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 24: Line 24:
If your original system rom has the part number LH535618 (most will), then you can use [[FlexROM_100]] (optionally with [[Building a REX|REX Classic]]) to install the patched ROM.
If your original system rom has the part number LH535618 (most will), then you can use [[FlexROM_100]] (optionally with [[Building a REX|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 [[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_102.M15.orig.bin]]<br>
{| class="wikitable sortable"
[[file:TANDY_Model_102.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_102.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.
Line 67: Line 95:


==NEC PC-8201A, PC-8300==
==NEC PC-8201A, PC-8300==
NEC has a second place that must be edited in addition to the same rule as all the rest.
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".<br>
 
:0x5D91 0x31 -> 0x32
:0x5D91 0x31 -> 0x32
:0x5D94 0x39 -> 0x30
:0x5D94 0x39 -> 0x30
:0x7E30 0x33 -> 0x31
:0x7E30 0x33 -> 0x30
:0x7E31 0x38 -> 0x30
:0x7E31 0x38 -> 0x30


Line 79: Line 108:
[[file:NEC_PC-8300.orig.bin]]<br>
[[file:NEC_PC-8300.orig.bin]]<br>
[[file:NEC_PC-8300.y2k.bin]]<br>
[[file:NEC_PC-8300.y2k.bin]]<br>
For PC-8300 you can use [[FlashROM_8300]] to install the patched rom.
For PC-8300 you can use [[FLASH_23C1000]] to install the patched rom.


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

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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