Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!uunet!mcsun!cernvax!chx400!chx400!bernina!felner From: felner@nessie.cs.id.ethz.ch (Tomas Felner) Newsgroups: comp.sys.atari.st.tech Subject: ROM sockets in a Mega ST 2 Message-ID: <1991Apr29.083447.27132@bernina.ethz.ch> Date: 29 Apr 91 08:34:47 GMT Sender: news@bernina.ethz.ch (USENET News System) Organization: Swiss Federal Institute of Technology (ETH), Zurich, CH Lines: 25 Nntp-Posting-Host: nessie I want to upgrade a friend's Mega ST 2 from Blitter TOS to TOS 1.4. I have never opened a Mega ST myself before, but I know that there are motherboards for 2 ROM chips and others for 6 ROM chips (as in the old 520s). Last night I opened his machine and I found 6 28-pin ROM sockets, labelled LO-0 to LO-2 and HI-0 to HI-2. But there are only two ROMs in the sockets labelled LO-0 and HI-0 !?!? I am confused, but I proceed and put 6 27256 EPROMS with TOS 1.4 in those 6 sockets. I boot, the screen turns white, the floppy light flashes and the machine reboots and reboots and reboots ... Questions: Why are there 6 sockets if the ROMs only need 2? Or do I have both options, 2 and 6 ROM chips? If so, how do I change from one to the other? Is there a jumper somewhere? I would prefer the 6 chips solution. If I have to stick with 2 chips, which EPROM type do I need? The revision number of the motherboard is 5.0. The machine is about 2-3 years old. Tomas Felner -- Tomas Felner, Quellenstrasse 30, CH-8005 Zurich, Switzerland email: felner@nessie.cs.id.ethz.ch, felner@iiic.ethz.ch for C hackers: #include for Modula-2 programmers: FROM Standards IMPORT Disclaimer;