- The LaST Upgrade -
PART 18 - 16MHz BOOSTER & FAST_ROM V1.5
Last updated December 7, 2015
The next generation of booster is the V1.5 version. While the V1 only boosted the CPU to 16MHz, the V1.5 also includes boosting speed to the TOS ROMs. The new board is slightly larger than the V1 and sees the removal of the TTL logic IC's in favor for a GAL. TTL logic alone was unfortunately not fast enough to work with Fast-ROM so the choice to move to a GAL was required.
In order for the ROM to work at higher speeds, the ROMs need to be replaced with a suitable "Fast-ROM" kit which I also sell in my store. 16MHz CPU generally adds around 25% speed boost to the overall speed. Running Fast-ROM gives up to a additional 30% boost to GEM/TOS related calls.
Add a blitter to your STFM/MEGA and see the figures hit lightning speeds! See the bottom of the page for results.
There is a pad called "SW" which can be connected to a switch to link the wire to 0V. When SW is left disconnected / floating, it enables 16MHz mode. When SW is connected to 0V, it forces 8MHz mode.
The above figures show in orange the speed boost over the V1 booster. In general this gives a additional boost of 25-30%. While Blitting sees 71% speed boost over a stock machine. The statistics showing average of 143% is a little tainted by the fact some results do not see a speed boost as the MHz speed is not increased any faster than the V1. The V1 booster was 25-30% faster over a stock machine, and the V1.5 is 25%-30% faster than the V1. So overall the speed increase is about 50% over a stock machine.
Fitting of the booster is very similar to the V1 with the addition of 1 extra wire.
CE line must be kept short to the booster board. The wire solders directly onto the CE 1M pad on the motherboard as shown above. This wire connects to the CE pin on the booster board.
Similar with the V1, the 16MHz line is taken from the shifter (pin 39) and connected to "S39" on the booster PCB.
Similar to the V1, the orange wire connects to the clock pin on the motherboard (or IC socket if used) which then connects to the MB pad on the booster PCB. The CPU clock pin is bent upwards to the PCB where the booster supplies the new CPU clock.
Above we have results using my modified version of Gembench (version 5). The first image above shows the CPU & ROM boost. The second image shows the same CPU & ROM boost but with the addition of a blitter.
We can see the blitter really kicks things into gear giving a wooping 302% display performance!
Also check out the video my gadgetuk on this booster HERE