Model T Y2K: Difference between revisions

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All the KC-85 clones have the same routine holding the century digits, though appearing at different addresses in different system roms.
All the KC-85 clones have the same routine holding the century digits, though appearing at different addresses in different system roms.


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.
A Y2K patching rule that applies the same to all machines is to just search for a certain string of 6 bytes wherever it happens to appear, and edit.


Using the hex-editor of your choice:
Using the hex-editor of your choice:
Line 26: Line 26:
If you have a late model without LH535618, then you can use a plain 27C256, or [[FlexROM_102]] (optionally with [[Building a REX|REX Classic]]), or [[28C256_to_27C256]].
If you have a late model without LH535618, then you can use a plain 27C256, or [[FlexROM_102]] (optionally with [[Building a REX|REX Classic]]), or [[28C256_to_27C256]].


==TANDY Model 102==
==Tandy Model 102==
US<br>
:0x5A53 0x31 -> 0x32
:0x5A53 0x31 -> 0x32
:0x5A56 0x39 -> 0x30
:0x5A56 0x39 -> 0x30


[[file:TANDY_Model_102.orig.bin]]<br>
[[file:TANDY_Model_102.us.orig.bin]]<br>
[[file:TANDY_Model_102.y2k.bin]]
[[file:TANDY_Model_102.us.y2k.bin]]
 
UK<br>
:0x5A53 0x31 -> 0x32
:0x5A56 0x39 -> 0x30
 
[[file:TANDY_Model_102.uk.orig.bin]]<br>
[[file:TANDY_Model_102.uk.y2k.bin]]


You can use a plain 27C256, or [[FlexROM_102]] (optionally with [[Building_a_REX|REX Classic]]), or [[28C256_to_27C256]] to install the patched rom.
You can use a plain 27C256, or [[FlexROM_102]] (optionally with [[Building_a_REX|REX Classic]]), or [[28C256_to_27C256]] to install the patched rom.


==TANDY Model 200==
==Tandy Model 200==
Model 200 system rom spans 2 chips, 32k at M15, and 8k at M13. Only M15 needs to be modified.
The Tandy 200 system ROM spans 3 chips, M15, M13, and M14. Only M15 needs to be modified.


:0x6DF1 0x31 -> 0x32
:0x6DF1 0x31 -> 0x32
:0x6DF3 0x39 -> 0x30
:0x6DF3 0x39 -> 0x30


[[file:TANDY_Model_200.M15.orig.bin]]<br>
{| class="wikitable sortable"
[[file:TANDY_Model_200.M15.y2k.bin]]
|+ Tandy 200 ROMs
|-
! Description !! Original !! Y2K Patched
|-
|'''M15''': First system ROM chip (32K)
|| [[File:Tandy_200.M15.orig.bin]] || [[File:Tandy_200.M15.y2k.bin]]
|-
|'''M13''': Second system ROM chip (8K)
|| [[file:Tandy_200.M13.orig.bin]]  
|rowspan="2"| not modified, included here just for completeness
|-
|'''M14''': Third system ROM chip<br/>Multiplan (32K, bank selected)
|[[file:Tandy_200.M14.orig.bin]]
|-
|All three ROMs (M15+M13+M14) in one file, for emulators
||[[file:Tandy_200.us.orig.bin]] || [[file:Tandy_200.us.y2k.bin]]
|}


[[file:TANDY_Model_200.M13.orig.bin]] (the 8k 2nd chip just for completeness)
You can use a plain 27C256, or [[28C256_to_27C256]], or [[FlexROM_200]] (optionally with [[Building_a_REX|REX Classic]]) to install the patched M15 ROM.
 
You can use a plain 27C256, or [[28C256_to_27C256]] to install the patched rom.


==Olivetti M10==
==Olivetti M10==
Line 52: Line 74:
:0x5A5B 0x31 -> 0x32
:0x5A5B 0x31 -> 0x32
:0x5A5E 0x39 -> 0x30
:0x5A5E 0x39 -> 0x30
<!-- [[File:M10_System_ROM_NorthAmerica.orig.hex]] -->[[File:M10_System_ROM_NorthAmerica.orig.bin]]<br>
[[File:M10_System_ROM_NorthAmerica.orig.bin]]<br>
<!-- [[File:M10_System_ROM_NorthAmerica.y2k.hex]] -->[[File:M10_System_ROM_NorthAmerica.y2k.bin]]
[[File:M10_System_ROM_NorthAmerica.y2k.bin]]
 
Europe:
:0x5774 0x31 -> 0x32
:0x5779 0x39 -> 0x30
[[File:M10_System_ROM_EU.orig.bin]]<br>
[[File:M10_System_ROM_EU.y2k.bin]]


You can use a plain 27C256, or [[28C256_to_27C256]] to install the patched rom.
You can use a plain 27C256, or [[28C256_to_27C256]] to install the patched rom.

Latest revision as of 08:34, 15 February 2026

"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 in different system roms.

A Y2K patching rule that applies the same to all machines is to just search for a certain string of 6 bytes wherever it happens to appear, and edit.

Using the hex-editor of your choice:

Search for this sequence: 23 36 31 23 36 39
Replace it with this: 23 36 32 23 36 30

TRS-80 Model 100

0x5A53 0x31 -> 0x32
0x5A56 0x39 -> 0x30

File:TRS-80 Model 100.orig.bin
File:TRS-80 Model 100.y2k.bin

Most Model 100's have a non-standard pinout for the system rom socket.
If your original system rom has the part number LH535618 (most will), then you can use FlexROM_100 (optionally with REX Classic) to install the patched ROM.

If you have a late model without LH535618, then you can use a plain 27C256, or FlexROM_102 (optionally with REX Classic), or 28C256_to_27C256.

Tandy Model 102

US

0x5A53 0x31 -> 0x32
0x5A56 0x39 -> 0x30

File:TANDY Model 102.us.orig.bin
File:TANDY Model 102.us.y2k.bin

UK

0x5A53 0x31 -> 0x32
0x5A56 0x39 -> 0x30

File:TANDY Model 102.uk.orig.bin
File:TANDY Model 102.uk.y2k.bin

You can use a plain 27C256, or FlexROM_102 (optionally with REX Classic), or 28C256_to_27C256 to install the patched rom.

Tandy Model 200

The Tandy 200 system ROM spans 3 chips, M15, M13, and M14. Only M15 needs to be modified.

0x6DF1 0x31 -> 0x32
0x6DF3 0x39 -> 0x30
Tandy 200 ROMs
Description Original Y2K Patched
M15: First system ROM chip (32K) File:Tandy 200.M15.orig.bin File:Tandy 200.M15.y2k.bin
M13: Second system ROM chip (8K) File:Tandy 200.M13.orig.bin not modified, included here just for completeness
M14: Third system ROM chip
Multiplan (32K, bank selected) 		File:Tandy 200.M14.orig.bin
All three ROMs (M15+M13+M14) in one file, for emulators File:Tandy 200.us.orig.bin File:Tandy 200.us.y2k.bin

You can use a plain 27C256, or 28C256_to_27C256, or FlexROM_200 (optionally with REX Classic) to install the patched M15 ROM.

Olivetti M10

North America:

0x5A5B 0x31 -> 0x32
0x5A5E 0x39 -> 0x30

File:M10 System ROM NorthAmerica.orig.bin
File:M10 System ROM NorthAmerica.y2k.bin

Europe:

0x5774 0x31 -> 0x32
0x5779 0x39 -> 0x30

File:M10 System ROM EU.orig.bin
File:M10 System ROM EU.y2k.bin

You can use a plain 27C256, or 28C256_to_27C256 to install the patched rom.

Kyotronic KC-85

0x575E 0x31 -> 0x32
0x5761 0x39 -> 0x30

File:KC-85.orig.bin
File:KC-85.y2k.bin

You can use a plain 27C256, or 28C256_to_27C256 to install the patched rom.

NEC PC-8201A, PC-8300

To change the "19" in "1983", it's the same rule for NEC as all the rest, but there is also a second place to change the "83".

0x5D91 0x31 -> 0x32
0x5D94 0x39 -> 0x30
0x7E30 0x33 -> 0x30
0x7E31 0x38 -> 0x30

File:NEC PC-8201A.orig.bin
File:NEC PC-8201A.y2k.bin
For PC-8201/PC8201A you can use a plain 27C256 or a 28C256_to_27C256 to install the patched rom.

File:NEC PC-8300.orig.bin
File:NEC PC-8300.y2k.bin
For PC-8300 you can use FLASH_23C1000 to install the patched rom.

References

http://www.muppetlabs.com/~chris/model100/y2000.html
https://www.web8201.net/default.asp?content=NECY2K.asp

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