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PC Engine CPU

jsgroth.dev

147 pointsibobev71 comments

The PC Engine CPU is highly underrated. People like to go "haha, it was the TurboGrafx-16 but its CPU was 8-bit" like that makes it a joke, but that clock speed boost on top of the 6502 architecture is a big deal. (The S-CPU on the SNES still has an 8-bit data bus too, so the 16-bit advantage isn't as strong as it seems)

The Arcade Card add-on was designed specifically around using the transfer instructions to rapidly transfer graphics into VRAM, something it was very good at. Made some really good Neo Geo ports possible.

>"haha, it was the TurboGrafx-16 but its CPU was 8-bit"

Amusingly, TurboGrafx-16 is a US-specific name, so is the huge shell.

In Japan, the console was called PC Engine and was really compact. Later revised as CoreGrafx and CoreGrafx II, both still the same fundamental hardware.

I own the later variant. Very solid little box that sips power and produces stable a/v output.

NEC made some great looking consoles, in Japan. The PC Engine, the PC Engine Shuttle, the IFU-30 unit "briefcase", and the SuperGrafx. I think console design peaked with the SuperGrafx.

In the back of my mind, I have the idea that US regulations required extra shielding that the Japanese model lacked. Maybe this isn't the case. Maybe some American marketer decided it was just too cute or too small.

I think the redesign of the NES shell for the North American market was largely for vanity reasons, wasn't it? Entertainment system instead of computer, grey plastic instead of beige, front loading instead of top, long cartridges that were supposed to look like VCR tapes instead of toys.

N also took the opportunity to remove the lockout chip, since the system came out so late in the lifecycle and they were largely successful at stamping out unlicensed releases.

The Japanese version of that redesign also got compatibility with existing SNES Multi-AV cables (at least the composite ones, the AV Famicom didn't output s-video) while the US version was RF-only (and AFAIK is worse for jailbars than any previous NES)

They described the 1st NES changes from 1st Famicom.

Oops, I misread and thought they were talking about the re-redesign near the end of the NES' lifetime.

My understanding was that after American retailers were burned so hard by the Atari crash, Nintendo wanted to position the NES as far from a 2600 as possible.

Which, despite the VCR-like appearance, meant no faux wood detailing ;-)

When I was a teenager, I had a hobby of importing Japanese gaming consoles and video games.

I had a PC Engine and a Super Famicom (well before the SNES made it to the US!). They both had cosmetic differences but I thought that the Japanese versions of both would be more attractive to US customers. I'm not sure why they shipped different casings like they did.

Presumably you were in the USA? We had grey imports in the UK too, but it was prohibitively expensive. My family was relatively well off, but no way I'd have been able to wangle an expensive import super famicom.

Even worse when the snes did finally arrive we were stuck with pal 50hz squished slow versions, especially noticeable in street fighter 2.

Yep, I was in the US. IIRC, the Super Famicom cost me about $350-$400 at the time. Also had the .jp version of the Neo Geo, which was even more. And the PC Engine and Famicom. I did some tradings between consoles there. We weren't well off but all my job money went into it.

For the SNES, from what I heard it was partially because with the flat topped NES, Nintendo of America got a lot of repairs from kids spilling soda or whatever on the NES they were using as a table. For the SNES, they deliberately made it harder to that.

I've got a TurboExpress. Recapped, it's a great little handheld. Screen is adequate for the era (though I've seen upgrades). My favourite 6502-based handheld is still the Atari Lynx, but this is close.

I have a lynx II, and it is a brick (huge! heavy!).

The amazing Street Fighter II' port didn't even need any add-ons! (Well, aside from the 6 button controller)

The article notes that the cartridge had some extra bank switching inside it though, as it went over the address space limit for HuCards.

If they had just let you remap the controls so you had fierce and round house, the two button controller would have been serviceable. All the ports of that game are good. I’ve compared them side by side (SNES, Genesis, PCE) and they’re frankly all fun.

I did have a PCB worked up that lets you convert anything to a PC Engine controller. Can’t give them away!

All ports by capcom are good :) which means all console ports (apart from the sega master system port, which is impressive just not by capcom). The Amiga, spectrum etc etc ports were god awful.

Though apparently the super street fighter port on the Amiga is rather decent.

I'd love to read something in depth about the capcom console ports. The snes, magadrive and pc engine ports all look like some minor miracles! I remember an interview with a snes developer at rare were he said sf2 is the most impressive game on the snes. (Think I read that in retro gamer UK mag in the last decade or so).

The PCE (and by extension, TG16) proved that outside of games that relied on high processing speed (3D games like Elite, or sports games), 8-bit CPUs could give every bit as compelling an experience as 16-bit chips.

Wonder what a good programmer could do with a modern 6502-based ISA clocked at 20+ MHz but otherwise identical hardware to <insert favorite 6502-based platform here>. Imagine being able to hit I/O registers on every single hardware cycle because your CPU blows that out of the water (see: SuperCPU on C64/128 which can very much meet the demands of "write a new value each 1MHz cycle")

Dream big. Imagine what we could do with a 5 GHz 6502.

Of course, the memory would need to be on the same die to be able to function at that speed, but my Apple //e had a full megabyte of RAM (in addition to the 64 on the motherboard) and, IIRC, Apple’s bank switching scheme could accommodate up to 16 megs. The chip would be mostly SRAM.

Talking to anything outside the chip would slow things down considerably though, and using one in place of a real 6502 would be comically weird. It’d feel like a machine that spends 99.999999% of the time waiting for IO.

Which, amusingly, feels the opposite of mainframes, where the machine appears to never have to wait for IO.

I think that would be approaching diminishing returns long before getting to 5GHz. If the only real requirement is "you can write a new value to any register on every cycle" then you need nowhere near that level of overshooting. 20MHz might not be enough (I only mentioned that value because there is an actual commercial product, the SuperCPU, that brought 20MHz 65816 to the C64/128), but 48 or 50MHz might fully cover that. Maybe 60MHz if you want to do other processing on lines where you have to slow down to communicate with the rest of the hardware (which requires slowing down to bus speed - even the base-level C128 could not use 2MHz mode with the VIC-IIe display enabled, as the extra 2MHz cycles stomped on the bus, making the VIC-II display what was essentially open bus).

Mine was never an exercise in practicality - it would be ridiculous to implement, and complete overkill.

OTOH, I wonder if someone would build something like this - a 6502/65816 with lots of SRAM and system-bus compatible timings - using the cheapest commercially available foundry, how much could it cost.

The first time I used an IBM PC I was so disappointed. On every aspect of the interaction my Apple II would run rings about it. Character IO via the BIOS on CGA was glacial to avoid writing to VRAM and getting snow, and an 8088 at 4.77 MHz was not nearly 4.77 times faster than the 6502 at 1 MHz - in fact, it felt slower.

It’s not that the 8088 was a horrible CPU - it was a pretty ok one - it’s just that the 6502 was a beast of a CPU.

The PC Engine's CPU is probably its strongest aspect, Hudson did a great job here. Going with a really fast 8-bit CPU makes much more sense than Nintendo's choice of going with a slow 16-bit CPU, especially when the screen is 256 pixels wide so most of the calculations a game would be doing are only 8 bits anyway. Even when you have to do 16-bit calculations, the SNES CPU still has an 8-bit data bus so it doesn't have much of an advantage over the PC Engine (all 16-bit operations take extra cycles compared to their 8-bit counterparts). In practice, fast action games like shooters play a lot more smoothly on the PC Engine than on the SNES. This problem is exacerbated by the fact that the SNES CPU provides the option of running at ~3/4 speed if the publisher didn't want to pay for faster ROMs, so a lot of games have unnecessary slowdown because the publisher wanted to save 50 cents per cartridge.

Where the PC Engine ends up weaker is in the video processor. That generation of consoles was able to do more with the video hardware than previous generations (like the NES and Master System) due to faster RAM becoming available. The PC Engine used the additional bandwidth to make it possible for the CPU to access video memory while the screen is being drawn, while the SNES kept the restriction that you can only access video memory during vblank and instead used the additional bandwidth for more background layers. Being able to access video memory all the time is definitely a useful feature, but the result is that PC Engine games often look more flat than SNES games.

As someone who owns a SNES and a TG-16, I think I disagree. The TG-16 graphics really pop compared to the SNES.

The SNES can only render 256 simultaneous colours. The TG-16 could do twice that at 512. Its video processor was also full 16-bit.

I’m not sure where you’re getting that the video was the weakness of the TG-16. At the time, that was the Turbografx’s whole claim to fame in that it was superior graphically to the SNES.

Source: Old enough to remember the commercials and bought both consoles to compare like nerds did back then

The PC Engine could theoretically do more colours on screen (though things like colour math and mid-screen palette changes do complicate that a bit...), but only had 9-bit wide palette entries compared to the SFC's 15-bit colour depth, which allowed for a lot more subtlety and richness.

That's the biggest Achilles' heel of the Genesis/MD, too. The lack of color resolution. I helped make the palette more accurate for that MD port of Super Mario Bros, and I made two palettes - one to simulate the composite PPU palette, and one to simulate the RGB PPU palette. The composite palette was closer, and what Mairtrus ended up shipping with (the RGB palette, no matter which "side" of mid-values I chose, wasn't quite right due to the lack of color bits)

Its big weakness is that they didn't realize how much multilayered backgrounds made things pop.

The sprites look really good, but the single background layer makes things look flat compared to the SNES / Genesis. Devs started working around that by updating some of the background tiles on each frame or using some of the sprites.

The SNES also could do layer blending effects. So while all of the input data could only be 256 colours, the PPU was spitting out a high colour signal after the effects were applied.

Remember that the PC Engine came out in 1987, over three years before the SFC did. That makes Nintendo's CPU decisions even more questionable, but also explains the huge gap in graphics hardware - not just more background layers, but also effects like transparency, scaling and rotation, and richer colours.

Nintendo first demonstrated the Super Famicom hardware in November 1988: https://www.chrismcovell.com/secret/SFC_1988Q4.html . If you look at the hardware specifications listed, the only thing they changed between then and when it came out in 1990 is increasing the work RAM from 8 KB to 128 KB. I imagine they sat on the console for so long because the Famicom was still selling and they wanted to take the time to develop a good library of launch titles.

I always assumed NEC designed this CPU, but it turns out Hudson Soft really did create it.

Hudson was apparently a legendary company. If you look at their Japanese Wikipedia page, it’s filled with "heroic tales" that almost sound like jokes.

https://ja.wikipedia.org/wiki/PC%E3%82%A8%E3%83%B3%E3%82%B8%...

The CPU was conceived by Hudson engineers who, despite their success in the NES business, felt they had hit the hardware's limits. Interestingly, they initially had no business plan. They were simply "chasing a dream" and supposedly had "no real intention of selling it," which led most semiconductor manufacturers to reject their pitch.

They managed to scrape together a few thousand samples, and by pure chance, NEC—a dominant PC manufacturer in Japan at the time—was looking to enter the console market. This lucky alignment of interests is what gave birth to the PC Engine.

While this story sounds reckless, it was only possible because Japan was in the midst of the real estate bubble, and capital was overflowing.

Once the bubble burst in the 90s, Japan entered a long recession. After a few major bank failures, Hudson’s funding dried up. They were eventually absorbed by Konami, and today, even the Hudson name is gone. It’s a real shame.

I think they tried to sell it to Nintendo at some point.

According to Wikipedia, Hudson originally approached Sharp before pitching the idea to NEC. While Sharp was enthusiastic and agreed that it had great commercial potential, the deal ultimately fell through.

The deal-breaker was Sharp’s deep relationship with Nintendo at the time. Apparently, developing a console with Hudson’s CPU was seen as something that would have jeopardized their partnership with Nintendo.

What Sharp was working on back then was the "C1 NES TV"—basically a NES-integrated television. You could think of it as the NES era's version of the iMac. It has a bit of a comical look that always makes me smile.

https://ja.wikipedia.org/wiki/%E3%83%95%E3%82%A1%E3%83%9F%E3...

I believe Hudson did design the chipset for the Sharp X68000 though, which was a very nice machine, much better than the Amiga

The X68000 was one of those mythical machines you would catch a small hint off in European gaming magazines once in a while.

The Japanese version of that TV used an internal RGB connection with an RGB PPU, making it as clear and sharp as Nintendo's Famicom-based arcade hardware.

The US version of that TV used composite internally

I didn't grow up with the PC Engine or TurboGrafx, but I did start getting into it after I got the MiSTer.

I find that the unsuccessful [1] consoles are generally pretty bad. The 3DO and the Jaguar and CD-i are mostly pretty crappy, and while it can be fun to play for a novelty and you might even find one or two games that make it worth it, the vast majority of the time there's a reason that people don't seriously revisit these consoles. To be clear, I did grow up with a 3DO and Jaguar (well, I got both when I was thirteen), so I'm not speaking out of my ass here.

So I was actually very surprised that the TurboGrafx games were actually quite good. Like, I kept going through random games, and I was shocked to find that a lot of them were actually very well made; decent graphics, tight controls, and fun gameplay.

There are terrible games on there, but I was kind of shocked to find that they appear to be outliers.

Now I kind of wish I had grown up with the Turbografx.

[1] A relative term, I acknowledge

Tons of the games were simple shmups, so I can understand people who might have the wrong idea about the library. Also, the library in Japan was way more impressive than what made it to the west. Gekisha Boy in particular still stands out as a fun and unique game (though you can play a translated version on your Mister). Fire Pro 3 is an incredible wrestling game that I still play today (no japanese required). There was another game, Zero4 Champ, which had unique drag racing gameplay (it was all about timing your gear shifts). It was hard to play without japanese knowledge, except for the 2 player head to head races. For CD games, of course, Castlevania: Rondo of Blood is well known.

I actually really liked Jackie Chan's Action Kung Fu. The NES version is pretty ok too, but I think the TurboGrafx version is a bit better. There's also the Bonk games, Air Zonk, Alien Crush, and Legendary Axe: all pretty fun games with good art style and decent controls.

Rondo of Blood was actually the only PC-Engine game I had actually played before the MiSTer, and of course it's a classic for a reason, it's great.

Something I find charming in how utterly incompetent it is is the Addams Family game on the CD. I have no idea how the hell it was even released, let alone made, because it is absurdly bad. You play as the lawyer from the movie (the absolute least interesting character in the movie) and apparently all the Addams' want you actively fucking dead. It's so unbelievably terrible that I sort of got obsessed with it and managed to actually beat it.

The Jaguar catalog was mostly meh, but there were a few gems that I really enjoyed (Aliens vs Predator, Doom, Wolf 3d, Iron Soldier, and Tempest 2000). AvP alone was worth the price of the system.

I was a proud Turbo DUO owner. It had some fantastic multiplayer games, especially 5-player Bomberman. That got a lot of play, including tournaments at work. Dungeon Explorer is another one we played through multiple times.

FYI, Sega Saturn has 10 player bomberman. It's insanely fun.

I have to push back on that a bit.

I played through the campaign for Alien vs Predator for both the Space Marine and the Alien campaigns in BigPEmu, and I really think it's a mediocre-at-best Wolf 3D clone. If it had been released on anything besides the Jag, then I think it would be, at best, relegated to the annals of mediocrity like the dozens of other Wolfenstein 3D knock offs. I wanted to like it because I love the first two Alien movies, but I really do not think it holds up compared to most FPS games, even at the time.

I haven't fully gone through the Turbo CD catalog yet, but I did play through It Came From Outer space and that was a blast in a "so bad it's good" kind of way.

I always thought the 3DO was good hardware, for 1993, let down by a high price (especially by 1993 standards) and a poor library of games: there just wasn’t a good incentive to buy the thing.

Fast forward a couple of years and the PlayStation and Saturn are both out, more technically capable, cheaper, and with better game libraries.

However, I really do think the main thing that killed the 3DO was the price - it was wildly and ridiculously expensive compared with the alternatives - and the lack of games sort of followed naturally from that because who’s going to develop for a console hardly anyone bought?

The inter-generation timing of its launch probably didn’t help. Who’s forking over when you know Sega, Nintendo and - it turns out - Sony are all going to release something better in a year or two?

I agree; if the console had been half the price it might have faired better.

Another issue is that pretty much every good game on there came out on other platforms, and often the other platform's version was actually better anyway. Return Fire, for example: great game, a lot of fun, but the PlayStation version is better in pretty much every way. Same with Road Rash, or The Horde (in a cheesy way, on the Saturn), Alone in the Dark (on the PC), etc. Despite being called the 3DO, it pretty much always had the absolute worst version of 3D games.

There are a few exclusives, and even a couple that are ok, but certainly not enough to justify the price tag. Even compared to the Saturn (a system that also tends to have pretty mediocre 3D experiences), it's pretty obvious that the 3DO is a bad deal.

> the main thing that killed the 3DO was the price

I believe this was because 3DO didn't make the consoles themselves, they licensed the design to others who made it. The console had to be profitable, rather than be sold at a loss and be subsidized by game sales.

I always wondered if the better approach would have been to have the 3DO company subsidize the development of the consoles in relation to how many games were sold, and maybe in relation to how many of those specific consoles were sold. e.g. if they dedicated half the licensing proceeds to paying back the consoles, and 80% of the 3DO consoles sold were Panasonic, than they'd give 40% of the licensing fees back to Panasonic.

I'm sure there are issues with this kind of scheme, but I think it's possible that by doing that it could have brought the console price down.

What was the story for the manufacturers though?

Why would you get into the 3DO business knowing that if it took off, you'd end up competing with other, potentially cheaper brands?

I guess the expectation was that it would be like CD players and VCRs, the market would be big enough to maintain a bunch of different brands.

I think they were going for the lattermost point. The name 3DO was kind of a pun: Audio, Video, 3DO.

I wouldn't call the PC Engine unsuccessful. Sure it did poorly in the US, but it did well in Japan, even outsold the Mega Drive (Genesis). That's definitely part of the reason it had quite a few good games by Japanese companies.

Yeah, that's why I specified that it's relative. I honestly hadn't even heard of the Turbografx until I was a teenager, but I had a Sega Genesis and Super Nintendo.

It's a real tragedy for North American gamers because it seems like we were robbed of a lot of truly amazing games for the PC Engine/TurboGrafx due to mistakes on the business side of things.

The PC Engine, released in 1987, was an incredible success in Japan, rivalling the Famicom, as its graphical effects blew the socks off Famicom players. I imagine it would have done the same in North America if it had released in 1987 or 1988 but sadly it somehow took until late August 1989 for it to be released! Years late!!!! By this point the NES was firmly established and the same month, the truly 16 bit Genesis would be released. Turbografx didn't stand a chance.

Maybe they should have sold the TurboGrafx-16 in the US only with the CD add-on already built in, and one or two CD games included to set off the hardware price somewhat. That would have made them stand out versus SNES/Genesis.

CD drives were still expensive and a bit flakey at that point. It might have worked by packing in extra games.

Sega of America was just really good at understanding the US market.

Sega did a US launch (August 29, 1989) of the Genesis 9 months after the JP launch. They had EA releasing sports games on the console in 1990.

The TG-16 came out in 1987 in JP but they waited 1 year 10 months to do a US release, so it came out after the Genesis. They didn't get any US developers on board.

A 1988 release of the TG-16 combined with some decent sports games probably would have been a success.

It was actually a big success in Japan. NEC America completely botched everything in the US market.

In Japan it came out in 1987, two years before the Sega Genesis. In the US it launched a few weeks after the Genesis. The pack in game was based on an anime that didn't come out in the US.

It's big weakness was probably that putting button batteries on HuCards was awkward, so it didn't really have many longer slower paced games with save systems.

I restored a PC Engine a year or two ago and I also became fascinated by the hardware. The HuC6270 VDC/HuC6260 VCE graphics system is actually very flexible for the kinds of games the system was designed to play. If I remember correctly, it has background tilemaps, sprites, scrolling, 64kb video RAM, and a 512 colour palette. The hardware sprites/scrolling is what makes it feel more arcadey a lot of the time.

Given the 8-bit CPU it feels a lot more like a 16-bit system to me. The dedicated sprites/scrolling hardware instead of a more bitmap/framebuffer focused design meant things like shooters and platform games played amazingly well.

Soldier Blade, R-Type, Air Zonk, Bonk, etc felt amazing. Given the formfactor and the cool card cartridge format I can see why it was so popular in Japan.

These sorts of things - sprites and scrolling tilemaps - were pretty standard for consoles of the time. C.f. the NES, Master System, Game Boy...

OTOH if you're European, my impression is that micros were more popular in the 80s and early 90s than dedicated game consoles, and I guess those tended to lack robust sprite/scrolling support, and tended to be more frame buffer-y.

Amiga 500 was very popular in Europe which had those things. Framebuffer was definitely true for the Atari ST.

No tilemaps on the Amiga.

It seems to me like there's a pattern with it in regards to differences between Japanese systems and those from everywhere else. Most Japanese arcade games in the early 1980s borrowed heavily from Galaxian's model of tilemap+sprites which pretty much became the standard. But a lot of American games (e.g. Williams' Defender, Robotron, etc. and Taito America's Qix, Zookeeper..) used a big framebuffer & blitter. Maybe memory was more expensive in Japan.

Still own multiple TG-16’s. The CD-ROM attachment plus Ys: Book I & II was a modern technical marvel at the time.

Hearing full hi-fi stereo anime rock and roll instead of chip tunes blew my mind back in the day.

Many TG CD-Games had their code in track one, and the other tracks were just redbook audio. So you pop the CD into a regular player, skip the first one or two tracks so your speakers don't blow out with static, and then enjoy the game soundtrack.

Actually, I think most had the code in track 2. Track 1 was an audio track warning you that the disc is only designed to a play on the system. More details at https://retrocomputing.stackexchange.com/questions/27518/did...

Yes, this is correct. When you put the CD into a regular player, a strikingly beautiful (but monotonous) woman’s voice would say:

“This CD is made for the Turbografx game system. Please place it into the CD drive on your Turbografx to play.”

My brother and I thought this was really cool when we were kids. We thought the CD player must “know” that it’s a game.

Diehard Gamefan was a magazine that gushed over the console’s engineering and its releases quite frequently while mainstream rags barely mentioned it. I could never afford it, even the handheld was eye-bulging expensive, but I could at least experience it vicariously, poring over the screenshots, amazed at the gorgeous sprites and artwork. Now that I can run it on emulators I fully understand the hype.

Ah, I thought the URL sounded familiar. This is the dev of the new-on-the-scene but quite good jgenesis emulator. It started out doing just Sega systems, but has started branching out, sounds like the PCE is next.

I once read that PC-Engine almost used the Motorola 68000. I'm a nerd so I bookmarked the reference.

https://archive.org/details/beep198807/page/n45/mode/2up

"According to Mr. Nakamoto of Hudson, during the development of the PC engine, he also made a prototype of an experimental machine and a game using that 68000."

Wow I haven’t thought about this console since the early 90s. It definitely did have good graphics.

Better go schedule that prostate exam

There's a youtube channel that is documenting the entire japanese PC Engine game library: https://www.youtube.com/playlist?list=PL1sb8k4ZPagYwRxx-s3mr...

They previously did the entire famicon library.

Since I missed this era of consoles, it took me a little bit to realize this wasn't about PC Engines[0] router/network/embedding computing equipment

[0]https://www.pcengines.ch/index.htm

The PC Engine was such a beautiful little console. It was mind blowing to see it the first time.

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