Re: Mega STe 1.44 floppy behaviour and 1772/AJAX
Posted: 16 Apr 2021 09:29
Given you have the GAL mod solder side as well, that suggests to me a pre rev B board, as the board in mine simply has a jumper for the FPU, and it came with an Ajax and 1.44MB FDD as factory fit.Pacman wrote: 15 Apr 2021 23:27I desoldered the wire and checked for continuity between the same pins -there was none, so I assume my "revision 4.1" MSTE motherboard means it's earlier than "revision B" (photo of my PCB here).rubber_jonnie wrote: 11 Apr 2021 15:12 Out of curiosity what revision mainboard do you have? If it's B or later then the jumper wire between the GAL (PAL) and the CPU isn't required according to the 1.44MB upgrade manual from Atari.
On a sidenote there's a resistor connecting two pins underneath another GAL chip to be used with a 68881 co-processor upgrade and thanks to a photo on Troed's website (the first photo showing the empty co-processor PLCC socket) I noticed the excellent idea of putting it in a socket on the other side instead (meaning no need to disassemble the entire computer in case a 68881 is to be installed). Thanks Troed!
Apart from these two "solder side modifications" I don't think there's any other need to fiddle with the solder-side again.
That difference when looking at the instructions for both upgrades suggests you have the earlier board.