Sakharu Baguette has created an excellent documentary which explores the history of the PC Engine (known as the TurboGrafx-16 in North America), detailing its rise as a major rival to Nintendo in Japan and its struggle to find footing in the US 1.
Instead of bulky cartridges, games were released on HuCards (credit-card-sized chips), which were cheaper to make and futuristic for the time.
Retro48K has an excellent video diving in to the low level details of the PC engine hardware:
The PC-Engine used the 8-bit Hudson Soft HuC6280, an enhanced 65C02 derivative running at selectable 1.79 or 7.16 MHz. It added a memory management unit for bank switching, integrated timers and IRQ handling, and simple I/O functions, making it a compact but efficient control CPU for the system.
If you’re interested in learning more about the hardware architecture of the NES, we highly recommend checking out the post on Copetti.org.
The Develo box was a development kit sold to consumers allowing development of PC-Engine software via either an interface that can connect to either the MSX or PC-9801 2. It was created by Tokuma Shoten Intermedia.
From the book “The untold history of Japanese Game Developers Volume 2” we can see a photo of the Develo Box in action:
There were two books released for the plaform, one for assembly language and the other for basic, you can find out more on Develo Books
For more images of the Develo Box check out the page on Generation MSX: Tokuma Shoten Intermedia - DEVELOでべろBOX - Generation MSX
Interview with Takayuki Hirono where he explains the differences between the sound capabilities of the Famicom compared to the PC-engine: An Interview with 8ing and developers from Compile and TechnoSoft - YouTube