The DFB1X is the exxos revised addition of the DFB1 (David's Falcon Booster MK1). It is a low cost easy to install plug-in accelerator for the Atari Falcon 030 which typically runs between 40MHz - 50MHz and uses the original PSU and fits within the Falcons case without modification. The Falcon CPU is crippled by its 16MHz speeds and its 16bit bus, while the DFB1X has 128MB of alt-ram which is accessed at the full 32bits giving a huge speed increase over a stock Falcon. The DFB1 also has a 40MHz - 50MHz FPU and 2 banks of user programmable flash ROM.

The DFB1X is a official licensed branch of the original DFB1 accelerator.

JC1 = Master clock select. Jumper open or closed will select 40MHz or 50MHz oscillator. Both CPU & FPU share the same clock. 40MHz is considered the default speed and 50MHz is the overclocking speed.
CLOSED = 40MHz
OPEN = 50MHz.

NOTE: The DFB1X is purchased as either a 40MHz or 50MHz capable board. If you purchased a 40MHz board , then the 50MHz option cannot be used.

BS1 = Flash ROM Bank Select.
OPEN = BANK 1
CLOSED = BANK 0

NOTE to program the flash you need to jumper the DISABLE jumper and use the flash tool.

J2 OPTION JUMPERS

OPTION
OPEN = 50MHz CPU (normal operation)
CLOSED = FORCES THE CPU 16MHz

ALTRAM
OPEN = ALT-RAM ENABLBED
CLOSED = ALT-RAM DISABLED

FLASH
OPEN = FLASH ENABLED
CLOSED = FLASH DISABLED

DISABLE
OPEN = ENABLE BOOSTER
CLOSED = DISABLE BOOSTER.

D1 = Lit = DFB1X is active and disabled the Falcons motherboard CPU
D2 = Speed indicator. Fast CPU is active when lit. This will vary in brightness depending on bus activity.
D3 = Coprocessor activity flag - DSP.
D4 = ALT-RAM access. This will vary in brightness depending on bus activity.
D5 = FPU & RESET. FPU access will flash the LED. It will light brightly while holding the reset button.

All LEDs will flash while programming the flash ROM.

DFB1X V1.05 May 19, 2025 - "Bodge wire edition" - See V105 modification.
DFB1X V1.04 July 6, 2023 - FPU tweak, Some bugs fixed in startup and clock switching. 8MHz mode now disables the boost in SI.CPX.
DFB1X v1.03 July 3, 2023 - FPU tweaks, should improve speed and stability at 40 & 50MHz.
DFB1X Release - June 28, 2023 - Modified LED behavior and speeded up booting to 50MHz.
DFB1X Alpha1 June 26, 2023

FLASH UTIL (FIXED) - Drag drop a OS image file onto the TTP to program the flash. Booster must be disabled to flash.

MAPROM / NVDI - Current required software for TOS404.Copy all this to your boot drive. You need to use AUTOSORT and make sure the boot order is, MAPROM,WDIALOG,NVDI.

PRGFLAGS - Sets the alt-ram loader bits on PRG files.

FPU INSTRUCTION TEST - FPU RAYTRACING - ST/TTRAM TEST - GB6 BENCHMARK

DFB1 Original sources https://github.com/dh219/DFB

MAPROM GITHUB https://github.com/agranlund/tftools (NOTE I have not got the current version of MAPROM to detect the TTram , so be warned!)

MAPROM - Some versions may not work. Please use the one listed above. MAPROM may crash when trying to enable alt-ram while the booster is in DISABLED mode. MAPROM may cause unknown compatibility problems with some software & should be used with caution. Currently there are no active maintainers for MAPROM.

You should cold boot (or power down) when changing between TOS and EMUTOS. Possible reset bug between OS changes.

NOTE: I have not tested any OS configurations outside of generic TOS404. EMUTOS remains untested and unverified at the time of typing. I also believe EMUTOS for the Falcon is very much still in development and may introduce its own issues.

FLASH UTIL sometimes crashes on verify - currently unknown why. Seems to be limited to my main test board currently.

Your Falcon PSU MUST output 5.00V minimum (5.10v - 5.20v is better) otherwise a lot of 030 CPUs will typically become unstable and crash after about 10minutes. The measurement should be done on the power output headers (J4) on the DFB1X. You can use this voltage adjuster mod if needed. Your PSU need to be recapped (**). This CPU issue should not be confused with thermal problems, but I always advise using the CPU with a heatsink anyway. Also note this problem of "voltage to low" happens whether the DFB1X is running at 40MHz or 50MHz.

(**) This assumes you are using an official Exxos re-cap kit. While there are various kits available online and you could source your own capacitors, choosing lower-quality components may lead to problems. As a result, any kit not provided by Exxos is considered unsupported.

Also note: If you have not purchased the FPU & CPU from the exxos store,then I expect you will have issues because a lot of FPUs and CPUs are not the stamped speed grade. Around 60% of FN40s will not work at 40MHz for example. Even fewer will work relaible at 50MHz (***). Some stamped RC50 CPUs will not even run reliable at 40MHz. All the chips I sell are verified as outlined in THIS article. You are on your own if you use your own parts.

(***) Please note that 50MHz FPUs do not exist and they are overclocked. While I will make every effort to verify they work at 50MHz, I cannot guarantee long term success.

The board as a whole can get very warm over time. I strong suggest some small air movement to keep the whole board cool. I currently do not have a solution for this myself and hope the community will come up with their own solutions.

BAREBONES likely need a small mod doing. See: HERE . This would cause the upper bank of the flash to become unstable when the jumper is removed.

Do not use blitter in HDDRIVER settings as blitter cannot access TTram and was reported bombs HERE.

It is important to ensure that your Falcon is in a stock configuration before attempting to use or diagnose issues. Every DFB1X is thoroughly tested before dispatch. This includes running several hours of testing with YAARTTT to verify TTram functionality, FPU tests to ensure every instruction within the FPU is functioning correctly, GB6 to confirm system stability, and DSP2SDMA to ensure it works without issues.

Setup Requirements

Before fitting the booster, it is assumed that your machine is fully operational and equipped with a reliable clock patch. Ensure you have the latest firmware version, which at the time of writing is version 104.

By default, TOS404 is flashed and ready to use. Your motherboard ROM and FPU need to be removed. Additionally, your power supply must provide at least 5.00V to ensure booster stability.The measurement should be done on the power output headers (J4) on the DFB1X. Any other add-ons, such as hard drives or drivers, should be removed during troubleshooting steps.

Trying to troubleshoot issues without following the minimum required steps as highlighted above will likely be futile and pointless, as you may be experiencing an issue that has already been fixed and documented. Using a different operating system such as EMUTOS should be avoided as its had little testing with the DFB1X. By deviating from any points mentioned, you are adding a extra layer of complexity into troubleshooting and should be avoided.

WARNING : When fitting the DFB1X, only pressed down on the connected parts of the PCB as pressing down on any other areas could bend PCB and potentially cause damage to the accelerator.

Additional Information

Please read the FAQ, Known Issues, and Firmware sections for the most updated information. Any issues outside the documented information are not known, and it is assumed that I have not been able to replicate such faults.

Note that I cannot guarantee compatibility with all software. This booster is a relatively new product and has had limited testing by the community. While software that works on a stock Falcon should theoretically work with the accelerator, there may be compatibility issues, particularly when running from TTram.

MAPROM may have compatibility issues with some software which would be currently unknown. The DFB1X can be booted without it, but its ROM operations will be significantly slower and TTram will not be enabled. You should always troubleshoot in the most minimal configuration possible to rule out any potential conflicts between hardware or software.

Q) I purchased a 40MHz unit, can I use 50MHz ?
A) Not likely with the supplied FPU & CPU. They were deemed rated for reliable 40MHz only.

Q) Can I swap the FPU & CPU to use 50MHz ?
A) Theoretically you could change them and use 50MHz. The exxos store now sells qualified CPUs and FPUs. However it is important to realise that finding parts which reliably work at those speeds is extremely difficult. Also there is a high risk of damaging the sockets. So I strongly advise that you do not attempt to change the FPU or CPU as such damages are not easily repairable!

Q) Does the CPU need cooling ?
A) I would strongly advise fitting a heatsink or even a small fan to keep the DFB1 cool overall and it will prolong CPU life etc.

Q) How does this compare to the CT60 ?
A) This is a incredibly difficult thing to answer. In a nutshell, the CT60 is faster, a lot more expensive and more problematical to install. The DFB1X is not as fast as the CT60, but its also a lot cheaper and simpler to install.

Q) Will the DFB1X work with "this or that" hardware addon or software ?
A) I'm afraid I don't know! I have a stock Falcon and that is it! Anything outside of this configuration, I'm afraid you are on your own.

Q) What is the red dot on the FPU ?
A) The red dot means I found the FPU cannot be overclocked reliably and was deemed a top speed of 40MHz.

Q) How do I update the firmware ?
A) Currently you must know how to do this already with suitable xlinix programming tools. I regret you will have to look on the Internet for guides on how to flash xlinix devices for windows / linux etc.

Q) Can I run the FPU on its own clock ?
A) While this is still technically possible, its has not been tested on the DFB1X and there is no guide currently on how to do this. Though in general there is really no point in doing this any more. 40MHz is generally the maximum speed of the FPU IC itself, and this is already a default speed on the booster. The jumper JC1 sets the CPU and FPU speed to 40MHz or 50MHz. So there is really no need for a separate oscillator. In general using a separate oscillator would just likely just cause more problems than it is worth. The FPU OSC option will likely be removed in future batches.

Q) Does the flash come preprogrammed ?
A) Bank zero is flashed with TOS404 by default. Generally you will already have this ROM on your motherboard anyway. Though the flash will run faster than the MB ROM when enabled. The second bank is free to program any other operating systems such as EMUTOS etc.

Q) Do I have to use MAPROM / NVDI etc ?
A) Yes! NVDI required because the blitter cannot access 32-bit addresses and therefore must be emulated within NVDI instead. MAPROM is needed to enable the 128MB alt-ram and do some general setup tasks for it. MAPROM also copies the operating system flash directly into the faster alt-ram for higher speeds than would otherwise be possible running from the flash chip itself.

Q) What is PRGFLAGS ?
A) PRGFLAGS (program flags) is needed to change program headers so that they use and load into alt-ram. By default any application will load into the slower ST-RAM. So we must use PRGFLAGS to tell the program to use the faster alt-ram memory.

Q) Why are some blitter graphics corrupted ?
A) You probably have not installed NVDI. It is needed to "disable" the blitter because it cannot access 32bit addresses when using alt-ram. Without NVDI the blitter will malfunction and you will get corrupted graphics. Incidentally, some blitter functions may also run fractionally slower than on a stock machine because of software emulation in NVDI and slower CPU functions. The blitting test in GB6 generally shows 83% speed for block blitting copy. Most blitter related functions are greatly speeded up with NVDI to a average of over 530% (tested with GB6).

Q) Is the DFB1 firmware compatible with the DFB1X ?
A) No! While the DFB1 firmware code base was used in the DFB1X, they are not compatible or interchangeable.

Q) What clock-patches does the DFB1 work with ?
A) Currently the DFB1X has only been tested with the exxos clock patch, V2,V3,V4 series. I cannot speculate on the outcome of any other clock patches or reliability of such.

Q) Do I need a heatsink or cooling ?
A) Short answer yes. There are compact heatsinks available in the store which should be used as a minimum. But are not fitted by default because there are potential clearance issues with the keyboard and metal shielding. Forced air via a small fan is ideal but there is no solutions to fitting one currently. 50MHz boards will run a lot hotter than the 40MHz types.

Q) What are the differences between the 40MHz and 50MHz boards ?
A) These are the differences between the FPU and CPU speeds offered in the store. As I am finding it difficult to find reliable 50MHz CPUs & FPUs, not many can be produced at that speed rating. I should also point out that 50MHz has not been tested for more than a couple of hours so cannot guarantee long-term reliability. Though these have been tested without a heatsink at all. So any long-term problems should be addressable by fitting a heatsink and adequate cooling.

Q) Can I overclock more than 50MHz ?
A) No. 50MHz I considered to already be the "cream on the cake". Finding CPUs which will generally run at 50MHz (or higher) is rather difficult because of the usual reprinting done on the CPUs. So there is no way to generally tell them apart from 25/33MHz parts. Technically a lot of them already overclocked running them at 40MHz.

Q) Can I switch flash banks via software ?
A) Unfortunately not. It would be a somewhat of a huge undertaking to adapt the hardware and software to do this. So rather than hold up development adding every little "nice thing", I decided to release things as operated as the original DFB1 project. I would suggest keeping TOS404 in the flash, and using EMUTOS.PRG if you need to switch OS.

Q) Can I disable the booster via software ?
A) Selecting 8MHz mode in SI.CPX will disable the 50MHz mode for compatibility with legacy software which runs to fast at 16MHz or above.

Q) Why was the FPU sold at 50MHz when its stamped as 40MHz?
A) 50MHz FPUs were never produced. The 50MHz rating comes from it being overclocked. It will be fully soak tested to prove it is reliable at 50MHz.

Q) Why are the barebones boards sold without sockets ? Can't you fit them ?
A) Once current stock is sold then likely all future boards will be sold without sockets fitted. This is because it has been incredibly difficult to ship items to China lately. Customs want detailed breakdown costs & relating paperwork of how much things cost, where thy were purchased from etc. Unfortunately some parts can be mixed in with other items purchased at the same time, even paperwork dating back several years. It would create a phenomenal amount of work to accurately breakdown just a few items on the off chance that customs will understand what they are reading and accept the package. The problem is, also as I end up paying shipping and tax to export sockets to China. Then when they are shipped back to me, I have to pay shipping and even more tax because I'm essentially buying back the sockets I sent them. Overall it has just become too time-consuming and costly to ship items back and forth to China for assembly.the sockets I already had purchased from China and they were custom-made, and I already paid shipping and tax on them once already. Paying tax on the same itmes 3 times is just madness. The sockets I cannot fit easily myself because of my RSI (and lack of time). The idea of the barebones boards is to make the DFB1X as cheap as possible to produce and make it more affordable to people to buy. If I start having to handle the boards and make changes, then the time & costs unfortunately will rapidly ramp up and it will not be such a good deal anymore.

Q) Do the barebones have firmware flashed?
A) Yes and no. While I have flashed firmware on some barebones boards, I cannot guarantee it is flashed and class them as not flashed. Flashed boards will have a exxos sticker on the bottom with the version flashed which is 104 at the time of typing.

Q) Can I use my own CPU / FPU?
A) I advise against this because CPU and FPU speed ratings are generally not what they say they are. You're basically using a non-verified part where I expect you will have issues in one respect or another. for example the majority of FN40 FPUs are actually 16MHz parts and will NOT run at 40MHz. See HERE for tests I do.

Q) Should I remove the motherboard ROM & FPU?
A) Yes. The Falcon's original motherboard ROM needs to be removed to prevent conflicts with the new flash ROM. Should the DFB1X be disabled, the motherboard ROM will need to be fitted. The motherboard ROM is also needed to be able to program the flash. Similarly, the motherboard FPU should be removed to prevent conflicts with the faster FPU on the DFB1X.

Q) Do I need a clock patch?
A) Yes. While some Falcons may work without a clock patch, this is considered an unsupported configuration and is generally unreliable. Troubleshooting systems that do not meet the minimum requirement of having a clock patch is not recommended and is not supported. The DFB1X has been extensively tested with the Exxos V2, V3, and V5 clock patches. Other brands or types of clock patches have not been tested or supported, so using them is entirely at your own risk.

More information may be found in the DFB WIKI.

These boards are sold "as is", un-tested and without CPU socket. It does not include the CPU or FPU. It does not have the firmware flashed. These boards are sold at a lower cost as they are not complete or tested.

The two jumpers need to be bridged as illustrated above. Pads 1&2 soldered for unbuffered CPU and FPU clock drive. Currently there has not been any requirement to use the buffered clocks and indeed that feature remains mostly untested. So the default is to solder them as illustrated above.

The Problem

The Blitter triggers both the FLASH and the motherboard ROM when accessed. This requires the motherboard ROM to be removed to avoid a conflict. However, with the DFB1X CPU, the motherboard ROM is disabled, so this is not an issue from that perspective.

The issue arises when the motherboard ROM is removed. The Falcon must boot from the ROM to program the FLASH. This can be inconvenient, as it requires disassembling the Falcon to reinstall the motherboard ROM.

The Solution

The V105 firmware outputs a control signal to the motherboard ROM to resolve this problem. When the DFB1X is disabled using the onboard jumper or an external switch, the motherboard ROM is enabled or disabled as needed. This eliminates the need to physically remove the motherboard ROM.

The Fix

After flashing the V105 firmware, a wire must be soldered as shown in the images below. Thankfully, the Falcon includes a pull-down resistor (R213) that provides access to the OE (Output Enable) pin of the motherboard ROM without requiring any track cutting.

When the DISABLE jumper is connected, OE is pulled low, enabling the motherboard ROM. The DFB1X is disabled, and the Falcon boots from the motherboard ROM, operating as a stock machine.

When the DISABLE jumper is disconnected, OE is pulled high, disabling the motherboard ROM. The Falcon then boots from the DFB1X FLASH. The Blitter has access to the FLASH without any operational compromise or conflicts between the ROM and FLASH.

EXPERIMENTAL. Discussion, test results and feedback in the forum thread HERE.

THE PROBLEM

When the DFB1X (or the original DFB1) is enabled, data transfers between the CPU and the Falcon's DSP over the DSP "host port" run a lot slower than on a stock Falcon. DSPBENCH v3 shows the host port running at roughly half to two thirds of stock speed. It isn't just the DFB1X either, the CT60/CT63 show much the same figures.

Most software doesn't care, but anything which pushes a lot of data through the DSP can suffer. Acetracker is the usual example, where it can give "CPU Overload" errors.

DSPBENCH v3.0b with the DFB1X enabled and the stock U68 GAL. Host port transfers are only around 54% to 76% of stock speed.

So what causes it?

The cause is inside the Falcon itself. When any accelerator takes over the bus, one of the Falcon's GAL chips (U68) adds an extra clock delay before it starts the DSP access. On top of that, Combel replies one cycle later in that mode. Every single host port transfer gets slowed down, and it adds up very quickly.

This was tracked down by Badwolf and pakman back in late 2025. pakman produced the modified GAL, and Badwolf got the original DFB1 up to around 85% of stock speed with it and some firmware changes. The last 15% was a mystery which never got solved.

EXPERIMENTAL SOLUTION

The fix comes in two parts, and you need both of them:

1. A replacement U68 GAL (GAL16V8) programmed with the "U68turbo" image. This removes the extra delay on DSP accesses while the DFB1X is in control of the bus. Blitter and DMA accesses keep the original timing.
2. DFB1X test firmware "1.06 DSP", which is Badwolf's DFB1 changes ported across to the DFB1X. This shortens the DFB1X's own part of the DSP access to match the new GAL.

Results

With the 1.06 DSP firmware and the U68turbo GAL, DSPBENCH v3.0b reads 99% to 102% on every host port and ST-RAM transfer test. That is stock Falcon speed, with the DFB1X enabled. Acetracker also played without giving the "CPU Overload" error.

DSPBENCH v3.0b with the DFB1X enabled, 1.06 DSP firmware and the U68turbo GAL fitted.

Keeping your Falcon original

The only change to the Falcon is swapping one GAL chip. Nothing is cut or soldered on the motherboard. Keep the original Atari U68 somewhere safe, and if you ever want the machine back to stock, just put it back in (along with the release DFB1X firmware).

Testing so far

With the DFB1X enabled, the following all work fine:

• DSPBENCH v3.0b (host port at 99% to 102% of stock speed)
• NemBench
• Acetracker (no "CPU Overload" error)
• GB6 (includes the Blitter tests)
• DMA2DSP (DMA transfers to the DSP)

Acetracker was also checked with the DFB1X disabled and the new GAL fitted, and works fine.

What still needs testing

Please report back in the forum thread if you try any of these:

• DSP demos
• Bus speeders (Nemesis, Phantom etc.), which I am unable to test myself

Downloads

• DFB1X test firmware 1.06 DSP: FIRMWARE
• U68turbo GAL image (JED): U68 JED

Test software

Both written by dml (Doug Little):

• DSPBENCH v3.0b, measures DSP function and host port transfer speeds: dspb300b.zip
• NemBench v2.2, measures CPU and RAM performance: nemb220.zip
• Download page: www.leonik.net/dml/sec_nemb.py

FAKE GAL CHIPS

The original U68 is a 12ns part (GAL16V8-12). The fix makes the DSP access go through two stages of logic inside the GAL, one after the other, so the speed of the chip matters a lot more than it did before. A slow chip effectively costs you double.

The problem is that a lot of GALs sold online are fakes. Old slow chips get the markings sanded off and get relabelled as faster parts, and there is no way to tell just by looking at them. A fake might program and verify perfectly in your programmer, then cause random crashes in the Falcon.

Sadly there is no simple way to check the real speed of a GAL at home. The differences are only a nanosecond or two, which is far too small to measure reliably even with a decent scope. So buy from a source you trust, and if you get crashes or odd behaviour after fitting the new GAL, try a different chip from a different supplier before anything else. The GAL is guilty until proven innocent.

CREDITS

• Badwolf, for finding the cause and the original DFB1 firmware changes.
• pakman, for the corrected U68 source and the U68turbo GAL.
• dml (Doug Little), for DSPBENCH and NemBench.