SG-1000:SG-1000 Model Differences
There are two SG-1000 models, and one revision within these models.
Models + Revisions
Models are arranged chronologically.
Original SG-1000 (1983-1984)
The original SG-1000 was released in Japan on July 15, 1983. It is easily distinguished by its large aluminum nameplate, red pause button and hardwired SJ-200 joystick. The top of the console is made of cream-colored plastic with a separate gray/beige piece which surrounds the cartridge port. At the rear of the console are the RF out, channel select, power input, power switch, and a 24-pin card edge connector which is the expansion port; this port was later used for the SK-1100 keyboard. The SJ-200 joystick comes out of the left-hand side of the console; the right hand side features a DB9 connector for a second controller.
Most SG-1000s have a nameplate with blue trim, but some earlier consoles have black trim instead. These are colloquially known as the "Germany" models due to the nameplate's color scheme resembling the German flag.
Internally, the SG-1000 features rather flimsy construction with the single-sided main board only being held in by the four case screws. Alarmingly, the cartridge port is not properly secured to the board and is only held on by its solder joints. Due to the board being single-sided, it does not take much for the cartridge port to develop cracked solder joints, leading to poor reliability.
The original console also saw a release in New Zealand under the Grandstand brand, being released as the "Grandstand Sega 1000". These are mostly identical to the Japanese model save for the different nameplate and the use of a TMS9929 VDP, due to the lack of a PAL variant for the TMS9918 chip. These models have a separate board which converts the 9929's component video signals into composite, which is then fed into the RF modulator.
SC-3000/SC-3000H (1983-1985)
Released alongside the SG-1000 was a budget home computer system known as the SC-3000. It includes a number of additional features such as a monitor output (which has composite video on most units and RGB on French units), printer connector, two mono 3.5 mm jacks for loading and saving data onto cassette, and an additional kilobyte of main RAM (2 KB vs. the SG-1000's 1 KB). The controller ports are located on the left-hand side with the cartridge port on the right-hand side of the computer. A rubber "chiclet" style keyboard is used, which results in a poor typing feel. However, Sega also produced the SC-3000H which had a full-travel keyboard for those who wanted a better typing experience. The SC-3000H is otherwise completely identical to the standard SC-3000. All SG-1000 games are compatible with the SC-3000.
Unlike many home computers of the era, the SC-3000 does not have a built-in BIOS or BASIC ROM. Instead, Sega offered separate BASIC cartridges, two of which also increased the main RAM (one to 16 KB, the other to 32 KB). Like an SG-1000, the SC-3000 will simply display a black screen if no cartridge is inserted. Internally, the SC-3000 is mostly similar to the SG-1000 as it also uses a single-sided PCB and does not have a reinforced cartridge slot. The fact that the cartridge slot is on its side means that care must be taken when inserting or removing cartridges. The power switch is mounted onto the outside of the bottom case and is directly soldered onto the motherboard, which slightly complicates repairs and modifications. Japanese SC-3000s use a TMS9918 VDP while PAL models use a TMS9929. PAL models also have a small daughterboard which converts the 9929's component video signals to composite.
In Japan, the SC-3000 came in three colors, black, white, and red, with black being the most common. These colors were also made available for the SC-3000H.
The SC-3000 also saw a release in several European countries (namely Finland, France and Italy) and in Australia and New Zealand. While the SC-3000 failed to gain significant traction in Japan or Europe, especially against the similar MSX standard in both markets, it did see some degree of success in Australasia and enjoyed a vibrant hobbyist scene there which is still active today.
Othello Multivision FG-1000 (1983)
Released during 1983, the Othello Multivision is an officially licensed "clone" of the SG-1000 designed by Sega themselves[1], and sold by toy and board game company Tsukuda Original. This unusual system features a built-in game of Othello and a built-in keyboard specifically made for playing that game. The Multivision also features 2 KB of RAM over the SG-1000's 1 KB and has a built-in joystick. Like the SG-1000, it has a controller port for a second player but the first player must use the built-in joystick. At the rear of the console are the RF out, channel select, power switch and AC adapter input. These are all arranged in the exact same order as the SG-1000.
All SG-1000 games are compatible on the Multivision, and in turn all Multivision cartridges are compatible with the SG-1000 and SC-3000.
Build quality is not much different than the original SG-1000, and the plastics on some examples have become very yellowed and brittle with age. Even just taking apart an original Multivision is very risky as it can cause damage to the screw bosses holding the shell together, and replacement parts for this very rare console are not available. It is therefore best left as a collector's item and to be used sparingly.
Pioneer SD-G5 (1983)
This unique variation of the SG-1000 was sold by Pioneer as an add-on for their "SEED" range of TVs, which were high-end displays meant to compete with the likes of Sony's ProFeel monitors. The SD-G5 plugs into a SEED monitor's expansion bay and is compatible with practically all SG-1000 games. Unlike any Sega hardware, the SD-G5 uses an 8-pin mini-DIN connector for its joystick, which is a Pioneer-branded version of the SJ-200. At the front of the SD-G5 is a badge advertising RGB support; presumably the SD-G5 has a TMS9928 VDP which has color difference signals that can be converted to RGB.
SD-G5 units are extremely rare, largely due to the fact that they were only designed for use with a particular set of expensive TV sets. Pioneer and Sega would collaborate again a decade later for the LaserActive, which featured a similar modular concept to Pioneer's SEED TVs.
SG-1000 II (1984-1985)
A year after the SG-1000's debut, Sega released a revised model known as the SG-1000 II, which set out to correct some of the flaws from the original system. It is primarily a cosmetic redesign with no hardware upgrades, with the expansion port and power switch being relocated to the front of the console and a controller port for player one. On the top, the cartridge port is offset to the right with a small yellow pause button below it. At the back are the RF out, channel select, controller ports and power input. The console was also bundled with new joypad controllers which snap onto the sides of the console for storage.
The SG-1000 II saw three different board revisions over its short life, though these are not readily apparent without a teardown or trained eye. Build quality was improved compared to the original console, as the main board is screwed down on each side of the cartridge port, and the cartridge port itself is reinforced onto the board with rivets.
Early SG-1000 IIs feature identical hardware to the original console, including a TMS9918 VDP and SN76489 audio chip. At some point during production, the TMS9918 was swapped with the TMS9118, a newer revision of the chip which only used two 8 KB chips for video RAM, as opposed to the eight 2 KB chips used by the 9918. Later on, both the VDP and PSG chips were replaced with a custom ASIC designed by Yamaha, the Sega 315-5066. This particular board variant is especially notable in that the 315-5066 has unused RGB and sync outputs, meaning that these consoles can be easily modified for RGB output. Despite this, the color palette used by the 315-5066 is slightly inaccurate compared to a TMS9918. This chip also only used two video RAM chips like the TMS9118.
Othello Multivision FG-2000 (1984-1985)
Around the time of the SG-1000 II's release, Tsukuda Original released a slightly revised version of the Othello Multivision, model number FG-2000. The FG-2000 version of the Multivision is largely identical but has a slight blue-gray tinge to the case and blue keys compared to the original FG-1000's red. The built-in joystick was also replaced with a D-pad of sorts. The console also came packaged with a specially branded version of the SG-1000 II's SJ-150 gamepad. Most importantly, the FG-2000 added a second controller port for the first player, in much the same way as the SG-1000 II. The SG-1000's expansion port was also added at the center rear, making it compatible with the SK-1100 keyboard.
Links
- Sega Retro page on the SG-1000
- Sega Retro page on the SG-1000 II
- Sega Retro page on the SC-3000
- Teardown of a Grandstand Sega 1000
- SMS Power thread discussing SG-1000 II revisions