5MHz Upgrade hacks: Difference between revisions

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== Photos ==
== Photos ==


'''T102 with a fixed 5MHz board'''
'''T102 with a fixed 5MHz board'''.  This board is easy to make, and the 10M crystal is on the main board.  No small SMT soldering!


[[Image:T102_fixed.jpg]]
[[Image:T102_fixed.jpg]]




'''T102 with a switchable 5MHz board'''
'''T102 with a switchable 5MHz board'''.  This board has to use a crystal on the clock board, and has small SMT soldering.  Harder to build, but has switchable clock.





Revision as of 07:05, 12 March 2022


Can we speed up the Model T? Apparently!

I have been investigating various ways to make the Model T run … faster.

Initially, I started with fixed 5MHz upgrades. These are practical if you never ever want to run at 2.5MHz. But, since 5MHz operation effectively renders the cassette port unusable, a switchable design might also be nice. Switchable means that you can control the speed from BASIC. In the M100/T102, port /Y1 is free to use. So, for switchable implementations

  Power up default is 2.5 MHz
  OUT144,0   sets to 2.5MHz
  OUT144,1   sets to 5MHz


Current Upgrades Status

Computer model Fixed 5MHz Switchable 5MHz
T102 V1.1 PCBs, instructions available Pending new PCBs
M100 V1.1 PCBs, instructions pending Pending new PCBs
M100 (UK) V1.1 PCBs, instructions pending Pending new PCBs
M100+NSC800 V1.1 PCBs, instructions pending Pending new PCBs
T200 not yet investigated not yet investigated
PC-8201 not yet investigated not yet investigated
KC-85 like M100? like M100?


As I test and more-or-less land on a reasonable upgrade process, I will post instruction files here If you have any questions, please get in touch with me at Twospruces at --the google mail service.

Also, since OSHPARK is so clumsy in dealing with PCB revisions (basically you can't remove a bad file design once shared), I've decided to just post PCB gerber files and schematics here. That way I can control issues that I find and always have the corrected files available.

What are the tradeoffs?

A fixed solution makes your laptop always run at 5MHz. A switchable solution gives you the option of standard operation or "TURBO mode".

Some of the considerations are captured below.

Item Fixed 5MHz Switchable 5MHz
Processor speed 5MHz 2.5 or 5 MHz
LCD 5MHz 2.5 or 5 MHz
I/O 5MHz 2.5 or 5 MHz
BCR 5MHz 2.5 or 5 MHz
Cassette assumed non functional functional in 2.5 MHz mode
Modem standard standard
Printer standard standard
Power consumption ~50% higher ~50% higher in 5MHz mode


The switchable solution is a nice way to go. Switch up when needed, switch down when necessary.

What about compatibility with REX#/REXCPM?

REX# and REXCPM from November 2021 are built and tested compatible with 5MHz. In fact my test station runs at 5MHz. If you have an earlier REX#/REXCPM, contact me to discuss what to do.


What do you need?

  Some hardware skills - soldering, PCB modification etc.
  a clock divider circuit board
  a small number of parts (depending on the solution)
  a 9.803 HC49 crystal

Instructions

Take a look at the instruction files below. Please don't try this if you are not confident of success! I welcome feedback and comments. Especially if you find errors or improvements.


Fixed 5MHz Upgrades

Computer model Version Upgrade file
T102 Fixed 2x upgrade V1.1 T102 5MHz mod V1.1 Nov 2021.pdf
T102 Fixed 2x upgrade V1 T102 5MHz mod V1 Nov 2021.pdf
M100 Fixed 2x upgrade V1 not ready just yet. Awaiting some PCBs -first design had bugs!

For M100 with NSC800, contact me for a solution. This would of course be a dedicated CP/M machine with REXCPM installed.


Switchable 5MHz Upgrades

Computer model Version Upgrade file
T102 Switchable 2x upgrade V1 not ready just yet. Awaiting some PCBs -first design had bugs!
M100 Switchable 2x upgrade V1 not ready just yet. Awaiting some PCBs -first design had bugs!


PCBs

Posted here so I can maintain and update the designs, are Gerber files, layout images and schematic images.

PCB Version Comments Gerbers Schematic and layout images BOM
Fixed 5MHz clock board This board has no small SMT and uses main board crystal. Easiest! V2 tbd tbd tbd
Fixed 5MHz clock board This board has no small SMT and uses main board crystal. Easiest! V1 tbd tbd tbd
Switchable 5MHz clock board, compact smaller board, more work to install V1 tbd tbd tbd
Switchable 5MHz clock board, simplified larger board, easier to install V3 tbd tbd tbd
M100 5MHz RAM/ROM adapter small SMT soldering, a challenge to build... V3 tbd tbd tbd

Photos

T102 with a fixed 5MHz board. This board is easy to make, and the 10M crystal is on the main board. No small SMT soldering!

T102 fixed.jpg


T102 with a switchable 5MHz board. This board has to use a crystal on the clock board, and has small SMT soldering. Harder to build, but has switchable clock.


T102 switchable.jpg

FAQ

As this is tried I'm sure questions and comments will arise. We can capture useful information here. Thanks.

coming soon - M100 fixed upgrade, software switchable solutions