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 Oscilloscope. 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. Our earlier 7854 Mostek MKB36000 ROM Repairs page had details on how to update and modify the board for repairs.

The vintageTEK museum now offers a replacement ROM board. It was designed by one of our volunteers and is available on our eBay store. It replaces the original ROM board and will work with SN below and above B100000.

7854 Rom Card Instructions Aug 2026

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

The vintageTEK museum offers a replacement ROM board. It was designed by one of our volunteers and is available on our eBay store. It replaces the original ROM board and will work with SN below and above B100000.

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