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Expansion Port Info On the V500 V2+ and V4

Andy Hearn

Posts 374
29 Oct 2018 10:03


Hey all,
just curious, and want to understand a bit more as to how this all works.

the V2+ exp port and the SD card slot interface with the FPGA in the same way right? hence SDnet.device and v2exp.device working with the same network hardware.

looking at the throughput I get on the v2exp.device downloading stuff on aminet - about 100kilobytes a sec, could an expansion board be built for the standalone V4 (and maybe even work on the v2 as well) to take the role of the standard internal/external ports? maybe even host internal keyboard ports as well?

even running all the serial, parrallel, floppy ports at once I don't think you'd need anything faster than 100KB/s...



Samuel Crow

Posts 424
30 Oct 2018 09:11


It's an SPI interface.  It's industry standard.
EXTERNAL LINK


Andy Hearn

Posts 374
30 Oct 2018 09:34


ahhhhaaaaaa I did figure it was something like that but didn't twig where to start.

ok, so pretty much anything can bolt on there, but would it need drivers? or could it have a controller on there to replicate dedicated amiga ports? For example, I know Paula is now implemented as Pamela, but could a floppy port adapter be built to plug in to this to allow floppy booting?

could I get a serial port for some 4player lotus2; is what i'm trying to ask :D


Samuel Crow

Posts 424
30 Oct 2018 10:10


I think the only way you wouldn't need drivers for it is if Gunnar put special support in the FPGA core for a breakout board.  Otherwise, you'll need to hack up some drivers in one way or another.

Rerouting serial.device in system-friendly software would be as simple as writing a serial.device replacement and putting it in place of the original.  If Lotus2 bangs the serial port in hardware, FPGA support will be needed.  It might be very little different than adding USB support for joysticks though because the stand-alone will have USB ports, I think.


Andy Hearn

Posts 374
30 Oct 2018 10:26


ah, yeah that makes sense. the backend for hardware level support for external interfaces would need internal FPGA programming and configuration. with ya. the communication to the outside world would be going on over the SPI bus, but at that lowlevel, invisible to the amiga software - be it OS level drivers, or banging the metal, providing the "hardware" does what it's supposed to.
kinda sums up all computing devices there really! :D

the USB implementation is going to be interesting. is it going to be available at boot time? given that the controller is going to be (i'd imagine), in the FPGA anyway. Is it going to be like the Deneb card where boot devices and (afaik), input devices were available in the early startup environment? or like the subway/rapidroad/etc. where you needed to load a USB stack and all the USB classes/device drivers before your machine could talk to anything on the bus?

wait and see I guess... at least with FPGA, it's all possible :)

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