Fun with Programming Adapters--MBM27C4000 as an MBM27C4001

[+Ksarul]

A while back, I was able to pick up a number of MBM27C4000 chips for a good price. I was happy--until I discovered that almost no programmers support the chip. Many claim to support them, but the chips they support are not the same--as Fujitsu seems to have been on a path of their own here. What is interesting is that the MBM27C4001 is the same size (512Kx8) and uses the same programming algorithm. A lot more programmers claim to support those. I looked at the data sheets and only two pins were different, so I wired up a haywire test adapter and tried to program one on several of my programmers. Most of them still failed, as this chip is apparently uncommon enough that many of the vendors haven't thoroughly tested their ability to program them. My BK Precision 844USB is the only programmer I have successfully gotten to work, but it works perfectly once the chip ID is unchecked. I built several adapters tonight using the boards I made to make programming these chips a snap with a compatible programmer. They are robust and work exactly as desired. . . 

[+acadiel]

I’m always up for recycling and slightly re-speccing hardware like this. Especially if you can get it for a decent price. Nice job!