We have some  1980's oscilloscopes at the museum which used the Mostek MKB36000 ROMs which are known to deteriorate over time (e.g. FROMs - Forgetful Read Only Memories).  One is the Tektronix 7854 Oscilloscope with Digital Storage below serial number B100000. The ROM board contains four ROM sockets, a FPLA, and two EPROMs for patches (i.e. updates) to the masked ROMs.  The FPLA "traps" addresses and the EPROMs supplies the new data.

The vintageTEK museum now offers a replacement ROM board. It was designed by one of our volunteers and is available on our eBay store. The circuit board and some parts are new. Other parts are recycled from a previous use. The ROMS contain the trapped FPLA data.

Both the regular and diagnostic firmware are included, chosen by a top-accessible DIP switch. A keypad overlay for diagnostic mode is included.