Hi everyone, I've been working towards finishing off my project for increasing the speed of the Model T laptops. The idea is to create a (relatively) easy to make and install solution that allows the user to switch the clock rate from 2.5 MHz to 5 MHz. This is really nice on the 40x8 LCD machines.
The universal software command to switch clock rate is OUT 85,1 for 2x mode and OUT 85,0 for 1x mode. Of course the Model T is not designed for this, but in my experience so far, it seems reliable. I really like the upgrade and plan to install in all my laptops. Being able to operate in nominal clock mode is of course very useful because you may find some software to be incompatible. Models I have upgraded to date: * M100 (NA, early variant, not UK) * T102 * T200 * NEC PC-8201/8201a * Olivetti M10 I am publishing all the information needed to DIY this upgrade. I don't have any plans to make these upgrades. Consider this upgrade only if you are comfortable with soldering surface mount parts, and with making minor modifications to your laptop. Upgrades that are done and in the process of documentation are M100, T200, NEC. Upgrades that need a new PCB design still are T102 and M10. All information will be at this site: https://bitchin100.com/wiki/index.php?title=5MHZ_upgrade_for_Model_T I am publishing * PCB designs for the clock doubler board (there are a few variants) * schematic * bill of materials for parts you need * documentation for building the clock doubler * installation documentation per laptop Things I have discovered while developing this; 1. Power consumption goes up by about 20% when you run at 2x clock. 2. Depending on the speed of your SRAM, you may need to implement a modification to speed that up. Each model has a specific mod you need. 3. In M100 with the custom socket pinout, in most cases you need to upgrade your Main ROM to something faster. This usually involves an adapter board and an EPROM. 4. In the Tandy 200, one must slow down the machine temporarily to access the RTC. There is a specific change for that. Anyhow, as I complete a particular laptop, I'll post the needed files. Hopefully this will be of some interest for those inclined to play around with hardware. I have no problem if anyone wants to take the design and improve it or change it. Feel free to contact me directly with questions. cheers Steve
