5MHz Upgrade hacks

Can we speed up the Model T? Apparently!

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

Currently I have fixed 5MHz upgrade solutions for

  M100
  T102
  M100 running NSC800 CPU

I am currently working on a software switched solution where you can change between stock clock and turbo modes using a simple OUT command in BASIC.

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.

What are the tradeoffs?

When installed, your laptop will be running at 2x clock speed. However, the system clock remains unchanged.

  1.  Processor, memory, LCD, I/O. BCR are all running at 5MHz
  2.  The serial port, modem and printer ports are unchanged
  3.  Cassette port will not work correctly.  It will be 2x faster. (makes the case for a switchable solution).
  4.  5MHz draws more current, (2.5M = about 60mA, 5M = about 100mA), so shorter battery life.
      (but you are working faster!)

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.

Computer model	Version	Upgrade file
T102	Fixed 2x upgrade V1	T102 5MHz mod V1 Nov 2021.pdf
T102	Fixed 2x upgrade V1.1	T102 5MHz mod V1.1 Nov 2021.pdf

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