades]
:FRAME
@<$1931=$e0,$e0
[Infinite Bombs]
:FRAME
@<$192f=$05,$05

#$24227e7e				; Crossbow NTSC
[Light Gun Calibration]			; cheat option, will always have ON/OFF
?[Offset]=B{0-7}:3			; parameter, can be altered in-game, range 0-7, default 3
:ON					; on action
@$d3b=$d0,[Offset]			; bne offset
:OFF					; off action
@$d3b=$ea,$ea				; nop nop

 

Cheats are togglable during play, so it's good to have an ON and an OFF for ROM patches. If it's a RAM patch (:FRAME) then it's executed every frame, so turning it off just stops the write.

 

In time I will write some host side code to validate cheats and generate CRC's from ROM's to make life easier.

 

#$xxxxxxxx

Starts a set of cheat options for the ROM with matching CRC (ROM data only, not header).

 

[xxxx]

Starts cheat option named xxxx in menu.

 

?[xxxx]=T{x-y}:d

Parameter for the current cheat option, named xxxx in menu. Must precede any cheat block.

Can optionally have type, range and default value specified after =.

Without specifying, it is set as byte, 0-255, default 0.

T is type (optional)

UB/B - unsigned byte

SB - signed byte

E - enumeration (to come...)

{x-y} is range (optional)

x is lower bound and y upper.

:d (optional)

Default value for option, if omitted this is 0

 

:(FRAME/ON/OFF)

Start of block to execute when cheat is turned ON, OFF or once per FRAME.

Commands within cheat block:

@xxxx, @<xxxx

Set address to write to, can be in ROM with @xxxx or in 7800 address space with @<xxxx

When using a FRAME cheat, only 7800 address space writes are valid.

=xx,=[xxxx]

Write byte xx or parameter [xxxx]. Multiple bytes (parameter or constant) can be specified with a comma delimited list.

xx

Any constant can either be decimal, binary or hex. For binary precede the constant with % and hex $.

 

Edited by SainT
  • Like 9
Link to comment
Share on other sites

You can hold down down plus fire for a couple of seconds to enter the break menu with a CC40. I’ll see about break on the second port, at the moment I don’t poll this port due to it messing with vox / savekey. However if the header doesn’t say it uses the vox / savekey I could poll the second port too…

Link to comment
Share on other sites

On 5/10/2023 at 9:26 PM, gambler172 said:

Now I need an invisible cheat for Scrapyard Dog.

Invisibility or Invincibility? 

 

For invincibility, shields would need to modified to an infinite amount or/and never decrease when hit. 

 

The game starts with the player having already one shield in their possession, and is why when the first hit occurs, the player does not die, just stops 'flashing':

 

image.thumb.png.6f68c626f256b74b49af4d619392ffad.png

Link to comment
Share on other sites

I can't wait for this and the GameDrive to be available (Anyone want to buy my Concerto?)
I hope that something can be done with the Mega 7800 being read in port 2 (or a splitter cable?) because Pac Man Collection with a joypad is not my idea of fun

  • Like 2
Link to comment
Share on other sites

6 minutes ago, mimo said:

I can't wait for this and the GameDrive to be available (Anyone want to buy my Concerto?)
I hope that something can be done with the Mega 7800 being read in port 2 (or a splitter cable?) because Pac Man Collection with a joypad is not my idea of fun

The Mega7800 works just fine in port 2, it's just the BREAK functionality that was limited to port 1. However I sorted that yesterday, you can break from port 2 as well now! It turns off checking for the Mega7800 in port 2 if the game is flagged as having SaveKey/Vox support as writing anything to port 2 (which the Mega7800 requires) screws up the SaveKey/Vox support. You can however still break using the standard pad method of DOWN+A+B for 2 seconds. :)

Edited by SainT
  • Like 5
  • Thanks 1
Link to comment
Share on other sites

42 minutes ago, mimo said:

I can't wait for this and the GameDrive to be available (Anyone want to buy my Concerto?)
I hope that something can be done with the Mega 7800 being read in port 2 (or a splitter cable?) because Pac Man Collection with a joypad is not my idea of fun

There are at least these six joystick controllers readily available for the Sega Genesis that would work just fine with the Mega 7800:

 

-Sega Genesis Arcade Power Stick Joystick Model 1655
-Sega Genesis 6 Button Arcade Stick Model 1627 Joystick
-Asciiware Power Clutch SG Controller Joystick Model 5700 Sega Genesis
-Asciiware Fighter Stick SG-6 Joystick Controller Model 5720 for Sega Genesis

-Quickshot Sega Genesis Megadrive Maverick 3 Joystick
-Quickshot Sega Genesis Megadrive Maverick 3+3 Joystick

 

Prices range from as inexpensive as $20.00, to ~$100.00, a few dozen available 'new' currently on ebay.

  • Like 2
Link to comment
Share on other sites

You can, of course, buy brand new Mega Drive controllers such as the "Retro-Bit Official SEGA Mega Drive Controller 6-Button Arcade Pad" as well! Which is one I have tested it with (admittedly a pad not a stick!).

 

The Mega7800 also support Master System controllers if you happen to have any of those. I've tested it with one of the control sticks. :)

Edited by SainT
  • Like 3
Link to comment
Share on other sites

Of course I could buy something else, but I'd rather keep using my home made sticks or the decent quality ones I have already amassed than spend even more cash and add to the clutter I already have 

Link to comment
Share on other sites

1 minute ago, mimo said:

Of course I could buy something else, but I'd rather keep using my home made sticks or the decent quality ones I have already amassed than spend even more cash and add to the clutter I already have 

If you have master system or mega drive sticks then you can use either in either port. :)

Link to comment
Share on other sites

  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...