RGB Modding the SG-1000 II! Is it value it?
The SG-1000 II is usually simply thought-about the SG-1000 in a special field. And that’s considerably true! There are not any video games unique to the SG-1000 II. No graphics modes. No sound options. However but, this variant of Sega’s first console options big modifications, and its DNA in all probability continued to echo down the Sega lineage to the Genesis. How so? And can an RGB mod all the time resolve your issues?
SG-1000
The SG-1000 was Sega’s first residence online game console. It undoubtedly isn’t a ColecoVision in a special field, however it might or might not be equivalent to the ColecoVision apart from minor port variations and lacking the ColecoVision’s copyrighted ROM. It hasn’t proven up on this weblog, however its pc cousin, the SC-3000 has.
The SG-1000 got here out on the identical day because the Nintendo Famicom. And the Nintendo Famicom destroyed it in nearly each means. Word that these are based mostly off of the 1983 specs; issues like mappers didn’t present up till later. (The SG-1000 would get some mapper-using video games too, like Loretta no Shouzou and… that’s just about it)
| Sega SG-1000 | Nintendo Famicom | Winner | |
|---|---|---|---|
| CPU | 3.5 MHz Z80 | 1.7 MHz 6502-like | Tie* |
| WRAM | 1 kiB | 2 kiB | Nintendo |
| VRAM | 16 kiB | 2 kiB + 256b OAM | Sega |
| Cartridge ROM | 32 kiB | 32 kiB | Tie |
| Cartridge RAM | 8 kiB | 2-4 kiB | Sega |
| Cartridge VROM | 0 kiB | 8 kiB | Nintendo |
| Controller buttons | 6 | 8 | Nintendo |
| Sound channels | ~3 sq. + noise | 2 sq. + noise + PSG + triangle | Nintendo |
| Decision | 256×192 | 256×224 | Nintendo |
| Shade palette | 16 colours | ~54 colours | Nintendo |
| Sprite rely | 32 | 64 | Nintendo |
| Sprites/scanline | 4 | 8 | Nintendo |
| Colours per sprite | 1 | 3 | Nintendo |
| Colours per tile | 2 per 8×1 tile** | 4 per 8×8 tile | Tie |
| {Hardware} tilemap scrolling | No | Sure | Nintendo |
* – Name me a 6502 fangirl if you want
** – Mode 2, which most video games used
Now, this isn’t fairly truthful. Many of the limitations of the Sega SG-1000 come from its Texas Devices TMS9918A video chip, designed again in 1981 for the TI-99/4A pc. Nintendo and their graphics chip designer, Ricoh, might and did be taught from its limitations and develop upon them. However Sega doesn’t get any factors for utilizing an earlier chip.
One other means the SG-1000 was dated at launch was its hardwired controller. Certain, the Nintendo Famicom had hardwired controllers too. Nevertheless it wasn’t being hardwired that was the difficulty; it was the type. The Famicom launched the patented cross-shaped D-pad and buttons that took the gaming world by storm; the SG-1000 had another button than the Atari 2600 (launched because the 2800 in Japan, for some cause) however stored the same joystick controller kind issue; very paying homage to the later Atari 7800 joystick, however with out the wedge.
That being stated, Sega did fairly properly for itself at first, with way more releases than Nintendo, who have been additionally distracted by a expensive {hardware} recall. (Early Famicoms that have been topic to the recall have square-shaped A and B buttons) However by 1984 the tide started to shift dramatically, particularly with Namco bringing on wonderful ports of its arcade hits. (Namco and Nintendo are nice associates, certainly this received’t change within the US) The SG-1000 was flagging, and a full-scale “Famicom increase” was occurring.
So what did Sega do? Acquired a brand new field to shove all of it in.
The SG-1000 II is an SG-1000 in an admittedly modern, modern-looking field. It has the identical {hardware} capabilities. It has the identical software program capabilities. They didn’t even add a card slot for the skinny “MyCard” {hardware} that may come the subsequent yr. At the least they redesigned that controller.
It’s undoubtedly much more Famicom-like. The controller is designed to have a small joystick screw into the directional circle, however I don’t actually ever see them present up in auctions, so I’m assuming the fiddly joysticks have been both shortly misplaced or by no means put in. You don’t want them anyway. Discover the buttons are unlabeled, like the unique SG-1000. The left button maps to the left button, and the appropriate to the appropriate. It is a bit annoying as SG-1000 video games often deal with the left button as the primary motion, however it was form of inevitable because of needing to stay appropriate with older {hardware}.
So what?
So the SG-1000 II is mainly an SG-1000 in a greater field, proper? Nicely, not fairly. Some SG-1000 IIs are SG-1000s in a greater field, that includes the identical actual TMS9918A video chip and the identical SN76489A sound chip. However some… transcend.
This specific SG-1000 II has neither of the chips I simply talked about. Regardless of having a fairly massive single-sided circuitboard, the main chips are closely consolidated right into a single massive VDP (Video Show Processor).
The Sega 315-5066 is a significant historic milestone. So far as I do know, that is the primary fully-integrated Sega VDP; arcade boards just like the System 1 used a mixture of helper chips and discrete logic. This VDP design, together with the built-in SN76489A clone, would go on to be expanded upon by the Sega Grasp System, and the same VDP (with the Grasp System graphics mode and the SN76489A, however no SG-1000 modes) would serve within the Genesis, ultimately evolving into the Genesis-on-a-chip seen within the remaining Genesis 3 fashions.
What’s that? You don’t care in regards to the historic significance of the chip? Nicely, possibly you’ll care about this:
The SG-1000 solely has an RF output, and the SG-1000 II is identical. Utilizing the identical adapter I used again in 1978, I attempted to get an RF output right here, however I couldn’t get something the Framemeister might learn. And what the Trinitron might see, didn’t live long… fortunately.
The TMS9918A is, just like the Famicom, a naturally composite beast. It has no higher video output (although later modles, the TMS9928A and PAL TMS9929A, together with that utilized in my PAL SC-3000, do have element functionality), and doesn’t use RGB internally so far as I do know. However right here the Sega VDP is providing us a promise of RGB video, with CSYNC. How can we resist?
Triple bypass? Nope
My unique plan was to make use of a Sega Genesis Triple Bypass board. I figured I might use the PSG enter for the audio (which is, in any case, PSG), and provides it RGB and sync. The Triple Bypass was painstakingly developed utilizing essentially the most superior strategies for the Sega Genesis, however this earlier Sega VDP needs to be superb, proper?
Nicely, it didn’t work. And I’m pretty sure it’s not the Triple Bypass’s fault; different individuals have done it with this model. I believe I will need to have both fried the amplifier, or simply obtained unhealthy luck and had a faulty one. You see, I might see the sign.
Right here’s a picture I used to be capable of seize with my oscilloscope. Bear in mind, my oscilloscope will not be superb, and may’t seize the complete element of a video sign. Don’t fear in regards to the particular voltages right here, since my setup was very ad-hoc and never reliable. However, the yellow hint is the CSYNC output, with the vertical sync pulses video. The opposite hint is the inexperienced video enter.
The sport in query is the title display screen of Okamoto Ayako no Match Play Golf, the identical recreation I performed utilizing RF above. This isn’t really an SG-1000 recreation, it’s an Othello Multivision recreation, however they’re additionally the identical console so it’s superb. In any case, the title display screen is just about fully inexperienced, as you possibly can see from this emulator screenshot.
However whereas inexperienced sign got here in, as did 5V and floor, nothing got here out of the amplifier. I might additionally inform the SG-1000 was working accurately, as a result of by wiring to a close-by testpoint labeled TP1 (see this tweet for particulars) I used to be capable of get a reasonably good composite output with out even needing an amplifier. Nicely, it’s stricken by jailbars, however these are additionally a practice in Sega consoles that began right here.
So, what’s a Nicole to do? This was final weekend, I wished to get a publish out immediately, and didn’t need to simply purchase one other Triple Bypass board in case the difficulty was one thing else. If solely I had a tool that was designed to take uncooked Sega VDP RGB indicators, and amplify them externally earlier than sending them to a SCART output…
La resolution française
That’s proper, the Sega Adapteur R.V.B., which got here with sure fashions of the Sega Grasp System bought in SECAM territories. You’ll be able to take a look at my earlier publish for the main points, however basically, this child is three easy transistor amplifiers, because the French Sega Grasp System 2 incorporates no inner video amplifier.
So I used to be capable of wire these up, getting the audio from the positioning of the RF amplifier, which I had eliminated earlier. The Adapteur RVB doesn’t really use the composite video pin, however I wired that up as properly so I might have any output I want. Greatest to be versatile.
Sadly, I didn’t have any panel-mount 8-pin DIN connectors appropriate with Sega’s bizarre U-shaped model. And yeah, superb, my SG-1000 appears fairly foolish with a tail protruding the again.
However you already know what doesn’t look foolish? Crisp, stunning RGB video.
However… that inexperienced’s a bit brilliant, isn’t? The sign is fairly sizzling (as is the Grasp System 2 with this cable), however even with some handbook adjustment of the analog/digital converter within the Framemeister, it’s this saturated in actuality.
Dare to check
However one thing’s up. Right here’s a screenshot I took from my SC-3000, of the sport Financial institution Panic. You would possibly bear in mind it from my video about using PAL video in North America.
And now right here’s the identical recreation, on the identical Framemeister, captured over composite utilizing the Sega SG-1000 II.
Discover that the colours are a bit extra vibrant; I’m undecided if that’s chalked as much as PAL/NTSC variations or not, however this to my eye appears nearer to, say, an emulator screenshot, which agrees with SMS Energy’s palette dialogue.
.jpg){kind=link}
By comparability, our RGB sign is downright comical by comparability. The sign is sizzling and the colours are hotter, rather more saturated.
That being stated, it’s nonetheless quite a bit nearer than the SMS compatibility palette I hoped to keep away from by doing all this:
So how ought to Financial institution Panic look? One possibility may be to have a look at the field itself, which incorporates a screenshot. Judging by the slight lightness on the perimeters, I believe this was a photograph of a high-quality composite or RF TV, however I might be fallacious. In fact, the field has additionally suffered almost forty years of wear and tear and tear.
Le problème monégasque
One other recreation that actually suffers from that is Monaco GP. Right here it’s in composite mode. Discover the pale blue on the perimeters of the highway.
And now let’s have a look over RGB.
Word that this isn’t the identical because the Grasp System compatibility mode, which has an excellent darker blue.
And the field is right here too, however my field for this recreation is in fairly unhealthy situation. Nonetheless, the blue has the identical greenish desaturated tinge that the composite video, and the pink is pale.
That shouldn’t be a shock. Whilst you might argue on Financial institution Panic, the textual content in Monaco GP has the slightest edge coloration; a transparent signal of NTSC artifacting if there ever was one. This screenshot was undoubtedly RF or composite; in all probability RF. It’s additionally seemingly a literal screenshot.
Conclusions?
It’s onerous to attract conclusions right here, however personally, I really feel like composite may be the way in which to go for the SG-1000 II in any case, even with the RGB mod. Some considerations would possibly embrace the Adapteur R.V.B. producing an excessively sizzling sign; it could’ve been nicer to get the Triple Bypass working. However general, this jogs my memory of the (rather more delicate) situation with the PC Engine/TurboGrafx palettes.
To substantiate this, although, I’d love to do extra exams. I’m at present ready on some PCBs to permit me to run arbitrary packages on the SG-1000; the Master Everdrive sadly doesn’t work on the older system.
An alternative choice for TMS99xx-based machines is the TMS-RGB, which solely works on TMS992x-based machines, however converts the element indicators to an RGB output. That might be a great match for my SC-3000, however I haven’t really gotten that to work but. And even then, so far as I do know, no SG-1000 cartridge-based video games have been designed for PAL territories. Maybe the TMS9928A might be tailored to work an unique SG-1000?
My suspicion in regards to the RGB indicators right here is that they have been by no means supposed for exterior consumption; observe that the Sega VDP successors on the Grasp System and Genesis would feed their RGB output right into a separate composite encoder. Right here, they’re simply check factors, not utilized by something. The separate composite sign is output by the VDP immediately. (It will be very cool if the VDP outputs S-Video, however I’ve by no means heard that)
So, with all that stated, good video output on the SG-1000 continues to elude me, a lot as market success eluded the SG-1000 II in Japan. Higher luck next time, Sega.
