JOTEGO

Analog Audio Circuitry

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Analog circuit design remains an enigmatic discipline that has, to date, evaded the expansive reach of ChatGPT and similar technologies. It's therefore not entirely surprising that analog circuits represent the most overlooked element of arcade PCBs (Printed Circuit Boards). Yet, digital-to-analog conversion is essential for producing video and audio outputs. We have incorporated universal support within JTFRAME (the framework for JT cores) to define the ...

1942/1943 and Work on Audio Filters

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Arcade video games have three types of sound sources:

1. Square/triangular waveforms at different frequencies: PSG sound (1942, Exed Exes, Kicker, Track'n Field...)
2. Sine waves modulating other sine waves in frequency: FM sound (Street Fighter 2, Shinobi, Out Run...)
3. Digitised sounds: PCM sound (Drums in Out Run, the title song in Teenage Mutant Turtles...)

All these sound sources are produced digitally. We can  ...

Vendetta (Crime Fighters 2)

Last minute release today, please excuse us for the short  post: we've managed to get Vendetta working in the JTSIMSON core. The  hardware is extremely similar between the two systems, although they are  incompatible. You cannot just swap the ROM chips from one to the other  and get them working. The devices are mapped to different CPU addresses  and there are a couple of hardware changes. For example, Vendetta has a  custom chip to detect sprite collisions (and ...

Parodius da!

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We worked on Parodius da! schematics last year. It turned out to be very similar to The Simpsons board, with some differences:

• Different sprite chipset: 053244/5 instead of 053246/7. This chipset  is very similar but only supports half the sprite count of the Simpsons one. Sprite scaling uses a different range and there are some small  changes in what configuration bits mean that brought a bigger headache &...
  2024-02-09 10:48:34 +0000 UTC View Post

Body Slam / Quartet / JTALIENS release

Thanks for the feedback on last week's service release.  Some regression errors were quickly identified by the community and  appropiate patches have been applied:

• Double Dragon 2 music stops
• Pop sounds in CPS1
• 2024-02-02 16:29:43 +0000 UTC View Post

Service Release

Thanks to everyone who has taken the time to report an issue in GitHub. All files have been updated in JTBIN. You can run your favourite MiSTer/Pocket updater or grab the files manually.

This service release tackles the following issues:

JTSHOUSE (Splatter House)

• 2024-01-26 10:03:54 +0000 UTC View Post

Global Core Review and Issue Solving

As most of you know, issues related to JTCORES are collected here.  This includes road map items, reverse engineering activity, core  enhancements and bug fixes. After the NeoGeo Pocket core release, I  decided to take some time to clear out the issue list as much as  possible. Other scene developers are helping with this, funded by your  pledges to this Patreon. The list was over 70 issu...

NeoGeo Pocket Beta Core

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Just in time for reyes,  the first beta core for NeoGeo Pocket is available for MiSTer and  Analogue Pocket in the usual locations. Sadly, this core does not fit in  smaller FPGAs, like SiDi or MiST because of internal RAM size  requirements. Some notes:

• Only the monochrome color is supported in this release. 2024-01-05 10:22:45 +0000 UTC View Post

NGP Development Update / 1942/Higemaru for Pocket

2023-12-29 NGP Development Update / 1942/Higemaru for Pocket

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NeoGeo Pocket Update

The NeoGeo Pocket core is the worst time to market from my career. I have worked on and off on it for the last two years.  During some months, it has been the main focus. I also tried to have  three different developers work on test tasks on the system CPU and the  whole core with little results. Sadly, after two years, the NGP core wa...

MCU Time! Bubble Bobble, Tokio, Renegade...

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When I made the JTBUBL (Bubble Bobble, Tokio) core, I had  to limit it to certain game versions that used a MCU (Micro Controller  Unit) for which I had found a Verilog module. That meant putting the  original Tokio version aside and working only with the bootleg. The same  happened with Renegade too, where I had to hide the MRA for the  original version and use one for a bootleg instead. Not only that was a  limitation I did...

Thunder Cross, Space Odyssey and Keyboard Support on the Pocket

Thunder Cross

JTALIENS core gets support for one more game: Thunder  Cross. This is a spectacular shooter with a good depth feeling thanks to  the use of parallax scrolling and sprite scaling. As in Nemesis, you  get options to fly along your ship. These options can either shoot with you or use a special shoot, depending on the powerups you get.

This game works on almost the same PCB as last week's Gang Busters, except for...

2023-11-17 Gang Busters and Public Releases

The JTALIENS core receives support for a new game added this week: Konami's Gang Busters.  This is a cute two-player game that reminds of Labyrinth Runner and  CAPCOM's Avengers. The cop duo of the diminutive Smith and the taller  Wesson (over the pistols Smith & Wesson), who can't help but shoot  when they have a gun, shoot, shoot, shoot to protect their town from  bank robbers RED GANG! This is Konami's signature character shooter  game. It...

Unplayable? Only credits?

Unplayable?

If you see the core credits rolling through the screen but cannot play then:

1. If you cannot see the game attract mode behind the credits, then you are missing the game ROMs
2. If you can see the game running but cannot insert coins then you are running a closed version of the core

Cores have three versions:

2023-11-07 14:42:38 +0000 UTC View Post

More Halloween Games

Today is Halloween so we are going to introduce five Halloween-ish games. All of them are playable on multiple FPGA platforms through JT cores. Try them out if you haven't already!

First up is Haunted Castle, released by Konami in 1988, a rare reimportation from a consumer console to an arcade game. The gothic horror worldview was further refined in the arcade version, with wonderfully enhanced graphics and sound. In stage 3, while the famous song 'Tears of Blood' is pl...

Halloween special: Splatter House

Important: jtbeta.zip changed, you need to update your copy.

I used to believe in Christmas miracles, now I have to believe in Halloween miracles too! Just five days ago, the JTSHOUSE core was unplayable and with completely broken music. I thought that having this beta release was a long shot, but here we are.

The main difficulty, as I explained before, has been the microcontroller (MCU). I had assumed it was based on a different CPU, and later on found that it wa...

FPGA Platform Poll

As there has been a recent surge in Patreon subscribers (thank you!) let me ask you about which FPGA model you are using. Select as many as you own. Note that multiple choice may only work through a web browser.

Bubble Bobble (MiSTer update), CPS15 (Pocket/beta), CPS2 (Pocket/public)

Work on the Splatter House core continues. The game graphics are correct and the demo is stable and does not hang up. But, the MCU seems not to be working correctly and as a result, the coin inputs get locked randomly. It looks like the days until Halloween are going to be scary to me as a developer!

One of the reasons behind the MCU not working was that the HD63701V MCU is binary compatible with the Motorola MC6801 CPU. So I was basing my MCU implement...

Dragon Ninja and news

Quick update:

• Namco System 1 core is coming up soon. A couple of iconic games for it are Splatter House and PacMania. Currently the logic is hooked up but there is some problem at boot up. I’m targetting this one for Halloween
• As a side effect of this work, the MCU implementation for Double Dragon is better now. An occasional bug halting the game at the memory check screen is fixed for good
• JTTORA (Tiger Road) for the Pocket, is promoted to Public Release
...
2023-10-06 15:00:38 +0000 UTC View Post

Out Run/Super Hang On Update & Development News

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Service Release

JTOUTRUN update: (Out Run support)

• Fixed odd line in the middle of the road
• Fixed PCM sounds
• Fixed OSD menu (MiSTer)
• Added automatic saving of service settings (Pocket)

JTSHANON update: (Super Hang-On support)

• Fixed odd line in the middle of the road
• Added automatic saving of service settings (...
  2023-09-22 15:32:36 +0000 UTC View Post

Punk Shot (JTTMNT new beta)

The Pocket files have been corrected and are available at JTBIN 

Konami used to roll new chip versions frequently and even merge two or three generations together. For Punk Shot, part of the TMNT graphic chips are used, but others are new. For instance, the layer mixer that gives different priority to each part of the background or sprite is a new chip, the...

The Final Round

Important note for Pocket users

In order to facilitate the installation of beta cores, this will be added to JTBIN from now on. Third party updaters will take them from there and add it to your Pocket, which is more convenient. But, you will need to manually unzip the jtbeta.zip to the folder Assets/jttwin16/common and to the folder Assets/jttora/common. Otherwise, the core will  show the credits screen continuously and keep the co...

MIA (Green Beret 2) beta and fixes

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Following last week’s Teenage Mutant Ninja Turtles' beta, we add support to MIA (Green Beret 2) to the JTTMNT core. The two arcade PCBs are very similar, but TMNT was a more expensive system. It had more chips and memory for sound and the video ROMs were larger. MIA feels like a vitaminated Green Beret where the essence of the original has been kept. Even to the point of keeping th...

Teenage Mutant Ninja Turtles (beta)

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As you probably all know, Furrtek made an awesome research work on the Konami chips used in the TMNT arcade game. These chips are used in other games and I had made my own version of them based upon his detailed findings. The JTALIENS core uses those chips, for...

The Simpsons (beta), Black Tiger (Pocket, public release)

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MiSTer users: update your jtbeta.zip file using the attached one

The late 1980s and early 1990s marked a dynamic era for both video games and popular culture, with iconic franchises leaving an indelible mark on us. Among these, "The Simpsons" stood tall as an animated powerhouse that seamlessly blended humor, satire, and societal commentary. Konami harnessed the zeitgeist by releasing The Simpsons arcade game i...

Development Update

The NeoGeo Pocket core is taking most of our time at the moment. All monochrome games boot up now and are somewhat playable (see details here) but they all have problems and the core is only working on MiSTer at the moment.

I didn’t know the system before and I am quite surprised at the quality and personality of the titles. As it happens, this hardware has some odd tradeoffs. P...

System 16 Service Release

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I developed the SEGA System 16 compatible cores in 2021. It was a difficult project because under that unifying System 16 name there are indeed many different arcade boards. For a starter, you have two different sprite and PCM sound approaches for the early System 16A boards and the later 16B ones. But even within the A and B models, there are many different protection systems. Some games have no protection at all, others have an Intel ...

Crime Fighters (beta), HCastle (release) and hotfixes

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Another week with too many things to talk about. Let’s just focus on the highlights

• New game in the JTALIENS core: Crime Fighters. This is a Konami brawler, quite fresh and less politically correct than previous Konami games, allegedly because of the change of era in Japan from Showa to Heisei. Check out the 4-player version in the alternatives folder. Thanks to the JTALPHA team members: Atrac17, ...
  2023-06-30 17:05:18 +0000 UTC View Post

System 16B (Pocket) and NeoGeo Pocket Update

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The NGP core saw good progress this week with the first successful boot on MiSTer FPGA. Almost all the monochrome NGP system is implemented now, missing only the horizontal blank interrupt and the DMA logic. The cartridge interface (based around flash memory chips) is going through the debug phase now.

Because of NGP’s particular video format, we may only see versions of this core for MiSTer and Pocket. Other machines (MiST, etc...

Super Contra (JTALIENS) beta

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As promised, we will have a long run of Konami compatible cores either based on the Konami CPU or the TMNT video chipset. Super Contra joins the club today as part of the JTALIENS core. The largest difficulty in adding support for this system has been a bug in the CPU implementation. This is similar to the problem in the NeoGeo Pocket core where a CPU bug halted last week’s beta. I have spent one week improving the workflow for findin...

NeoGeo Pocket Update

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Today is the deadline I had set for the NeoGeo Pocket beta. I set this deadline to force myself to focus solely on this project. The core has seen a lot of progress and it boots up and runs through the language and clock set up screens. However, it hangs up soon after. The video accompanying this post comes directly from the JTNGP core.

During these three weeks I fixed several bugs in my T900H CPU core and also implemented other p...