How close can I get MiSTer FPGA to a real Atari 520ST

[cathrynmataga]

How close can Mister get to a real Atari 520ST with all the hardware connections functioning. What I see from browsing the forum.
1. Joysticks, yes. I think these work. I think I can find a 9-pin compatible USB connector for this somewhere.
2. Midi, yes, or at least it's actively being worked on. I see nice activty in the midi topic here. Not sure if I need special hardware or a generic PC USB midi device, but it looks like it's coming along and people are thinking about this.
3. Serial. Maybe? I'm not sure. I see references to Serial port, but haven't seen anyone hooking real RS232 devices up. Will a USB Serial port work with Mister?
4. Parallel. Maybe? I' guess not -- are there USB centronics ports that will work?
5. Floppy disks. I guess not. That Atari ST DIN connector is so weird. I don't see anyone talking about support for physical floppy drives.
6. SCSI hard disks. No idea? I guess not but maybe? Is there a USB to SCSI adapter out there? Can this function?
7. Cartridge port. I assume not, or at least someone would have to build the hardware? Is ST cart port a standard edge connector?

[Bas]

USB will first and foremost be managed by the Linux kernel running on the MiSTer. That gives options for translation and adaptation between the running cores and the physical hardware. As long as you can pump the bits fast enough, it should be doable theoretically. For things like a cartridge port, you're probably looking at pin shortage. Things will be too timing critical to pass through the ARM side of things.

As for SCSI, Adaptec actually has USB/SCSI adapters. If these work without issue on Linux, it may become possible to present your physical SCSI hard drive to the ST core but that won't be easy and probably also not very fast. Cloning such a disk will be easier. As for things like scanners, that'll be a massive challenge to do within timing constraints.

[cathrynmataga]

To me, for consoles, the controller is enough. But PCs are kind of about interfacing to other hardware. Serial/parallel, maybe possible just at the tinkering level, sounds like. Maybe easier than Midi, and actually the one I really miss is serial. Floppy drive might work badly, but all the copy protection and timing hassle.

Some things just have to talk to FPGA directly. LIke, 'in the future' what we need is some kind of hardware solution to natively support cartridges and direct high speed I/O like the ASCI. Some way to interface to all those pins without too much hassle. Atari ST has one of the most useless cart ports ever, but like I don't think I could live with Atari 8bit without a cart port. Other platforms would benefit from this, but I'm not sure what it'd look like. Maybe that would have to be another platform? Not sure.

[Sorgelig]

Emulation it mostly targeted to play games. It still can be used beyond playing, but expansion ports are mostly virtual connected internally to emulated external devices.

For full feature set emulation it's better to create a completely different platform. It still can use FPGA, but it should use mainboard with same expansion connectors. And it should use a single core only, so there won't be conflicts with external devices.

[cathrynmataga]

I suppose that's what Ultimate-64 is for C64, though this is quite the project. This guy got pretty close to an exact copy of the C64, and I believe it will take cartridges. I don't think this was an easy thing to design.

[Sorgelig]

Nope, it's not hard to add original HW ports. These ports are present inside the core anyway. It just depends what you want to achieve. U64 is designed to replace original C64 board, so it perfectly fits original C64 case with all ports. But you can't run for example ZX Spectrum core on that board as it won't match ZX main board. So U64 is targeted for a single C64 core. Other cores may run but will work the same way as on MiSTer with all ports being virtually emulated inside. And since MiSTer is originally planned as universal emulation platform, it doesn't use platform specific ports.
Still some low-pin number ports like serial or midi can be output through USER_IO. Slow parallel ports are possible through serialization using SPI or I2C over USER_IO.