SuperGrafx could not have been the PC-FX in 1989 or even 1990. that would not be possible or practical.
I didn't say the SGX was the PC-FX. I was speculating the SGX was the stripped down version of the PC Engine 2, released to buy some time/stall the competition, while work on the PC Engine 2 evolved - eventually into the PC-FX.
It's not hard to see the similarity.
The PCE is made up of: CPU(huc6280), PSGPCM unit(on the CPU die), VCE (video & color/palette generation), and a VDC(sprites/BG).
The SGX is made up of: CPU(6280). PSGPCM(on CPU die), a VCE, two VDCs, and a priority controller for the VDCs.
The PC-FX is made up of: v810 32bit RISC CPU by NEC (not hudson this time), a VCE (a newer version but still a VCE), two VDCs(nothing different than the SGX or PCE), a video priority controller (a little more complex than the SGXs), and KING ( it's own BG unit that can scale and rotate only it's own BG, not sprites or BGs from the VDCs), an iDCT for decoding MPEG frames and RLE bitmaps (RAINBOW), and two ADPCM controllers(the same as the PCE CD unit). I've also been told the SCSI interface (proprietary SCSI version) is *very* similar to the PCE CD's. It even uses the same MCU from the CD unit that the original PCE CD used (probably with updated rom though).
You can see the similarity to the SGX with its two VDCs, a VCE, and a PSG unit. The priority controller was integrated into the VCE (makes sense). The ADPCM is the same type as the PCE CD used as is the CD MCU(SCSI). KING (Hudson's chip) handled the scaling and rotation of it's
own BG layers (up to 4). The 32bit RISC CPU was available in 1990 so it that puts it in the time frame. IMO, the PC-FX was definitely doable in '90-92. Heh- besides the CPU it seems at the support chips are Hudson's.
Also notice the name progressions:
Original VCE -huc6260, FX VCE - huc6261
Original VDC -huc6270, FX KING VDC -huc6272 (huc6271 is the mpeg/bitmap layer of RAINBOW - a VDC chip).
The Huc6273 was the 3D chip for the addon card. There are no skips in the naming progression.
Does anyone have some specs/links/or scans of the PC Engine 2 articles?