On Tue, Dec 13, 2016 at 5:50 PM, Steve Hatle <sha...@nfldinet.com> wrote:
> I acquired an ADM3-A a while back from the NWA auction, and a > generous friend was able to get me the lower case ROM chip that > was "missing" from my terminal. > > I set the DIP switches and installed the ROM. When I turned on the > terminal, the whole screen was filled with "`" characters before the > host was ever started. > > When I started up the connected Sun machine, the terminal did display > both upper and lower case characters, but the "`" characters remained > and appeared to fill out each new line, and text printed out by the > machine was followed by garbage characters - like "Login:nzzzz". Typed > characters were correctly upper or lower as typed. > > I removed the ROM and cleaned the legs of the chip. I didn't clean the > socket, since I didn't have anything like DeOxit handy. I did remove and > re-insert the ROM a couple of times. > > When I removed the ROM and set the DIPs back to the original setting, > the terminal worked like normal in all upper case. Setting the DIPs to > force upper case, etc. when the ROM was in always showed the bad > behavior though the characters were upper/lower as you would expect from > the switch settings. > > TL;DR - bad and extra characters when the ROM chip is in, everything OK > when it's out. > > So, barring a bad connection to the chip while it's in the socket, it > seems like the ROM itself could be bad. I'll dig through the maint > manuals and see if I can find anything related to this behavior. In the > meantime, any ideas from the collective are welcome. > Take a look at the silk screen on the board - ISTR there's another chip that needs to be added, some simple TTL logic. I converted mine several years ago without problems - but that was with the original ROM. -- Ian S. King, MSIS, MSCS, Ph.D. Candidate The Information School <http://ischool.uw.edu> Dissertation: "Why the Conversation Mattered: Constructing a Sociotechnical Narrative Through a Design Lens Archivist, Voices From the Rwanda Tribunal <http://tribunalvoices.org> Value Sensitive Design Research Lab <http://vsdesign.org> University of Washington There is an old Vulcan saying: "Only Nixon could go to China."