PsychoSync

Maybe one or all roms chips have not been flashed properly. But the guy who made them for said he tested them in his machine if i remember correctly. And also, what is that big white knob for on the right side of the motherboard? It is numbered 1 to 4.

Nope. Just tried it and same ol' grey screen... I don't have any capacitors of the type required so i'll buy some this week and try soldering that this weekend i guess.

Ok i did try to swap order of chips hi-0 with hi-2 and lo-0 with lo-2 and that did not change anything so before trying to solder on capacitors i'm gonna try putting lo chips at top and hi chip at the bottom. I'll keep you posted.

Well it is working perfectly with only the 2 rom chips. I get a nice rainbow effect background and a window that tells me to insert system disk. But i don't want to load the TOS that way, i want to load it from Roms.

Hi I'm new here and also i'm new to ST computers. I recently found an Atari 520ST and external floppy drive with ac adaptors in the wild for 5$! It is in working condition, i purchased an Atari monitor locally for 5$ also. This is the first model with no RF output, only 512k of RAM, no internal floppy and only 2 of 6 rom chips inside to boot TOS from floppy. I want to install TOS 1.04 with 6 rom chips instead of booting from a floppy and using too much memory doing so. I have 6 TOS rom chips that i installed in the right position but i am only getting a grey screen. I think i may have to solder some diodes i am not sure. I found a picture of the same motherboard revision that i have with 6 chips installed and there is diodes installed where there is none on my ST. Here is the picture in question: And this is my motherboard: What modification must i do to make this work? Thanks.