June 27, 2026
Pixel scandal in the silicon
IBM MCGA Gate Array Reverse Engineering
Retro chip sleuthing uncovers hidden tricks and sends commenters into full conspiracy mode
TLDR: A reverse engineer uncovered hidden features in IBM’s old MCGA graphics chip, including an unexpected video-sync capability that was never clearly documented. Commenters turned the find into a mini soap opera, freaking out over the surprise feature and joking about a possible Seiko-Epson-IBM mystery connection.
A vintage IBM graphics chip just got the true-crime treatment, and the comment section is living for it. The big reveal from this painstaking reverse-engineering project is that IBM’s old low-cost display hardware had some surprise features hiding in plain sight, including a built-in way to sync with outside video signals. For retro computer fans, that was the gasp-worthy moment. One commenter basically screamed, wait, IBM had this too? because many people long assumed that kind of fancy video trick was an Amiga-only flex.
That shock quickly turned into comment-thread detective work. The juiciest theory came from people noticing that some of the chips were made by Seiko, while one of the only non-IBM machines known to use similar graphics came from Epson. And since that chip-making arm appears tied to Seiko Epson, the community instantly put on trench coats and started muttering about possible backroom deals, sub-licenses, and, yes, outright “skullduggery.” Is there proof of a grand retro-tech plot? Not exactly. Is that stopping anyone from enjoying the mystery? Absolutely not.
There was also a wholesome side to the chaos: plenty of readers were just blown away by the sheer effort of peeling apart old silicon to figure out how it really worked. So the vibe was a perfect internet cocktail: one part awe, one part nostalgia, one part conspiracy board. In other words, exactly the kind of hardware drama people adore on retro computing threads.
Key Points
- •The article reverse engineers IBM’s MCGA chipset, which consists of two main gate arrays: the 72X8300 memory controller and the 72X8205 video formatter.
- •The reverse-engineered 72X8300 sample uses a Seiko SLA6430 gate array with 4,342 basic cells on a 2 µm CMOS process with two metal layers.
- •The reverse-engineered 72X8205 sample uses a Seiko SLA6330 gate array with 3,312 basic cells, while an IBM internal-process variant could not be fully netlisted after decapping damage.
- •Reverse engineering found that MCGA can genlock to external HSYNC and VSYNC through video connector pins 11 and 12 when bit 3 of register 0x12 is set.
- •The article identifies undocumented or test-related behavior in registers 0x10, 0x20, and 0x1A, including clock selection, compatibility timing effects, manufacturing test modes, and unknown extended-mode bits.