You'll need a blank 27C256 EPROM and access to an EPROM burner capable of burning an image onto one of these chips. You'll also need a program capable of editing a binary file. (I use UltraEdit.)

Read the ROM image to a binary file on your PC. Using your binary editor of choice, change the four bytes as documented in the table below, at the address offsets shown.

Two things are accomplished with this cosmetic ROM patch. First, we're fixing the first two digits of our four-digit year as shown on the main menu. Instead of "19", we want "20". The second thing we're accomplishing is changing the year which defaults on a cold-start of the system. Instead of "83", we want "01".

Address	Old Value	New Value	Comment
5D91	0x31	0x32	"1" --> "2" First digit of the year
5D94	0x39	0x30	"9" --> "0" Second digit of the year
7E30	0x33	0x31	"3" --> "1" Second digit of cold-start default
7E31	0x38	0x30	"8" --> "0" First digit of cold-start default