Model T Y2K
"Model T computer" system rom Y2K patches
General
All the KC-85 clones have the same routine holding the century digits, though appearing at different addresses. A Y2K patching rule that applies the same to all machines is to just search for a certain string of bytes wherever it happens to appear, and edit.
Using the hex-editor of your choice:
Search for this sequence: 23 36 31 23 36 39Replace it with this: 23 36 32 23 36 30
TRS-80 Model 100
- 0x5A53 0x31 -> 0x32
- 0x5A56 0x39 -> 0x30
Olivetti M10, NorthAmerica
- 0x5A5B 0x31 -> 0x32
- 0x5A5E 0x39 -> 0x30
File:M10 System ROM NorthAmerica.orig.bin
File:M10 System ROM NorthAmerica.y2k.bin
Kyotronic KC-85
- 0x575E 0x31 -> 0x32
- 0x5761 0x39 -> 0x30
File:KC-85.orig.bin
File:KC-85.y2k.bin
NEC PC-8201A, PC-8300
NEC has a second place that must be edited in addition to the same rule as all the rest.
- 0x5D91 0x31 -> 0x32
- 0x5D94 0x39 -> 0x30
- 0x7E30 0x33 -> 0x31
- 0x7E31 0x38 -> 0x30
References
http://www.muppetlabs.com/~chris/model100/y2000.html
https://www.web8201.net/default.asp?content=NECY2K.asp