SidecarT: An Atari ST(E) Cartridge Emulator Supercharged by Raspberry Pi Pico

[logronoide]

Hello Atari enthusiasts,

Excited to introduce SidecarT, a state-of-the-art cartridge ROM emulator meticulously designed for the Atari ST, STE, and Mega series. By tapping into the formidable capabilities of the RP2040 microcontroller housed in the Raspberry Pi Pico, SidecarT offers:

Features:

1. Versatile ROM Emulation: Transition between 64Kbyte and 128Kbyte ROMs effortlessly. With SidecarT, load your desired binary files from a microSD card or directly over Wi-Fi.

2. Real-time Cartridge Bus Interaction: Beyond just ROMs, SidecarT synchronizes with the cartridge bus instantly. This continuous integration translates to an unparalleled data read-write experience, enriching the emulation of devices.

3. Diverse Device Emulation: SidecarT is versatile and is the perfect platform to emulate everything from hard disks and floppy disks to real-time clocks, keyboards, and mouse devices. A holistic emulation journey awaits.

4. Open Source & Customizable: SidecarT operates under the GNU open-source license, ensuring transparency and adaptability. With its open hardware design, you're empowered to modify, refine, and extend its capabilities. It's not just an emulator; it's a canvas for tech innovation.

5. Powered by Raspberry Pi Pico: With the Raspberry Pi Pico's RP2040 at its heart, SidecarT is where classic charm meets modern magic.

I invite every Atari aficionado to participate, be it through testing, code contribution, or insights. Let's shape the future of SidecarT together!

Engage further or contribute directly via https://sidecart.xyz. Also feel free to ask me anything in this thread, happy to clarify any question.

Your ideas and enthusiasm could really help take SidecarT to the next level!!

Stay retro and forward-thinking!
Diego

[sigmate]

This looks fantastic! Congrats!

First thing that comes to mind: sound cartridges emulation! If the RP2040 has built-in DAC (which I’m pretty it has) or with discrete DAC if I2S is also available! That’d require some update on the PCB (to provide an audio output connector at least) but that’d be really fun to explore!

[logronoide]

This looks fantastic! Congrats!

First thing that comes to mind: sound cartridges emulation! If the RP2040 has built-in DAC (which I’m pretty it has) or with discrete DAC if I2S is also available! That’d require some update on the PCB (to provide an audio output connector at least) but that’d be really fun to explore!

Thanks! That looks like a good project to explore. Yes, the RP2040 has a DAC, and there are some examples of sound output using it.

Honestly, I did not even think about this, and I think it's awesome! I would like to explore how to run a Demo in the Atari ST, relying some horsepower on the RP2040, and your sound hack sounds like a good idea!

Can you provide any details about sound cartridges for the Atari ST that I can look at?

[tin]

You‘ll find alot of information about sound cartridges (like Stereo Replay, Replay 16 and many more) at Olivier Gossuins site: http://gossuin.be/index.php/520-et-1040-stx (among other cartridges)

He apparently spent a _lot_ of time reverse engineering those and making all the docs plus his findings available to us. Not to mention he even offered most of them in his shop for very little money.

[Greenious]

Cool project, another thing to look into is dongle emulation, such as cubase.. (viewtopic.php?t=20130)

As for the roms on your web, the descriptions are a bit off imho.
Magic Sac and Spectre GCR are the Apple Mac roms needed for the emulators to work
SMS2 is short for Small Multitasking System 2, and it's an alternative OS.
Subhumans LLS, Multiface ST and explorer are "ripper" carts like Ultimate Ripper.

[logronoide]

Cool project, another thing to look into is dongle emulation, such as cubase.. (viewtopic.php?t=20130&hilit=dongle&start=350)

As for the roms on your web, the descriptions are a bit off imho.
Magic Sac and Spectre GCR are the Apple Mac roms needed for the emulators to work
SMS2 is short for Small Multitasking System 2, and it's an alternative OS.
Subhumans LLS, Multiface ST and explorer are "ripper" carts like Ultimate Ripper.

Don't let an IA do the job of a retro-fan Blame it on ChatGPT!

I asked ChatGPT to fill in the description part of this JSON: https://github.com/diegoparrilla/ataris ... /roms.json

[Greenious]

Lol, I chatted a bit with that ChatGPT but found it... dumb...

Oh, and the mystery1 cart, I honestly don't know what it is/does, it has 2 (very) small programs, ROMON and ROMOFF, it's apparantly made by atari but I know no more.

Regarding power outlets on the cartridge port, be aware that there is a fuse that is connected to it, I believe it's a 1A fuse, but I know quite a few people who's manage to blow it, and then no carts work.

Edit: the cartridge fuse is 500mA

[aag]

I've just signed up for your wait list ( as was trying something similar myself (with esp32/6 address lines only) - think I'll stop and wait for yours!)

I've attached a "hello world" (Steem) rom image - might be of use to someone

My "easy68k" source

Code: Select all

    ORG   $FA0000-4
START
    dc.b    0,0,0,0
     
    ORG   $FA0000     
    dc.l    $ABCDEF42
  

CA_NEXT
    dc.l    0
CA_RUN
    dc.l $08000000+(ROOTBOOT)

ROOTBOOT
  PEA       helwtxt
  MOVE.W    #9,-(A7)
  TRAP      #1
  ADDQ.L    #6,A7 
  
  JMP ROOTBOOT

helwtxt    
    dc.b   'Hello World!',$0D,$0A,$00
    DS 0
    
     ORG    START+$20000-2+4
     dc.b 0,0

    END START

Assmbled code works as steem cart image

SteemShot.png

zip binary

HelloWorld.zip

esp32.jpg

[Cwiiis]

This sounds great, I've joined the waiting list - would this be capable of emulating a Cubase dongle? I think that would be the most immediately useful thing for me, but a future wifi capability would also be interesting, and wifi-accessible storage would be pretty neat too...

[Cyprian]

Just wow!

[sigmate]

Signed up for the wait list as well!

[logronoide]

Regarding power outlets on the cartridge port, be aware that there is a fuse that is connected to it, I believe it's a 1A fuse, but I know quite a few people who's manage to blow it, and then no carts work.

The board consumes less than 200mA. The consumption and some unexpected short circuits (the first prototypes were a jumble of wires!) were a big concern during development. But nothing happened and no Atari ST computers were harmed during the development of the board. Besides, the board integrates a DMG2305UX diode to avoid feeding the Atari ST from a powered Pico from the USB, and vice-versa.

[logronoide]

esp32.jpg

Oh, man! All those wires... I can feel your pain!

[ijor]

Great project. Certainly interested.

It might be useful to add an external switch to enable/disable the cartridge when the computer is on. This would allow to emulate cartridges like the Ultimate Ripper.

[logronoide]

Great project. Certainly interested.

It might be useful to add an external switch to enable/disable the cartridge when the computer is on. This would allow to emulate cartridges like the Ultimate Ripper.

Thank you! It's a great idea, and I think I can do it easily by reprogramming the SELECT button for this specific mode. If I understand correctly, is switching on the ROM emulation at a certain time the point? Is there any other action to do? I have a ROM image of the Ultimate Ripper to test [here](https://sidecart.xyz/roms/).

[Mug UK]

Ultimate Ripper requires you to press a Function key once the rfeset button and then the switch is flipped, either F1 or F2 (from memory). Then it will do it's calculations (black & white flashing lines on screen) before it takes you into its menu.

Whereas (from memory) LLS just requires a reset, then flip the switch. Then you're in an MonST clone (as developed by the team who did Lemmings).

[aag]

There's a good writeup/explanation here

Some games and demos would freeze if they detected that a cartridge was inserted so I had to fit a toggle switch to the cartridge +5v line, so that the reset button could be held down before switching the cartridge on and then releasing the reset button.

https://codetapper.com/atari-st/st-interviews/zippy/

[btp]

Looks like a nice idea!
I applaud your enthusiasm and creativity in this exciting project!

[logronoide]

There's a good writeup/explanation here

Some games and demos would freeze if they detected that a cartridge was inserted so I had to fit a toggle switch to the cartridge +5v line, so that the reset button could be held down before switching the cartridge on and then releasing the reset button.

https://codetapper.com/atari-st/st-interviews/zippy/

Thanks for the info to all of you. It sounds like low-hanging fruit for the next firmware release. I have added this as a feature request: https://github.com/diegoparrilla/ataris ... o/issues/6

[Crazy Q]

could the SidecarT be used as synth and be accesed via midi?

[Greenious]

Thanks! That looks like a good project to explore. Yes, the RP2040 has a DAC, and there are some examples of sound output using it.

Honestly, I did not even think about this, and I think it's awesome! I would like to explore how to run a Demo in the Atari ST, relying some horsepower on the RP2040, and your sound hack sounds like a good idea!

Can you provide any details about sound cartridges for the Atari ST that I can look at?

Sample cartridges were probably the most popular cartridges to be made for atari, followed by clock cartridges.

Atari forum wiki has a small list with info here ; https://temlib.org/AtariForumWiki/index ... d_Samplers

What you need is how these were written to, all of them use the same basic method, but the exact adresses likely varies...
In the case of microdeal stereo replay, the manual have this:

streplayplayback.png

Although I suspect some of the different sound samplers were the same, just rebranded.

You will find more good information in this old thread! viewtopic.php?t=9824

[1st1]

Why not emulating NetUSBee, Ethernet+USB adapter? Or create a new one where the Rapi takes over the whole Ethernet and USB protocol instead of the Ne2000 compatible chip plus TOS/MiNT software driver? (New STing and MiNT drivers required!)

How about emulating copy protection cardridge like Steinberg Cubase 3 / Audio?

How about emulaling Midex and Unitor Midi interfaces for Cubase and NotatorSL?

How about emulating larger drive than 128 kB ROM port, something which makes access to SD-card, independent from DMA/ACSI/SCSI?

[logronoide]

Why not emulating NetUSBee, Ethernet+USB adapter? Or create a new one where the Rapi takes over the whole Ethernet and USB protocol instead of the Ne2000 compatible chip plus TOS/MiNT software driver? (New STing and MiNT drivers required!)

How about emulating copy protection cardridge like Steinberg Cubase 3 / Audio?

How about emulaling Midex and Unitor Midi interfaces for Cubase and NotatorSL?

How about emulating larger drive than 128 kB ROM port, something which makes access to SD-card, independent from DMA/ACSI/SCSI?

- The network emulation I think it's probably low hanging fruit.
- I have been reading the Cubase thread, and it's so obvious that SidecarT was made for loving protection dongles...
- Yes, the emulation of floppies is an ongoing thing, and probably all the second-batch subscribers will enjoy it: https://github.com/diegoparrilla/ataris ... o/issues/7
- Hardisk emulation is harder. I started trying to migrate the Hatari GEMDOS drive project and ACSI2STM GEMDRIVE but it's really challenging... eventually I will get it, but it will be months, not weeks

I'm overwhelmed with the reception. The second batch filled in 24 hours and in 48 hours I have twice the number expected. It's crystal clear the community envisions things I never thought of. And that's great. So if some of the popes/gurus of the topics above want to put their coding skills into the RP2040 code I will gladly send them a board with a pico wh for development (send me a private). And I promise to document for developers and support them.

One more thing: DEMOSCENE. In the Spanish RetroWiki board, we were thinking about the possibilities of SidecarT for demos. I was wondering if it's possible to use the ROM3 and ROM4 address range ($FA0000 - $FBFFFF) in the video base address registers ($ffff8201-03-0d). If so, the possibilities for demoers are immense. If not, we still have the blitter to copy. Anybody knows?

[aag]

I'm not demo coder but believe code running from rom isn't effected by memory/video interleaving, (so no wait states, so code runs quicker. Maybe opportunity for a "sprite record" ?)

[Greenious]

One more thing: DEMOSCENE. In the Spanish RetroWiki board, we were thinking about the possibilities of SidecarT for demos. I was wondering if it's possible to use the ROM3 and ROM4 address range ($FA0000 - $FBFFFF) in the video base address registers ($ffff8201-03-0d). If so, the possibilities for demoers are immense. If not, we still have the blitter to copy. Anybody knows?

No, that isn't possible. The shifter can only be fed data from RAM. This is because how the memory is set up on the ST, with the MMU/Shifter/RAM basically being it's own system, with a bus connecting to the CPU/Blitter/DMA & the rest of the ST allowing them access.

But blitting data from the cartridge port to video is certainly doable, although I fear it would be wasted on pornhub...

However, in my mind I have been toying with the idea of replacing RAM with something like a raspberry, that would simulate the ram for the ST, in theory it would be able to do things like sprites, 3D and other graphic effects in the background aswell as other DMA tasks such as PCM playback, transfers to-from storage media and in theory provide "unlimited" ram through bank switching. But would the ST still feel like an ST after such a mod?