STE V1.5 PLUG IN 36MHz BOOSTER ( BETA production board)
Posted: Fri Jul 27, 2018 1:06 pm
The new updated version of the simple V1 32MHz STE booster. The new V1.5 booster is a highly optimised design which gives a higher speed boost over the original design.
This booster is running 36MHz with its own oscillator. So there is no need to run a wire to the 32MHz clock on the motherboard like was needed on the previous V1 design. It also remains backwards compatible for 8MHz. You can easily turn off the booster if required via a simple switch.
It is a plug-in design the no need to one solder the CPU socket. This board simply plugs into the existing socket that is pretty much it!
It does still require the DUALTOS board. Any version of the DUALTOS boards in my store work fine. New board in the image above is a updated version which uses a smaller PCB and a smaller SMT ROM socket. Some people were having height issues with the previous design, so this board is now fractionally shorter and will fit perfectly underneath the floppy drive. There is still one wire to solder between the booster and DUALTOS boards..
This booster was intended to run at 40MHz, but with a epic load of problems with various hardware tolerances ( see the story here ) I was forced to drop the speed to 36MHz simply because the current batch of CPUs I am testing do not run reliably faster than that.
A second problem manifested itself in terms of ROM access speeds. Where after a run of quickly a hour or so, the ROM start to malfunction. So I was forced to add in a single wait state into ROM access in order to prevent this problem.
Unfortunately this dropped the ROM access speed from 309% to 268%, but because the CPU is running faster at 36MHz the overall benchmarks are marginally higher than the previous 32MHz V1 booster. Integer division has gone up from 355% to 401% which is the only real boost in speed.
However, I have patched the firmware so that wait states can be disabled. It is possible some machines may run with the wait states disabled, but currently I am sceptical about this. It would literally be a fluke on hardware tolerances if this would work or not. However, if you try booster with wait states disabled, note that the problem generally can show up anywhere between 30 seconds to 2 or 3 hours time continuous running. It is also possible it may function one day and not the next down to environmental factors.
This booster runs the CPU at 36MHz constantly and only switches to 8MHz during DMA & ACIA access. As the CPU is running constant speed, it actually runs faster than the previous 8/32MHz switching concept.
To enable "fast mode" , connect pin 9 of the GAL to 0V as shown in the image below with the white wire...
For comparison the original V1 32MHz benchmarks..
Versus the new V1.5 36MHz "slow mode"...
36MHz "Fast mode"
SWITCHING TO 8MHz MODE
Connect SW pad on the booster to 0v somewhere to enable stock 8MHz mode.
INSTALLATION
Clean the header pins with a IPA wire and make sure they are clean. The booster pins go on the outside of the as before. I would suggest poking a small pin behind the pins to bend them in with slightly to make sure they are not stuck.
Place the dummy CPU into the socket..
Then booster is to be carefully inserted into the CPU socket.
The plastic spacer fits on top as shown below. The metal shielding will press down on top of this and hold the booster board in place.
The CE Pad on the the connect to the CE line on the dualtos board (required). If you're using the blue or black inboards, you must place a 68R resistor in series with the CE wire.
NOTE:
For newcomers who are not familiar with this simple booster range.. The greatest results speed gains are shown with GEM Desktop & applications.
In terms of games, 3D games will typically benefit the most due to the higher integer division percentages. Games mostly depend on ST-RAM access speeds which are not increased with this simple booster design.
Typically you will see some gains in games in general, but realistically it would only be around 10%-25% speed gains as it is almost impossible to speed up ST-RAM access without redesigning the whole motherboard Of course there are CPUs such as the 020 or 030 which have catches built on the CPU which will help with ST-RAM speeds, but at the price of compatibility. The goal of these simple boosters is of course to keep highest compatibility as possible which means super clocking the 68000 CPU.