Retro FAQ: Sega Master System / Mark III / SG-1000 / SC-3000

Discussion in 'Retro & Arcade' started by elvis, Mar 15, 2019.

  1. elvis

    elvis Old school old fool

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    This is a partner series to our Retro Let's Play FAQ, aiming to assist people finding ways of playing old games from these old systems. All talk of resolutions, PAL vs NTSC and upscaling are covered in the Retro Display Solutions thread.

    The Sega SG-1000 was originally released by Sega exclusively for the Japanese market in 1983. After extensive arcade games that saw great commercial success, Sega needed to transition to the home market to avoid the "Video game crash of 1983", and compete directly with Nintendo's "Famicom" (i.e.: NES). Games for the unit were released both in cards (often simpler games) and cartridges (larger, more complex and more expensive games).

    Several updates to the hardware would be release. Initially a cosmetic update in the form of the Sega SG-1000 Mark II, which included detachable controller ports and a redesigned shell. A home computer variant with keyboard named the SC-3000 was made available (which shipped with Sega BASIC on a cartridge). It featured rubber keys, and would be followed by the SC-3000H with hard plastic keys.

    Finally an update to the hardware came in the form of the "Sega Mark III", which focused mainly on improved graphics. The Sega Mark III would also feature both the original PSG sound chip of the SG-1000, but offer an addon enhanced FM sound chip:
    https://segaretro.org/FM_Sound_Unit

    This console would be re-released in the west as the Sega Master System, albeit with the FM sound chip removed. The console would go on to sell particularly well in Europe, Brazil and Australia, but fail to match the might of the NES and Famicom in either the USA or Japan. To this day sales continue in Brazil with updated model hardware.

    Following the Sega Master System (and various re-packages including the "Master System Plus" with 3D glasses and light gun), the Sega Master System II was released with a different shell, and the AV ports and game card slot remove (the latter meaning 3D glasses wouldn't work natively with this system, and the only native output was terrible RF). The Master System II was designed as a lower cost, budget entry late in the unit's life, towards the market entry of the Sega Genesis / Megadrive 16 bit hardware.

    The western Master System consoles frequently included games built in to the hardware that would work even in the absence of a cartridge. These included "Hang On", "Safari Hunt", "Alex Kidd in Miracle World" and "Sonic the Hedgehog". Also included in certain first-gen Master Systems was a hidden snail maze game.

    The Master System and it's variants were a major part of the third generation of home console hardware.

    PAL vs NTSC

    Like most systems from the 8 and 16 bit era, the Master System was frame locked to regional displays. NTSC users had games running at 60Hz to match their TVs, and PAL users at 50Hz. The result being that PAL games (including graphics and music) run at 5/6th the speed of the their NTSC counterparts. Similarly the transition from NTSC's 240 progressive lines to PAL's 288 progressive lines means that games appeared vertically squashed on PAL hardware, with black borders above and below.

    While the video quality is quite poor, this offers a comparison of "Alex Kidd in Miracle World".



    Playing the original system today

    Master System hardware is still readily available second hand, although recent retro price hikes means prices are rising. The Sega Master System II is by far the most readily available, although it requires modding to utilise better video mode outputs. More discussion on that in the "Modding" section.

    Purchasing Sega Mark III units from Japan can also be a little expensive due to relative rarity compared to Nintendo hardware from the same era.

    Original 3D glasses and lightgun hardware for the Master System are becoming difficult to find and quite expensive, although the number of games they support is quite low.

    There was little region protection on Sega's 8 bit hardware, so import gaming (or western games on a Japanese console) were possible, however the consoles and cartridges had different pin counts. Simple converters can be purchased to plug one into the other easily:

    https://www.aliexpress.com/item/SMS...-Version-Adapter-SMS-Adapter/32664053050.html

    Note that FM sound is dependent on both the right console hardware, and in some cases the right region game. A list of FM compatible games can be found here:
    https://segaretro.org/FM_Sound_Unit

    My Life In Gaming have an excellent video on using your Master System, and getting the best picture from it:



    Backwards compatibility

    The Sega Megadrive and Genesis featured hardware backwards compatibility with the Sega Master System, however a convert was required. Sega sold one officially as the "Sega Power Base" which included a cart slot. Cheaper third party models are available that don't have the card slot, but allow simply connectivity of cartridges. Some games don't function through the converter, and some don't work with a Sega Megadrive controller (the list is quite short, but features games like the popular "Wonderboy in Monsterland").

    db Electronics sell a converter card that not only allows Master System games to be played on Megadrive, but also adds in FM sound support without any complex modding required:
    https://db-electronics.ca/product/power-base-fm/

    It's also worth noting that for many games, the Sega Megadrive/Genesis controller will work on a Sega Master System. "B" maps to Button I, and "C" maps to button "2". The Master System's controller was frequently disliked by people used to Nintendo's patented D-pad, so a Megadrive controller is often nicer to play on for many. Similarly, Megadrive controllers are typically easier to find either second hand or as third party clones.

    Modding, addons

    The most common mod for the Sega Master System II is to re-enable AV outputs. Modding for composite/CVBS and RGB is quite straight forward (signals can be taken direct from chip legs on the main board, and a simple resistor/capacitor combo will bring them to required coupling levels). S-Video is somewhat trickier, requiring a basic buffer circuit.

    Modding guide here:
    http://www.mmmonkey.co.uk/console/sega/sms2-av.htm

    Premade buffer circuit for S-Video here:
    https://console5.com/store/cxa1145-s-video-and-composite-video-mod-pcb.html

    A 50/60Hz mod allows to speed PAL Master System games back up to NTSC levels. However note that this requires a crystal swap for using composite/CVBS or S-Video, otherwise the image will appear black and white. If using RGB/SCART, no crystal swap is needed, and the mod is quite simple:

    50/60Hz mod:
    http://www.mmmonkey.co.uk/console/sega/sms2-5060.htm

    NTSC crystals:
    https://console5.com/store/3-579545mhz-ntsc-crystal-large.html
    https://console5.com/store/3-579545mhz-ntsc-crystal-small.html

    The original Master System used the same AV cables as a Sega Megadrive or Genesis from the same region. Ensure when buying these you match the pinout shape at the rear of your console, as they differ between PAL and NTSC consoles. These are easily available on AliExpress or eBay.

    HD RetroVision sell a special cable that converts a Megadrive or Master System's native RGB to a YPbPr Component signal (via a small circuit in the cable header). These offer excellent picture quality out to TVs that only accept component signals, and don't have RGB/SCART connectors:
    https://www.hdretrovision.com/genesis

    Third party Megadrive controllers (compatible with the SMS) are easily found on AliExpress and eBay too.

    Spare power supplies are also readily available. Always read the bottom of your console to ensure you match both voltage and amperage requirements:
    https://www.retrosales.com.au/produ...power-supply-adapter-pack-3025-ii-new-au-plug

    Mods are available to add FM sound back to Master Systems. Complexity of install depends on the model of Master System you're using:
    https://etim.net.au/smsfm/smsfm.html

    Flash carts, clone carts

    Krikzz sells an Everdrive flash cart model that allows loading of all Master System games onto an SD card, and these are easily playable directly on your hardware. These carts will allow you to play SG-1000 games on your Master System (although the colours are slightly off due to slight hardware differences).
    https://krikzz.com/store/home/51-master-everdrive.html

    For earlier SG-1000 and SC-3000 systems, there is a "Multicart", however it ships only with homebrew titles. It is possible to add more, but you need special hardware to flash the ROM chips yourself:
    http://www.sc3000-multicart.com/megacart.htm

    FPGA simulation

    Analogue's Mega Sg console features full compatibility with SG-1000, SC-3000, Mark III and Master System titles. See the OCAU thread here:
    https://forums.overclockers.com.au/threads/analogue-mega-sg.1254087/

    [March 2018 update]
    MLIG's Analogue Mega Sg guide has a substantial amount of content for Master System use throughout. (Noting that the Mega Sg saves Master System preferences separately to Genesis/Megadrive, making it an excellent tool for customising each console separately). Watch it here:



    The open source MiSTer FPGA project also has a fully functioning Master System core, and supports FM sound:
    https://forums.overclockers.com.au/...r-console-arcade-hardware-simulation.1253887/

    Emulation

    Master System emulation has been available for quite some time due to the unit's very simple design, common components, lack of in-cartridge addon chips and total lack of copy protection. Also thanks to the systems low power components and simplicity, running Master System emulation requires very little CPU power, so an old PC, mobile phone or Raspberry Pi is a perfect SMS emulator.

    Check out projects like Retro-Arch for PC desktop use:
    https://www.retroarch.com/
    https://docs.libretro.com/ (Scroll to For Users -> Core Documentation -> Sega Cores)

    Or Retro Pie for simple Raspberry Pi retro gaming:
    https://retropie.org.uk/
    https://github.com/RetroPie/RetroPie-Setup/wiki/Master-System

    SG-1000, SC-3000, Mark II and Master System software are all playable in MAME. See our guide here:
    https://forums.overclockers.com.au/threads/retro-faq-mame.1256345/

    A special note on the Sega SC-3000 and software on tape

    The Sega SC-3000 was my first computer. At the age of 6 my father helped me learn how to write Sega BASIC programs that did simple pictures, sound and animation, and sparked my love of both video games and computer systems in general.

    The Sega SC-3000 could store software on analogue cassette tape. It used a "bitstream" format to encode zeros and ones to certain frequencies, which could be written out to a tape and read back in. The bitstream bad basic XOR checks included to ensure data could be verified for correctness. These tapes could be easily replicated on home audio equipment, and more recently converted to other formats including standard PCM WAV files on a computer.

    The Sega SC-3000 survivors website came up with a method, with the help of the MAME/MESS project, to take captured PCM WAV files, read them in to a virtual SC-3000, and write them back out as a perfect square wave file. This effectively "remastered" data stored on tape, restoring poor quality analogue media back to perfect digital levels.

    I've been following this process for a while now. It's time consuming, but I have a handful of homebrew games hosted on my site. And as of MAME 0.206, these are now included and officially recognised by MAMEDev (and will soon be posted to archive.org for permanent storage, although they already scrape my site and have copies).

    You can read more about the process on my site, as well as download homebrew games to run either via an emulator (instructions included) or on a real SC-3000 if you have one (hover over the "Sega SC-3000 tape dumps" link at the top to see the games on offer):
    https://stickfreaks.com/sega-sc-3000
     
    Last edited: Mar 26, 2019
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  2. darkmenace

    darkmenace Member

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    Sega master system 2 was my first console, I still have it and it still works.

    It gave me many hours of fun. Some of the games were really good, but towards the end of its run half baked versions of games (likely due to hardware limitations), such as Mortal Kombat were very disappointing next to their Mega Drive counterparts.

    I still play the odd master system rom on my raspberry pi.

    I always wanted to upgrade to mega drive in the mid 90s, but my parents not being gamers weren’t going to pay the $299 RRP for one.
     
  3. WuZMoT

    WuZMoT Member

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    Never owned one but some of my earliest gaming memories are of this console at friends places in primary school.

    The active life cycle of this console in Brazil is particularly interesting. I recall someone here in this very forum pointing out that statistically its lifespan trumped any other competing console in any other generation of hardware based solely on the continued popularity in Brazil?
     
  4. badmofo

    badmofo Member

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    Sega boy here, I still vividly remember my brother and I going with mum to buy our SMS from Kmart circa 1990. It came with Hang On + hidden snail maze, and shortly after we got Double Dragon and Afterburner for Christmas. Afterburner not much chop but Double Dragon was awesome, particularly 2 player.

    I have a boxed SMS these days (not the original) and a 60Hz modded SMD. The SMS has sat idle since modding the SMD and getting some after market adapters to allow me to play SMS games on it - one adapter allows FM music in the games that support it. The image quality of the SMD is superior to the SMS I found, and now that I'm using a HD Retrovision cable with it I'm in Sega heaven.
     
  5. power

    power Member

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    Couple of interesting side notes, the controller of choice for modded Atari Lynx is the Master System pad due to it matching the two button layout, also the new 8bit do wireless controllers have been confirmed by people on social media as working with the system. So you can use a 2.4GHz or Bluetooth controller with the Master System now!

    This is not my system, but I am jealous!

    upload_2019-3-16_8-48-58.png
     
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  6. OP
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    elvis

    elvis Old school old fool

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    Trying to squeeze large arcade or 16 bit games onto the SMS was always a mistake. The SMS excelled at simple 8 bit games, and they were always the greatest successes.

    Psycho Fox, Shinobi, Wonderboy I/II/III, Zillion, Impossible Mission, Alex Kidd in Miracle World, Phantasy Star, Golden Axe Warrior, Fantasy Zone, California Games, Action Fighter, Donald Duck and Mickey Mouse games, etc. All of these were brilliant, and most totally unique on the Master System with it's incredible colours.

    When porting "bigger" games across, where developers succeeded was always when they just went their own way. Sonic and Mickey Mouse Castle of Illusion - both of these were totally different on Master System compared to their Megadrive counterparts, and in both cases were excellent unique games. Just trying to cram some larger 16 bit game onto the SMS's lower spec hardware would have been a disaster. Double Dragon was another where the SMS version was brilliant, and radically different to the arcade version (I actually prefer the SMS version overall, across all ports of that game).

    The NES had similar wins and failures, where arcade ports were poor when attempting to be accurate, and far better when developers just changed the games to suit the hardware. 8 bit development was always about either making new content for the machine, or finding inspiration from other systems and re-making it from scratch to fit the limited architecture. Those games always turned out the best, and there's tonnes of them worth playing even today.
     
    Last edited: Mar 16, 2019
  7. badmofo

    badmofo Member

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    Sonic 1 was better on SMS than SMD IMHO too - I've played a lot more of the SMS version I admit but I've given the SMD version a red hot go and just can't get into it.
     
  8. gdjacobs

    gdjacobs Member

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    I used to love Miracle Warriors. Even now, I can remember the music.
     
  9. Camm

    Camm Member

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    The master system has continued to remain a bane in my purchasing.

    Japanese system = Built in FM chip + Sega BASIC works, but no Everdrive support (and work arounds are hacky and break functionality \ stop the cart from working).
     
  10. OP
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    elvis

    elvis Old school old fool

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    Does this help at all? (I don't own either a Mark III or a Master Everdrives, but RetroCore has been doing hardware videos since before YouTube).

     
    Last edited: Mar 18, 2019
  11. Camm

    Camm Member

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    tl;dr - you lose functionality using slot adapters (much like using an Everdrive in a Power Base), and adapting it thru the rear has compatibility issues, this is just a cosmetic mod, but still ultimately uses a slot adapter.
     
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  12. ShaneHm2

    ShaneHm2 Member

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  13. OP
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    elvis

    elvis Old school old fool

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    For the Sega SC-3000 and SC-3000H, no PCB or special electronics needed. The SC-3000 took pure mono audio in, and did all audio to data sampling/conversions in-hardware.

    Literally anything that plays a WAV file out via standard non-amplified line levels will work. Any phone, PC, digital music player, CD player, whatever. Just connect up standard audio line out from your device to an RCA connector (only need one channel) and plug that direct into the SC-3000. A simple 3.5mm to RCA cable you can buy from anywhere will do the trick.

    At worst you have to fiddle a little with the volume levels, but once you've found a level it'll remain constant for any of the WAV files I provide on my site above, as they've all been digitally converted to 100% square wave with consistent amplitude.

    I might put a video up on my site showing a demo, if I get a chance.
     
  14. Thalyn

    Thalyn Member

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    You just need to ensure your output is at least 2v peak-to-peak and not distorting, though I'd probably try to avoid having over 5v peak-to-peak just in case. Ironically the SC-3000 itself only outputs about 0.8v peak-to-peak, meaning it can't actually directly communicate with another console, so it's clearly depending on some kind of gain being applied by the cassette player (either during recording or playback). Communication itself simply takes place at 1,200 baud - a single 1,200Hz pulse being a 0, double 2,400Hz pulse being a 1.

    Also, it's worth noting that the newer Everdrive firmwares (I think it's V9, but don't quote me on that) will allow you to run SG-1000/SC-3000 games on a MegaDrive or Game Gear. While the GPU in both is still technically compatible, the palettes don't match when using the older video modes. The result is that prior to this firmware most games would appear to be largely black, if not entirely black. The Everdrive guy/s seem to have implemented some kind of palette remapping during load.

    A small observation on these systems: their GPUs take the same basic RAM chips as a C64/C128, only in a smaller capacity (4116s vs 4164s). The temptation may be there to just switch out the chips and hook up the remaining trace to boost them up to 64KB of VRAM but, while it does work, it will result in the picture gradually distorting. I'm unsure of exactly the cause but either it's not refreshing them often enough or it's not providing suitable power.

    Pointless trivia: The SG-1000/SG-3000 is almost identical hardware to a Colecovision (sold locally as the Dick Smith Wizzard, much to its detriment). The only difference, aside from a few logic chips (and the ROMs), is the use of a Z80 in the Segas vs the MOS 6502 in the Coleco. And, if not for the different ROMs, they would actually be compatible with the original MSX.
     
  15. OP
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    elvis

    elvis Old school old fool

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    Only ROM games, not tape (.bit/.wav format) games, sadly. I'd love to load up all my SC-3000 tape games on a flash cart. It seems the SC3000-Survivors crew managed to do that:
    http://www.sc3000-multicart.com/section3.htm

    Beyond my know-how, sadly. If you've got any pointers on how to convert them over, I'd be grateful.

    Yeah, the colours are quite dark on a Master System. Back when we played Lode Runner I fired up the SG-1000 ROM on an SMS, and while it was playable, it was way too dark. And you can see that in games like F16 Fighting Falcon which got an SMS cart release, but is an SG1000/SC3000 game at heart.

    Good comparison here of the palettes between the machines:
    http://www.smspower.org/Development/Palette
     
  16. Thalyn

    Thalyn Member

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    I'd have to check with my brother on that one. He's the one with the SG-3000, after all, and has been working on making it communicate with newer systems.

    Off the top of my head... you could probably break them down into the raw code easily enough. Parse the wave looking for the single 1,200Hz and twin 2,400Hz signals to convert into binary. Then you'd need to adjust the header, footer, and checksums such that they conform to how cartridges work instead of tapes, which is where you lose me. But surely it could be done - you can, after all, convert waves of C64 tapes into disc images (though those formats are substantially better documented).
     
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  17. Thalyn

    Thalyn Member

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    OK, so I have a few details which could be used to help convert from a tape to a cartridge, but not a lot yet as I still haven't had a chance to talk to my brother. This is just from my own memory of what he's been telling me and a little bit of research.

    First thing is that these apparently use a CUTS/KCS tape setup - that's Computer Users' Tape Standard or Kansas City Standard - at 1,200 baud. That might help people figure out a little more than what I've got here.

    I was right about the 0s and 1s. A 0 is represented by a single, full 1,200Hz pulse (has to have both high and low portions), where a 1 is two full 2,400Hz pulses (2 highs, 2 lows), with square waves valid. All data is encoded in either 10-bit or 11-bit, with a leading 0 and either one or two 1s (I couldn't find concrete info here) surrounding each 8 bits (1 byte) of data. The carrier signal (lead-in and between packets) is a 1 (up to 3 seconds as the lead-in). There is also a checksum for each packet, which is simply a running total of all other data.

    Unfortunately, here's where my knowledge reaches its limit. I know that all data is transmitted in packets, but I'm unsure as to how long each of those packets is. They're naturally going to be some power of 2 (possibly 256), and will include a checksum (that may or may not be in addition to the power of 2). I also don't know whether that checksum includes the carry bit or not. Then there's also both a header (which includes the 16-character filename) and a terminator, but I don't know their exact structure.

    I also have no idea at all when it comes to the cartridge format, or what variance there may be between basic and assembler programs.

    But, hey, it's a start, right? Maybe someone can take that and run with it. I can probably get a little more info regarding the packet structure this afternoon.
     
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  18. OP
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    elvis

    elvis Old school old fool

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    Many thanks for the reply. All of what you mention there is documented - the SC-3000 Survivors website and SMSPower forums (same folks on both - is your brother a member of that team?) did a good job of documenting all that. That was the start of how MESS/MAME got tape read/write support, and how I managed to "remaster" these tape games in the first place.

    I'm quite the numpty when it comes to actually programming assembly though, so I was hoping for some moron-friendly copy/paste peek/poke code I could use to convert stuff in-emulator and generate a ROM image from that.

    There are Python/Perl scripts out there that convert a WAV to the ".bit" format (basically just the 1200/2400Hz cycles to 0s and 1s in a raw file). But then, as you said, there's the process of ROM headers and whatnot to make it work.

    Right now that's way beyond me both in understanding and time to learn. Perhaps a retirement project.
     
    Last edited: Apr 10, 2019
  19. Thalyn

    Thalyn Member

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    Ahhh, I see. Yeah, that's a little beyond me as well. Given enough time I could probably knock something up, but it'd be outside of the emulator and based on Pascal - as in Borland Turbo Pascal 7, to give an idea of how long it's been since I've done any real programming. Though the best way would definitely be from outside the emulator, since anything inside would have to be saved as either a tape or disc.

    BTW, I was slightly mistaken. There's no terminator at all (that was evidently the Atari he was also working on) - just a header and the body itself. There's also only one packet per file, with a single-byte subtractive checksum at the end. Theoretically if you strip the header and drop the marker bits, you could convert straight from tape to cartridge; though you may need the memory location information from the header.

    My brother has provided me with the following link that he used to source all the info he's been using to communicate with it:

    http://www.smspower.org/Development/TapeFormat

    The 4 images at the top, specifically, are what he referenced.

    And, no, he's not on the team. He's just very enthusiastic about his 8-bit computers, especially when it comes to programming them.

    He's also suggested that an external compiler could be used to convert from basic into a cartridge. But that would be something that someone else would have to look into, since he's not really interested in that.
     

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