JOTEGO

Poll: PGM or CPS3

Esperanza is done with Taito's Extermination schematics. Which system should she work on next?

She will extract the schematics for the chosen system from a donated PCB. This is a step required for a precise FPGA core.

Development, System 16 and A. Pocket Update

Esperanza returned from holidays this week and she has resumed the work on Taito’s Extermination hardware. This was pretty much done before her holidays but as usual, small details take a long time to get done. She has been cleaning up the schematics and will be running electrical rule checks next week. The core for these Taito boards is quite advanced too, with the CPU and sound chips connected and operational. The graphics hardware is still not implemented.

Work on the NeoGeo Pocket...

Pocket: Ghosts’n Goblins

Sorry for the long wait, but this has been much harder than expected and you will see why soon! Today I proudly present a Pocketarcade core compatible with the Ghosts’n Goblins hardware. This core isthe same one working onthe other FPGA platforms. This means that JOTEGO supports now the same core running in seven platforms, without touching a comma in the core itself.

How to set up this beast? Well, I wrote this 2022-10-04 16:30:09 +0000 UTC View Post

Super Hang On beta

I stopped working on the Out Run core on the 18thof August after a frustrating debug week. The core was hanging up right at the start and I could not find the problem. I published the source code in the hope of another developer finding the problem. And open source worked its magic. Gyurco, who I have already mentioned in the past, is a developer from the MiST scene. He found the problem in a few hours. When he described it to me, it was something I had come across but I didn’t make sense o...

NeoGeo Pocket CPU: Test Coverage

For the last two weeks, Samuel has kept working full time on the NGP CPU. I asked him to use a FOSS tool called covered to check the test bench converage. But, what is coverage? In the early days of digital electronics the engineer had to manually calculate all the digital functions and choose individual logic gates (AND, OR, etc) to implement them. The design test was often done by building parts of it in discrete logic and testing on a real work bench. The ...

Karate Champ

The 80’s karate season starts today. Data East’s Karate Champ was an extremely popular game in the arcade and the home computer versions. I think we were all crazy about karate and ninjas back then. TV made it look normal to have a ninjagang in your neighbourhood. Karate Champ is a simple game in technical terms, even for 1984 it didn’t feature scroll and only had four colours per graphic element. Compared to Ghosts’n Goblins, which came out one year later, the technical difference is...

Extermination / NeoGeo Pocket

Español abajo / 日本語は下記

Esperanza finished Taito’s Extermination schematics today before heading for her holidays after her first year working for JT. During this time she’s extracted schematics for Konami’s Kicker, Konami’s Ping Pong, Data East’s Sly Spy, Gun Bird 2, SEGA’s System 18, CAPCOM’s Bowling and Twin Cobra. She’s taken measurements for Rastan, Konami’s Dark Adventure, Renegade, Konami’s 8-bit titles, System 16, etc. One year ag...

Roc'n Rope Beta

Although I had not planned to release a new game this week, I needed to work on something relaxing and chose to spend two days making an 8-bit Konami core: Roc’n Rope, designed by Tokuro Fujiwara. This is mix of a puzzle game and a platformer. You have to climb your way to the top where a phoenix waits for you. In order to climb, you use a rope. Fujiwara extended these mechanics a few years later on Bionic Commando. The conversion is based on the original schematics. It has a few custom chi...

Update on the Pocket

Esperanza spent her week finishing the Renegade PCB schematics. Although we think that we understand everything now, we want to let the schematics as correct and neat as possible for maintenance of original equipment and historical documentation. She still has a couple more days to finish them. The plan is to present the final version next Friday.

This week I took a detour and studied the Pocket documentation. I pretty much made the JTFRAME target files for the Pocket. Sadly, w...

Renegade Beta & Pang! Public Release

Update your jtbeta.zip key. Find it attached. The Pang! core has been promoted to public release.

Renegade is a game I had wanted to work on for a long while. I bought the PCB and had it sitting in a cabinet until this month. Esperanza started working on it and has already completed the sound and game CPUs. She’s still struggling with the graphics board and I think she’ll need to spend one more week to get all signals in place. I have attached the schematics to this post.

Even...

Out Run Jukebox

After three intense weeks, we haven’t been able to get Out Run to boot correctly. It boots to a halt but if you press F2, you can enter the service menu and play the tunes. So I suppose we have an Out Run jukebox core at this stage. The same goes for Turbo Out Run. With Super Hang On the situation is a bit better. You can actually start a game and move the motorbike but there is no road and the imaginary road ...

Support for Analogue Pocket

I saw an announcement by Analogue today talking about Open FPGA... I wonder if this means that they're finally going to open the platform to community developers. 

I was wondering if you would be interested in getting my cores working on the Pocket too. Supporting a new platform on JTFRAME takes some work, so I don't want to do anything that you, my patrons, won't like.

Should I port my cores to the Pocket (provided they open it)?

Out Run Progress & Renegade

Short update this week to tell you that work on the Out Run system continues. The game currently boots to a halt, although the service menu works. Too bad the built-in checks cannot find any problems with the core. I have moved my attention to Super Hang On, which is like Out Run but shares the sprites chip with System 16B. This one boots and goes through the demo loop, but the road is just a straight line, so it isn’t playable yet. Only the FM music works perfectly at the moment and PCM su...

Vigilante (public release) - SSF2T and other service releases

Español abajo - 日本語は下記

Many items to announce this week:

- Vigilante core promoted to public release. Source code here.

- Pang (beta core) supports bus contention when accessing video memory (better time accuracy)

- System 16: Dynamite Dux and Golden Axe slowdown fixed. Dynamite Dux wrong colours in second level fixed. I tried to finish the security MCU implementation in Sys...

Block Block / Dokaben / CAPCOM World

Español abajo - 日本語は下記

I was one to fall for the simplicity of Arkanoid in my 8-bit home computer. I thought with the first two Arkanoid games, the series was over and didn’t give credit to any other block game. Then I came across CAPCOM’s Block Block. This game brought fresh air to the genre five years after the first Arkanoid was released.

Although the basic rule is the same: don’t let the ball fall, it adds many new elements that enrich the g...

CAPCOM Bowling Schematics Ready

We have completed the schematics extraction of this track ball game. It is a very interesting piece of hardware because it comes from CAPCOM but uses only standard devices. Unlike the Pang! hardware, where you could see some CAPCOM custom chips shared with 1943 and other games, this bowling game seems to have been engineered by a completely different team.

The game uses two m6809 CPUs. This CPU was not popular among computer enthusiasts in the 80’s because the C64 and the ZX Spectrum ...

Super Pang (support added to JTPANG core)

Super Pang

After the warm receiving Pang! got last week, I am very glad to bring Super Pang today. The game runs on the same board with small configuration changes so it wasn’t too hard to make it work. The core itself supports the hardware better but there are still a couple of things to iron out. There will one more beta about this hardware, probably next week, adding more games and improving the current ones. The FM synthesizer sounds better this week, but it still...

Pang!

This game, with no large demons, no hero plot and not even screen scroll, is one of the most enjoyable arcade titles ever. Show it to any kid and they’ll love it too. Pang! is also an interesting title because the hardware was developed by CAPCOM, and they also published games for this 8-bit platform. As I have done many CAPCOM systems, I was interested in this one from the technical point of view too.

The system clearly targets low cost: only two graphics layers (fixed background and...

NeoGeo Pocket Update

I have been working exclusively on the NeoGeo Pocket for the last two weeks. I have the instruction set implemented for the CPU now, with the exception of the three instructions related to interrupt and micro-DMA processing. The CPU logic takes at the moment over 3.7k lines of code. This is surprisingly less than the Z80 core that we use (4.3k lines) even though this CPU is like a 32-bit Z80 plus a bit of DSP functions. I also wrote140 assembler programs to test the different instructions and...

Vigilante (beta)

NB: The files are available in JTBIN via update_all or in the #betafiles Discord channel

Vigilante is a game that goes with no presentation. Everyone remembers the satisfying sound that kicking and punching produced in this title. But let me talk to you about some technical curiosities:

- The game still useda Z80 as the main CPU in 1988. As this CPU was starting to be a bit slow for the increasing demands of arcade games, the engineers made a trick for the second scroll layer. Ins...

The Speed Rumbler/Twin Cobra/Robocop…

The Speed Rumbler

- Extracted layer priority circuit from PCB and fixed the FPGA core with it
- The screen had an 8-line offset, which is corrected now
- The sprites position was slightly offset too
- There was a noisy line when the game was in flip mode
- The default sound balance had the FX too loud

After this, there are no known issues for this game.

DEC0 System (Robocop, Dragon Ninja…)

- This system has been shiftedto...

Ghosts’n Goblins Color Flash

A couple of years ago, someone wrote me asking about yellow flashes in Ghosts’n Goblins game PCBs. I thought it was due to some timing problem in the aged hardware, which probably just got worse with temperature as the board got powered for longer time. However, this week I came across a video from an original PCB that showed this yellow flash effect. It was very prominent. I remembered then that the GnG hardware has a design flaw: it is possible to corrupt the palette memory if the CPU tri...

Track & Field (beta)

This is the original button smasher: Track & Field. We have already seen a sequel to it: Hyper Sports, and we visit the original this week. This board was donated by Gyrrus about a year ago along other ones. He was worried it was taking too long to deliver the core, but it’s finally here. These things just take time. We also approached the hardwarestarting with Kicker, and working our way through more complex boards. There are still a couple of related systems we want to do.

Track...

Rastan Saga

Important note: Road Fighter, Konami’s Ping Pong and Hyper Sports are promoted to public releases today. For the other games in beta phase, you will need a new beta key (jtbeta-zip). The new key is attached to this post, copy to MiSTerFPGA’s games/mame folder. Do not unzip it.

We come back to the 16-bit arcade world this week with a real classic: Rastan Saga. This game has an incredible if short sound track, that takes out the barbarian you have inside. And what did the gam...

Konami's Ping Pong

Following on the Konami series of games before Contra, we have done an in-depth research on Konami’s Ping Pong (GX555). Super Crow provided us with an original PCB. We extracted the full schematics for it, measured the custom chips and wrote a custom firmware to execute on the board to test some assumptions. Please see the full report attached to this post. The report covers the different aspects that should be addressed when converting arcade games to FPGA, particularly those thin...

Hyper Sports (1984)

As you may know, I’ve spent most of the week working on the NeoGeo Pocket core. I’ve been implementing the video subsystem before hooking it to the CPU. The CPU module is not complete yet but it’s good enough to try connecting it.

There was also time to add support for Hyper Sports to the Road Fighter core. Although strictly not the same board, the two games are very similar in terms of hardware. Road Fighter didn’t have the PCM voice chips soldered and there is a jumper on the ...

Road Fighter Files

Find the Road Fighter beta files attached. Remember that you can get them easily by using the update_all script. They are also available in the #betafiles channel in our Discord server.

Road Fighter

Konami knew what made a great arcade: a short introduction, clear rules and fast gameplay. Road Fighter is a clear example of that recipe and it worked well in home ports too. The NES and MSX version are dearly remembered by many users.

There’s an interesting technical quirk about this game. The game field is vertical, with a scroll going from top to bottom. However, Konami used the same custom 085 chip to handle the scroll as they had used it in Kicker. That chip was designed to hand...

Sly Spy & Boulder Dash 2

Sly Spy

This secret agent was due to visit us last week, but apparently he had a sabotage mission to do first! It took me four days of debugging to find out why the game wasn’t booting up. In the end, it was a single line missing. Once added, the game run without any need for more edits. That’s the world of digital design: one or zero!

If you haven’t played Sly Spy but liked Shinobi, give it a go: it will surprise you. This is a game easy to master, probably...

Research & Development

We spent the week purely on research & development activites. Esperanza got quite far with the Sly Spy schematics (see the attached file) and I implemented 15 more instructions in the NeoGeo Pocket CPU. The CPU has now about 80% of its instructions implemented. I think the CPU needs two more weeks, and then I can start working on the rest of the NeoGeo system.

For Sly Spy, we will see the results next Friday. The plan is to leverage the current DEC0 core (Robocop, etc.), and the inf...