How a Konami Cabinet Stays on Target: Target Panic!

We’ve seen a few test PCBs now; games that were only sold alongside Japanese arcade cabinets to satisfy a law requiring a minimum amount of functionality. Sega gave us Dottori-kun, a remake of Head-On; Taito gave us Mini-Vaders, another retro throwback. But what about Konami? Let’s test out our system with Target Panic!

No Expenses Spent

Konami’s Target Panic is a small densely-packed PCB, intended presumably to be sold alongside cabinets like the 1996 Konami “Windy”. We haven’t seen a Konami game from 1996 on the blog yet, but it’s fair to assume they did better for their retail games than a Z80 CPU. (A CMOS Z84, as it turns out) Interestingly, the position that would be taken up by a crystal oscillator is vacant on this board.

Of course, a CPU needs a system clock. Konami just went with a cheaper option– a ceramic resonator rather than a crystal oscillator. For reference, a random datasheet for a ceramic resonator gives a frequency tolerance of up to ±0.5%. A totally random crystal oscillator, on the other hand, measures its frequency stability as ±50ppm– that is, 0.005%. While these aren’t the exact parts used, two orders of magnitude less stable sounds about right.

Now, that would definitely be enough to cause some problems for a composite video signal’s colorburst. It might also just barely be audible to a human with perfect pitch, if there was a sound chip and depending on the frequency. But this is an arcade PCB intended to be run on 90’s cabinets, with RGB CRT monitors, and there’s no sound chip. Obviously Konami considered it worth the tradeoff, though both Sega and Taito used crystal oscillators.

Let’s do some comparisons between the three PCBs.

Dottori-kun<br>Mini-Vaders<br>Target Panic

Year of release<br>1990<br>1992<br>1996

Main oscillator<br>4MHz crystal<br>24MHz crystal<br>4MHz resonator

Main CPU<br>4MHz Z80<br>4MHz Z80<br>4MHz Z80

Resolution<br>128x96<br>256x224<br>192x96

Colors<br>8 (2 per screen)<br>Monochrome<br>8 (4 per screen)

RAM<br>2kiB<br>8kiB<br>8kiB

It’s worth noting that I believe all three PCBs stall the CPU for at least some of the time during the active display, so the 4MHz is more of a theoretical maximum. Similarly, the four colors the Target Panic can draw are actually limited, as black and white are hardcoded. Despite spanning half a decade and three separate companies, the hardware specs barely changed. This was how you made a bare minimum game.

Both Dottori-kun and Mini-Vaders are based off of one of their respective company’s popular 1970’s arcade machines. Konami only really started to get into their stride in the 1980’s, though, so what did they turn to here? Well, they didn’t just dig into the past of their games; they dug into the past of arcades and amusements. (Sorry, Astro Invader diehards)

The game

The first thing I want to say is that despite any concerns you might have from the ceramic resonator, I had absolutely no issue syncing this device with my capture setup. So points on that, Konami; thank you for thinking of people playing your game decades later on hardware it most certainly was never intended to run on. Or for having it coincidentally work. I’ll take either.

The test

Before we start, let’s look at this self-test. This was a hard screenshot to get; I had to time it pretty much perfectly, it only lasts about as long as the Framemeister takes to sync.

Of course, I could've used the OSSC Pro or GBS-Control in a free-running mode. But this was easier than setting those up.

So, this might not be worth mentioning. Most arcade games start up with a self test, it’s just good practice. But let’s go back to the part where I say that it was extremely fast. Take a look at what the MAME source says:

Konami Target Panic (cabinet test PCB)<br>It takes a while to boot up, just hold INS for a bit to fast forward.

And if you load the ROM in MAME, you will indeed be stuck on the test screen for quite some time before it finally lets you play the game. What’s interesting is, I dumped my ROM just to be sure, and it’s byte-for-byte identical. So this must be waiting on some edge case that isn’t emulated yet. Proof that even tiny boards can have complications for emulating.

The presentation

Target Panic has the most proper title screen out of any of the arcade test PCBs I’ve looked at so far. Not only does it actually show the name of the game (something both Dottori-kun and Mini-Vaders failed at), it even has copyright information, and a trademark symbol. Apparently Konami’s lawyers are very thorough.

One thing I found interesting are these vertical lines that are visible in the full capture. My guess is that these are gaps in the pixels, nearly instantaneous as the 74LS157 or other logic in the chain clocks out the bits. Worth noting I couldn’t see that at all on my Sony Trintron, but it might just because it’s so small.

No really, the game

So what is Target Panic?

It’s a simple game where one of the eight targets that surround the screen will rotate...