Who knows the Backbit Pro Cartridge ?

[poulette73]

Hello,

I came across this product : store.backbit.io/product/backbit-pro/


This interface can be used on several computers : Amstrad Plus/GX4000, Apple II, Atari 2600/5200/7800, Commodore 64/128/VIC 20, Colecovision, Epoch, MSX, SEGA Master System, Sinclair ZX81, TI-99, ZX Spectrum , etc.
Just take the adapter compatible with the computer: store.backbit.io/product/backbit-pro-adapter/

From what I understand, it's roughly equivalent to a C4CPC cartridge from Gerald.

On the other hand, I find that the price is still very high at $129...

A video presentation on how it works:

[Gryzor]

Huh, that's pretty interesting. Yes it's expensive but then again if you have a collection of a certain size, having a single solution becomes pretty economical in all terms... 

[poulette73]

More informations (concerning the Amstrad Plus/GX 4000) :

• Amstrad Plus/GX4000 has a chip for ACID protection bypass.

• The following adapters include a solderless jumper (one jumper is included, and extra jumpers can be purchased): Amstrad Plus/GX4000 (required for ACID bypass).
• 3.5mm jack allows connecting a BackButton or GenAssister, allowing easy navigation back to menu interface (some systems, such as ColecoVision/Amstrad/Atari, require an included solderless jumper).
• Supports cartridge images (BIN/CPR) up to 1MB in size.
• Real-time-clock remembers date & time even after shutoff. Useful when creating new files or versions.
• One-button diagnostic mode helps you identify system faults (on most systems).
• Upgradeable via MicroSD card.

[eto]

Clever and simple design where a simple adapter makes it work with different systems. In the end, it's probably just a (Teensy?) microcontroller that behaves as ROM and can react on specific actions to load images from SF card into its RAM. 

I guess we could use a similar approach with e.g. a Teensy, a few level shifters and a NoAcid IC to come up with a community / Public Domain successor to the C4CPC. As it would not require a FPGA it would be easy to replicate for many - and some will offer it on Ebay for a few bucks more. 

[roudoudou]

clever design for people owning many different architecture

else...

very expensive!

geraaaaaaaaaaaaaaaaaald come baaaaaaaaaaaaaack

[lordheavy]

clever design for people owning many different architecture

else...

very expensive!

geraaaaaaaaaaaaaaaaaald come baaaaaaaaaaaaaack

Better, release your design under an open license - see c64's kung fu flash, an open design for the hardware and the software.

c4cpc is "just" the a cpc's kung fu flash but not freed. So now it's nearly dead, because you can't easily reproduce it without specs.

voilà !

[tzibu]

clever design for people owning many different architecture

else...

very expensive!

geraaaaaaaaaaaaaaaaaald come baaaaaaaaaaaaaack

Better, release your design under an open license - see c64's kung fu flash, an open design for the hardware and the software.

c4cpc is "just" the a cpc's kung fu flash but not freed. So now it's nearly dead, because you can't easily reproduce it without specs.

voilà !

I would really like that. 
I could make my own c4cpc after that.

[Yonivansan]

Hola! Si, es la única alternativa al C4Cpc, pero para que funciona en la consola Amstrad Gx4000 hay que hacer un puente en la placa de la máquina alguién puede explicarlo eso que esta cómo se hace exactamente? He encontrado información pero no lo dejan muy claro hay que soldar o qué hay que hacer para que funcione el Back Bit Pro y saltarse la protección del ACIDO?

Ayuda por favor. 

[dragon]

https://amsnews.fr/2023/10/04/tuto-utilisation-backbit-pro-sur-gx4000/

[overange]

Clever and simple design where a simple adapter makes it work with different systems. In the end, it's probably just a (Teensy?) microcontroller that behaves as ROM and can react on specific actions to load images from SF card into its RAM.

I guess we could use a similar approach with e.g. a Teensy, a few level shifters and a NoAcid IC to come up with a community / Public Domain successor to the C4CPC. As it would not require a FPGA it would be easy to replicate for many - and some will offer it on Ebay for a few bucks more.

The early versions appeared to use a teensy and yes a Teensy can be used as a ROM emulator.

The Acid Mod is interesting, hooking up a link to R90, has anyone figured out how this mod works?

[darkhalf]

@overange I dare say that there is ACID override/emulation in the backbit cartridge as seen in R90 where TOTO is connecting to here to a 'reset' terminal
https://amsnews.fr/2023/10/04/tuto-utilisation-backbit-pro-sur-gx4000/

[darkhalf]

Okay another look at the GX4000 schematic

Pin 156 is the /SRST line which is tied via R90 1K and diode to 5V. It also goes via R91 22K to a weaker NRESET line

So backbit is pulling the /SRST line to probably work around the SIN/CLR ASIC glitch method (where CPCPLus does not reset) as discussed in the other threads

[overange]

I think it is more simpler that we think, on the Atari 8 Bits, the Reset keypress is pulled to ground, and its were you hook your link up to. So either the backbit is looking for the reset signal, or it controlling the signal.

The drawing does say, Required to facilitate ACID Bypass ??

[overange]

I for some reason cannot attach snips/photos, so here is the link to the manual, page 7 is the Amstrad hook up.

https://backbit.io/downloads/Docs/BackBit%20Cartridge%20Documentation.pdf

[eto]

I for some reason cannot attach snips/photos

don't use the "quick reply" function but the "reply" button. Then you will see the option to upload attachments. 
Alternatively, if you already started typing in "quick reply" you can click on "preview" and then the attachment will be possible too. 

So backbit is pulling the /SRST line to probably work around the SIN/CLR ASIC glitch method (where CPCPLus does not reset) as discussed in the other threads

Any idea how that works? Or a link to the other threads?

[darkhalf]

Any idea how that works? Or a link to the other threads?

Without having the Backbit Pro here, we can only make assumptions. Either it would pull it, or listen to it. Page 7 of the backbit manual just mentions

Required to facilitate ACID bypass. Connect jumper to internal reset

There was much discussion on the spanish forums about ACID used to allow memory accessing. Including the CPCPlus generating 'random' numbers used to generate the accesses on the A0-A7 lines for detecting ACID, and then checking the SIN line responses
https://amstradcpc.mforos.com/305097/7723493-que-hace-exactamente-el-chip-acid-de-los-cartuchos

The algorithm worked out by noca$h and posted here (based on feeding Address/_CE etc inputs to the ACID and monitoring the SIN line)

https://www.octoate.de/2010/02/17/acid-protection-decrypted/

btw I wrote some code for Arduino over weekend to simulate the accesses and drive the lines similar to the ACID but could not get it to match the SIN rotational register output just yet

Referring to my original comment. If the backbit used the 'glitch' method mentioned in the second part here
https://www.octoate.de/articles/acid-verilog-code/
originally implemented in the Chinnery cartridge here
https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/amstrad-gx4000-plus-cartridge-pcb/
then the CPCPlus/GX4000 would not soft reset

We discuss in the GX4000 Chinnery thread, other work arounds (shining method) using CCLR to adjust the PRE line on the flipflop as a workaround to allow soft reset. Personally I've not had success with this on my CPC464plus. 

So for backbit, perhaps directly pulling the /SRST line was a different work around. I doubt (based on reading of unlocking ASIC memory access) that this mod alone would unlock the ACID functionality

[eto]

Has anyone looked into the Backpit Pro case? I am really curious what micro controller is used.