[HN Gopher] How does Sonic and Knuckles' "Lock-On Technology" wo...
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How does Sonic and Knuckles' "Lock-On Technology" work? (2016)
Author : cglong
Score : 189 points
Date : 2023-07-16 01:02 UTC (22 hours ago)
(HTM) web link (retrocomputing.stackexchange.com)
(TXT) w3m dump (retrocomputing.stackexchange.com)
| dclowd9901 wrote:
| I never had a genesis but I recall thinking how cool this was at
| the time. Kind of magic, really (granted I didn't know much about
| computers in those days, but I knew it must've been hard to alter
| an already shipped game).
|
| Turns out it has a pretty simple and clever solution. Kind of
| lost that with post production shipped patches.
| gjsman-1000 wrote:
| Sometimes, I wonder if there would be a niche market for an
| indie-focused video game console with the following constraints
| - I'm just thinking out load:
|
| - 1080p maximum video output, meaning lower production and GPU
| costs
|
| - Absolutely no internet or wireless connectivity. Wired
| controllers.
|
| - Due to no wireless connectivity, all games produced are final
| from the beginning. Like the good old days.
|
| - Switch-like cartridges, but with weaker DRM that maybe
| permits just using standard SD cards. Thus console has no need
| to have an expensive built-in disc reader and only requires
| minimal internal flash.
|
| - Due to the niche market, the console manufacturer doesn't
| charge a 30% cut, and handles all manufacturing in-house, so
| nobody needs to worry about financing a production run.
|
| I think with proper marketing, and a good enough system for
| quickly porting games (maybe it's just Proton under the hood?),
| you could find an audience in collectors... and prisons where
| the lack of connectivity is a feature.
| NovaDudely wrote:
| I don't know if it would be a hit. I was convinced that Ouya
| would have been vaguely similar in that it would allow
| smaller devs into the market by having it as an alternative
| to the big three. Instead it was plagued by all manner of
| technical issues and incredibly poor handling of the whole
| project and died in next to now time.
|
| I guess there are things like the Colour Maximite 2 that
| allows for decent speed Basic interpretation.
| https://micromite.org/shop/maximites/colour-
| maximite/colour-...
| wolrah wrote:
| You've basically described a worse Steam Deck, and would
| likely have a hard time beating the price of a Steam Deck by
| enough to be worth the sacrifices.
|
| Particularly intentionally making it unable to patch games.
| It's not like cartridge or pre-internet era disc games were
| bug free, just in that era you were stuck with whatever bugs
| the game shipped with forever. Games popular enough to get
| additional production runs were often patched, but those who
| bought an early version didn't get whatever changes the new
| one brought unless they went out and purchased a new one.
| Games that didn't sell well enough, perhaps at least in part
| _because of_ the bugs they shipped with (E.T.? Superman 64?)
| never got patched.
|
| The best case scenario back then was something like Morrowind
| on Xbox, where the game was popular enough to warrant the
| expansions being ported over from PC and released as a
| compilation with an updated version of the base game that
| included a workaround for the game-breaking issue experienced
| on the original release. We still had to buy the patch, but
| at least it came along with a lot of new content so it didn't
| feel like rebuying the same game.
| endgame wrote:
| > ...but those who bought an early version didn't get
| whatever changes the new one brought unless they went out
| and purchased a new one.
|
| And for certain groups (e.g., speedrunners), this was
| incredibly important. The example I'm most familiar with is
| Metroid Prime 1, where so many tricks and sequence breaks
| are only possible in the original NSTC release.
| wolrah wrote:
| One could make an argument that having to seek out rare
| early releases to participate in the top tier of
| speedrunning is not a good thing. It's not like updates
| changing runs destroys a game's community, see the
| recently popular "Only Up" for a great example. One of
| the models used for a substantial part of the structure
| you climb was apparently not appropriately licensed and
| the updated route after it was replaced was significantly
| shorter. People kept playing, the same names stayed at
| the top of the leaderboard, the world went on.
|
| That said, this also isn't inherently a problem either.
|
| Steam has a feature to allow delivery of different
| versions of a title. It's intended mostly for test
| releases, but some games use it to allow players to
| downgrade to specific versions for mod compatibility
| (Kerbal Space Program) or to deliver a different tweaked
| version for specific use cases (Truck Simulator VR port).
| This sort of thing could be used in the same way to
| support the speedrun community.
|
| Also there are games which have restored rare bugs
| intentionally to support speedrunning. If the bug was
| unlikely to affect someone playing normally and is
| important to the speedrunning community there's no reason
| it necessarily needs to be patched.
| gjsman-1000 wrote:
| I don't know. Unlike a Steam Deck, the lack of a screen or
| battery or large internal storage helps reduce costs - and
| the appeal to collectors comes from having physical media
| with a complete game.
|
| The Steam Deck has no physical media. Xbox and PlayStation
| Physical Media is a joke with extremely buggy and often
| incomplete builds. Switch cartridges are much closer to
| ideal... but the Switch has well-known compromises.
| Performance could be far superior on a stationary non-
| handheld, you wouldn't need to develop assuming Joy-Cons...
|
| It would almost be marketable as being the machine for
| archivists and collectors; with a focus solely on what they
| appreciate (complete games, physical media, no gimmicks.)
| philistine wrote:
| There are now two disgraced video game hucksters who tried
| what you are proposing: the Coleco Chameleon and the
| Intellivision Amico.
|
| Surprisingly, the rotting corporate corpse of a company that
| is the modern Atari managed to release their version, the
| stupendously called Atari VCS. However, no one cares about
| it, with Atari's 50th anniversary collection the only thing
| of note that company has licensed. Not made. Licensed.
| jonhohle wrote:
| I'm not sure if it fits your use case but the Evercade VS is
| essentially this. Evercade carts are SD flash mapped to a
| Game Boy pin out (the first 8 pins are the same as an SD
| card). It's both easy to read carts as well as get a flash
| cart for running arbitrary ARM code.
|
| Blaze changed the way the Evercade EXP reads carts, however,
| and it seems like the console no longer reads carts, or at
| least doesn't after the first time.
| Nition wrote:
| Similarly amazing was the few games that had _additional
| controller ports_ on the cartridge. _Micro Machines 2_ is one
| example.
| EgregiousCube wrote:
| What continues to blow my mind is the Sega Channel TV
| service. So many cool things were done with carts.
| matheusmoreira wrote:
| Brazilian bank Bradesco released internet banking software
| for the Mega Drive in 1995.
|
| https://www.segaretro.org/TeleBradesco_Resid%C3%AAncia
| [deleted]
| tndata wrote:
| Cool blog post, it brings back memories!
|
| I wrote a blog post for some time ago titled "How I built my own
| Sega Mega Drive hardware dev kit from scratch"
| https://nestenius.se/2022/01/18/how-i-built-my-own-sega-mega...
| qingcharles wrote:
| That's awesome.
| Villodre wrote:
| I remember that, in order to play S3&K in emulation, you just had
| to concatenate both games in a COPY S3.BIN + S&K.BIN way (if you
| used DOS) so I mostly knew the answer already.
|
| But man, that answer in the Stack site was excellent.
| Informative, long but concise, and very fun to read.
| LeoPanthera wrote:
| Many modern Genesis emulators have the ability to select a
| second ROM to "connect" to S&K, allowing you to connect
| arbitrary carts, if you want to.
| Dylan16807 wrote:
| > If it detects Sonic the Hedgehog 2, a signal is generated on
| the ROM's D0 line, setting the Q bit of the 74HC74.
|
| This is missing some important information. One input to the flip
| flop is D0 on the ROM, yes, but it only sets when there is a
| clock signal. Otherwise there would be some _very interesting_
| coding constraints.
|
| The clock of the flip flop is connected to cartridge pin B31.
| Here's the best explanation I can find of that pin:
|
| _' /TIME' is the schematic label given to pin B31 on the
| cartridge slot. It is essentially a chip enable for the I/O port
| range $A130Fx, and is used for programming on-cart memory
| mappers. The only games I know of that use it are Beyond Oasis,
| Phantasy Star 4 (both for switching between ROM and SRAM at
| $200000-3FFFFF) and Super Street Fighter 2 (for a full-blown ROM
| banking chip). I don't know why it's called '/TIME'; perhaps they
| expected to connect an RTC chip to it._
|
| So if you write to certain addresses, the genesis will flicker
| that pin, which is great for controlling an extra chip like this.
| (I mean, it's meant to control an extra chip, but it seems like
| the plan is a significantly smarter one than a flip flop.)
| Eduard wrote:
| Great info; go ahead and add it as an answer / comment / edit
| to that Stackexchange page.
| Dylan16807 wrote:
| Well I'm not going to make my own answer to correct a couple
| sentences of someone else's answer, and I don't have enough
| points to comment or edit.
| matheusmoreira wrote:
| Hi, I'm the original author of that stack exchange answer.
| I'd be more than happy to add your information with full
| attribution.
|
| Thanks for your explanation. I'm a programmer but don't
| have a strong electronics background. Clock signals, those
| chip enable signals and how they interact were difficult
| for me, especially at the time I wrote that.
|
| Edit: I just added a full citation for your comment. Thanks
| again!
| Dylan16807 wrote:
| I don't feel like credit is necessary here but great,
| glad the info's improved.
| userbinator wrote:
| When the cartridge connector is just the CPU bus, you can put
| whatever devices you want into the address space. I'm not
| familiar with newer consoles, but I believe cartridge-based ones
| now don't do that anymore, instead treating it as a mass storage
| device interface.
| grishka wrote:
| Yes. I read somewhere that modern CPUs run so fast that various
| forms of interference become a problem if you just let the
| memory bus stick out as a slot to plug things into. Switch
| cartridges definitely use some kind of serial interface judging
| by the number of pins.
| [deleted]
| LeoPanthera wrote:
| Switch carts use an 8-bit SPI interface.
| danparsonson wrote:
| Well that's great - now I've got the music stuck in my head
| again!
|
| Seriously though, great post! As a teenager with some knowledge
| of programming I always wondered what black magic enabled them to
| graft a new character into an old game (Sonic 2) - it never
| occurred to me that they'd just shipped a new version of the game
| code.
| mdale wrote:
| Great write up. I recall the excitement of the combined effect /
| bonus games.
| matheusmoreira wrote:
| Hey, I wrote that answer seven years ago! I tried my best to
| understand and describe the circuits but I'm not particularly
| knowledgeable about electronics so I'm not sure if it's 100%
| correct.
|
| Never thought it would make it to HN. In the comments I wrote:
|
| > I wish a professional would comment on my analysis of the
| circuit; if there are errors, I would like to fix them and learn
| more.
|
| Perhaps today is the day!
| cushychicken wrote:
| Very quick read suggests you got the gist of it. (Professional
| EE with decade of embedded system HW and SW design experience
| here.)
| aerio wrote:
| This is super interesting. I had Sonic 3 (and 1 and 2) on the
| Sega Mega Drive, but it didn't come with these combining
| cartridges.
| atdrummond wrote:
| Sonic and Knuckles has the Lock-in Slot. You were one game
| away.
| [deleted]
| intellix wrote:
| Did any other game ever do this on any other console?
| NovaDudely wrote:
| Not that I am aware of. There was talk about this being a
| potential thing on N64 with Banjo and Tooie but it never came
| to be.
| atribecalledqst wrote:
| It's actually fully functional in Banjo-Kazooie, it wasn't
| until Donkey Kong 64 that Rare was told to remove it from the
| game. The game is constantly writing to a certain region of
| memory with information about which hidden locations are
| unlocked, then on the flipside when the game boots it checks
| RAM to see if the special data is there, then unlocks the
| locations. It doesn't actually work by hot swapping, it
| relies on the fact that the RAM is preserved for a certain
| amount of time after shutting the console off.
|
| I realized recently that you could actually test this -- with
| a sufficiently old N64 console, and two copies of Banjo
| Kazooie, you could use the cheat codes to unlock the hidden
| locations on one game, then swap over to the second copy.
| Theoretically, that should unlock them without having to use
| the cheat codes.
|
| If I was a bit more motivated to spend the money, I'd try it
| myself and make a Youtube video about it!
|
| Reference: https://www.raregamer.co.uk/rare-gamer-interviews-
| paul-macha...
|
| e; actually I think it's not possible for a Banjo-Kazooie
| game to transfer to another Banjo-Kazooie game, the memory
| that it writes to is different from the one it reads from.
| https://tcrf.net/Banjo-Kazooie/Stop_N_Swop
| ranger207 wrote:
| No, but there were some third-party devices like the Action
| Replay like this for cheat (read: real time manipulation of the
| data coming over the bus) purposes, which I successfully used
| to corrupt my Pokemon Diamond save file by saving in an out of
| bounds area, alas
| p1necone wrote:
| Not quite as technologically involved, but there are some disc
| based games with novel uses of disc swapping. Monster Rancher
| is a monster breeding game where you get new monsters via
| inserting any other disc into the console.
| fredoralive wrote:
| There were a couple of expansion discs for PlayStation 1
| games as well, Metal Gear Solid Special Missions and Grand
| Theft Auto: London 1969 required copies of the base games to
| operate (at least for the European / PAL releases). I suspect
| there's little data used from the original game discs except
| acting as a "key".
|
| I think the Dreamcast Pop'n'music (Japan only) games might've
| had expansion discs as well? Not sure about that one.
| Zach_the_Lizard wrote:
| I want to say Shenmue on the Dreamcast had run-of-the-mill
| multi-disc for different chapters _and_ a special disc with
| internet options.
| fredoralive wrote:
| The discs I was talking about were sold separately, not
| just multi disc games. Although Shenmue having what is
| basically a "bonus features" disc in the package is
| pretty unique (doesn't Shenmue II have some bonus stuff
| on Disc 4 as well? I think the Saturn Shenmue prototype
| video is on that disc?).
| atribecalledqst wrote:
| I know the Playstation 2 did -- Persona 3 for example, in
| Japan, had its expansion content released as a separate
| disc. (I think there was also a version released that was
| both the base game AND the expansion content)
| rahkiin wrote:
| This is basically any DLC, right? Extra code is loaded.
| LocalH wrote:
| DLC doesn't usually introduce new _code_ to a game, that
| tends to be reserved for full-on title updates. DLC is more
| like if Sonic and Knuckles could _also_ support special "new
| level" cartridges, that didn't do anything on their own, but
| when inserted on top of S&K provided new levels for the
| player, but didn't themselves contain any program code.
| doophus wrote:
| Every game I've worked on (360-era) with DLC has needed
| supporting code to be distributed in an update first.
| Everyone gets the update, then the DLC is either just an
| unlock for what's already there (but hidden), or contains
| some supporting data.
| Philadelphia wrote:
| The Game Genie for the original NES worked like that
|
| https://en.m.wikipedia.org/wiki/Game_Genie
| christoph wrote:
| Unlicensed NES Codemasters carts as well like Dizzy and Micro
| Machines, that used "plug-thru" to utilise the licence chip
| from any other official game -
| https://www.nesworld.com/codemasters.php
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