Konami development tools revealed

Who worked on it?

If it helps to expand at all: it's a standard NTSC colour clock crystal, probably both because the TMS9918 can supply that clock and because those crystals were plentifully and cheaply available, and fairly close to the 4Mhz rating of the Z80. The MSX standard inserts an extra cycle into each Z80 M1 because all Z80 memory access cycles are three cycles long except the M1 cycle. M1 is "machine cycle one" — it's when the Z80 fetches the next opcode. That fetch is four cycles total but it's divided into two cycles to read the opcode, then two for DRAM refresh. If you chuck an extra wait cycle in at the start, you go from needing a memory subsystem than can respond in two cycles but only sometimes needs to, to just needing one that can respond in three cycles. So you can use cheaper RAM and/or slower intermediary logic. The Z80 announces the difference between an M1 cycle and any other cycle, so the extra logic is cheap.

...that included this article with a translated interview by Akira Yamashita/山下 章, a game journalist, with Shigeru Fukutake, manager of Konami's MSX department