SuperGrafx
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The SuperGrafx video game console is an upgraded version of NEC's popular PC Engine system. At first it was known as the PC-Engine 2 -- which was purported to be a true 16-Bit system with improved graphics and audio capabilities, not expected to see release until 1990. However the final machine was named SuperGrafx, was released earlier than expected, in late 1989, only provided modestly enhanced graphics over the original PC-Engine, had audio that was the same as the PC-Engine and no 16-bit CPU, just the same one as the PC-Engine.
The enhancements SuperGrafx did have: Compared to the PC-Engine, SuperGrafx has four times the amount of work RAM for the main CPU, a second video chip with its own video RAM, and a priority controller chip that allowed the output of both video chips to be combined in various ways. SuperGrafx had support for 2 independantly scrolling background layers, like the Sega Megadrive/Genesis, instead of the PC-Engine's single layer.
The SuperGrafx was largely a failure due to a lack of software written to support its enhanced abilities; only 6 titles were ever released. There were no CD, SCD, or ACD games written that took advantage of the SuperGrafx platform.
In addition, its single 8-bit CPU had a heavy workload managing the extra video hardware.
Specifications
Custom Chips
Based on Hudson Soft's C62 chipset.
- HuC6280 (Enhanced 8-bit 65C02 CPU, runs @ 1.79 or 7.16 MHz, switchable by software)
- HuC6270 (Video Color Encoder)
- HuC6260 (Video Display Processor)
- HuC6202 (Video Priority Controller)
Each VDC can display a single 8x8 tiled scrollable background, and generate 64 sprites with sizes of 16x16 to 32x64 with 16 sprites visible per scanline.
The VPC divides the display into horizontal windows which can filter through either VDC display, both, or none, and control the priority between both background and sprite layers within the window. Hardly any games except for Ghouls & Ghosts made use of this unique feature.
The VPC outputs processed video data to the VCE which means both video chips had to run at the same clock speed (no mixed resolutions) and use the same 512-entry palette across all four display layers.
Memory
- 32K work RAM for HuC6280
- 64K video RAM for each HuC6260 (128K total)
The expanded work RAM is available even when the SuperGrafx has been switched into PC-Engine compatibility mode, a quirk that doesn't seem to cause any issues with original PC-Engine software.
Audio
- HuC6280 has built-in 6-channel stereo PSG, each channel can optionally be used as a CPU-driven DAC, two channels can generate noise, and one channel can frequency modulate another.
- Cartridge and EXT-BUS connector have single monaural input for mixing in an external audio source.
The addition of the CD-ROM peripheral adds CD-DA sound, and a single ADPCM channel to the existing sound capabilities of the SuperGrafx.
Input/Output
- HuCard cartridge connector.
- EXT-BUS expansion connector. (for CD-ROM, Tennokoe 2, RAU-30, etc.)
- Standard mini-DIN gamepad connector.
- Enhanced I/O port with 8 output and 4 input pins.
- 5-pin DIN A/V connector with composite video and stereo audio output only.
- Power adapter jack.
- Compatibility mode (PC-Engine or SuperGrafx) switch on back of unit.
The enhanced I/O port was designed for a multiple-input perhipheral that was shown in several game magazines but never released commercially.
Peripherals
- RAU-30 adapter Connects SuperGrafx to IFU-30 CD-ROM interface tray, as the SuperGrafx won't fit due to its unusual shape.
External links
- Magic Engine (http://www.magicengine.com) - Commercial TurboGrafx-16/PC-Engine/SuperGrafx emulator.fr:SuperGrafX