about G2 bus

[zero35]

SWAT,i simple browsing DreamShell RC4 at github and seem i found have some new codes like "g2ata" and "g2ide",this shows in the future DS will support it?
curious,how much transfer rate in DC's G2 bus?G2 will be outperform than G1?
but you need to made a physical device like PSIO maybe

[cybdyn]

PSIO-like device or DCIO for Dreamcast uses G1))

G2 can act in two modes:
1- asynchronous, simple access like static RAM, it is slow and no-DMA option.
2- synchronous, it's quite fast (theoretically), it's PCI-like protocol. but it should be researched deeply, there is no much info about it.

anyway, technically, psio could be as device for such simple protocol, like it does in PS1

[SWAT]

It's very old driver for first in DC history IDE mod, it's works slow and just forget about it.

But if compare G1 and G2 bus, then G2 should be faster than G1. But good IDE mod for this bus it's not easy. Need research and use some CPLD.

[cybdyn]

SWAT,
how's about such device? if we start to work on it))
would it be intersting for you?
could you support it by tests, or some one else?

my point, maybe it's faster then SD mod in async mode?

maybe it'll be interesting to add Ethernet on the board too?

[SWAT]

Any devices interesting for me
Ethernet is good, but for real usage need backward compatibility for BBA (for using in games) and it's not easy.
As a storage, G2 device will be too expensive (need CPLD, memory buffer etc), G1 IDE much cheaper (because i/f already exists), and speed is enough.
But for G2 we can make any devices, because it's more universal bus as PCI. So if make devices for G2, it's will be not a storage only, need some more universal like USB.

[cybdyn]

yeah G1 IDE is most simple device)))
as prototype for developers and supporters it's not too expensive.
"CPLD + memory buffer" can be replaced by fpga with internal buffer RAM (~30..50 kbytes, enough for DMA frames). but maybe you meantioned about memory expand - like additional SDRAM 32..64 MBytes?)

no sure about Ethernet soultion, what IC to select : like mcu ARM + Ethernet , or discrette IC.

Advantage of such device could be Plug&Play solution. PCB measurment could be fitted to the case of popular useless Modem device.

[SWAT]

Additional SDRAM it's good too. This has slow access in compare to main RAM or VRAM, but can be used as cache or something.
BTW sound RAM on G2 bus.
Also some ARM CPU (or SOC O_o) on this bus can be useful as AICA.