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May 27, 2019
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Brooklyn, NY
Hey all - I have gone down the rabbit hole of MVS conversions... and had an interesting issue with programming the split V1-V2 and P1 ROMs.

I use a ChipMax2 and for these ROMs every ST 27C160 I threw at it failed to program. I had maybe half a dozen on hand and everyone failed to burn. My Chipmax usually does blank check -> prog -> verify. I eventually figured out when I disable verify step it will "work" as in burn the chip and not error out. None of these will pass the verify step though for some reason. I never have disabled that step before and nor did I here when doing the CHA256 board ROMs.

I triple checked the ones I burned against romident for P1 and it resolved correctly and did a byte match in a hex editor on V1/V2 and everything looked perfect so I soldered these mofos and boom I have my first conversion - Iron Clad! Everything seems to work fine.

My question is are these EPROMs on their last leg or potentially gonna fail soon? Is there anything to worry about with this verify step not working? Should I order new EPROMs or is it ok if you can get a successful burn sometimes but not verify step to work?