Midway · 1993 · 1990s
CPU: TMS34010 @ 6.25 MHz
The board that ran Mortal Kombat II and NBA Jam — two of the highest-grossing arcade games of the 1990s — on a graphics-oriented CPU that could address individual pixels as if they were memory.
The T Unit succeeded Midway's Y Unit and debuted in 1993 with Mortal Kombat II. Its defining component was the Texas Instruments TMS34010, an unusual chip that was neither a conventional CPU nor a dedicated graphics processor but a genuine hybrid: a general-purpose 32-bit processor whose instruction set could address memory at the individual bit and pixel level. For a company whose entire aesthetic was built on digitised photography of real actors — enormous bitmap sprites rather than hand-drawn art or polygons — that was exactly the right instrument. Midway's games were, computationally, moving very large quantities of pixels around very quickly, and the TMS34010 was designed for precisely that. Physically the T Unit was two boards: a large one carrying the game logic and graphics, and a smaller dedicated audio board capable of both FM synthesis via a Yamaha YM2151 and digitised sample playback through an OKI MSM6295. Mortal Kombat II went further and used Midway's DCS sound system, an ADSP2105-driven digital audio pipeline that gave the game the crisp, punchy sampled speech and bone-crunch effects that were a substantial part of its appeal. The library is short but extraordinarily lucrative. Mortal Kombat II, NBA Jam, NBA Jam Tournament Edition, later revisions of the original Mortal Kombat, plus NARC and Terminator 2. Two of those — Mortal Kombat II and NBA Jam — were among the biggest-earning arcade machines of the decade, and between them they defined Midway's house style: digitised human beings, aggressive sampled audio, and a tone pitched deliberately at teenagers rather than children.