I did some chip experimentation tonight, using Gazoo's old MiniPro. I programmed about 20 of my 49F040 chips with it, using a clamshell-type socket adapter for PLCC chips (also called a "flap" adapter). I chose the generic option for the 49F040, not the one for the PLCC variant. Every single chip burned a perfect copy on the first try.
With that I can say two things about burning these chips:
1. Always burn them as if they are the 32-pin DIP version of the chip.
2. Use a 32-pin clamshell adapter. I have bought one of these from the seller I linked to here. They are reliable, and the adapters are approximately $20, shipped. You can use cheaper adapters, but the frustration will eventually bring you to these, as I've had absolutely no problem with them, and I've burned about 100 of these chips with my adapter, in three different programmers (A TOPWIN 3000, a MiniPro TL866CS, and an Advin Pilot U84+), using operating systems from Windows 2000 to Windows 7.
As Gazoo found out, the 29F040 chips (the alternate family of 512K flash chips for the UberGROM) is a little less sensitive to the adapters--and so he preferred them to the 49F040. My testing now shows that both families will work well--even using the same programmer Gazoo did. With that, use whichever you are most comfortable with and program away, now that we know how to make both families work well in the programmers commonly used by the TI community.
Edited by Ksarul, Sat Dec 26, 2015 11:13 PM.