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  1. E

    SCU DSP documentation

    You pinged me via PM, but since there's a thread I guess I'll just post my response here. I tried to dig up some documentation/tools back in the day, and always wanted to try a "DMA 'through' the SCU DSP" method (i.e. SCU DMA directly to the DSP data port, which I thought should work), but I...
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    new saturn developer

    There isn't literally a register for the CPU tick, but ISTR that there is a "free running timer" that more or less represents the CPU clock run through a configurable divider. I don't have the manual handy (I tried to look it up, but it seems like Renesas has tossed the relevant product line...
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    An exciting development

    That's pretty cool. If I understand it correctly, the basic method had occurred to me a few years ago, but I didn't have any real idea whether it would work and didn't have a Saturn board I was willing to sacrifice. I wonder if a closer analysis would reveal any interesting bits that could be...
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    Another Saturn SDK

    I don't recall having to do anything special to link COFF objects into an ELF executable either. As I recall the main point of writing libbfd was for the linker itself to not care about file layout details as long as the necessary metadata was present somewhere.
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    SATNKernel

    It's precisely the smaller systems (like the SuperH controllers with 4KB instead of Saturn's 2MB) where this would turn into a major problem.
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    SATNKernel

    Yeah; I've long regarded it as a "what if the 68000 were more RISCy?" design, and it's probably not a coincidence that several arcade companies switched from 68000 to SuperH in some capacity, though that may simply have more to do with Hitachi being the main 68000 vendor in Japan.
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    How to read certain memory values?

    There are Saturns with EPROM IPL? Guess I haven't disassembled enough of them.
  8. E

    returning to PAR menu

    Ah, yeah, I got the entry points mixed up; I was talking about the AR copy code being position-independent.
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    returning to PAR menu

    I'd have to look at it again, but I'm not sure that's strictly right; IIRC, the code there normally runs from RAM, and is just position-independent by happenstance. edit: plus, ideally you'd want to check for an executable cart first (e.g. by checking for the "SEGA SEGASATURN" string at...
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    PAR Master code - why and how it works ?

    http://wiki.yabause.org/index.php5?title=ActionReplay
  11. E

    NEOGEO X !!!

    Wasn't this originally teased ~6 months ago? Anyway, this mostly looks like a Dingoo with a Neo Geo logo slapped on it. The list of games looks like it was chosen to maximize the number of games that could be fit into cheap onboard flash storage. They get that the Neo-Geo brand still has...
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    USB dev cart project

    3.3V interfacing crossed my mind, but at that point I start to lean toward plugging everything into a XC9500XL. And then I usually get carried away with the possibilities opened up by that (e.g. turning A-Bus transactions into bursts on faster 8-bit memories).
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    USB dev cart project

    Come to think of it, having those '245 chips at all seems to be redundant (isn't everybody speaking 5V CMOS?), but I might be missing something. As for RAM, that would probably about double the complexity of the cartridge (IIRC about half the chips in the AR4M+ are for implementing the RAM cart...
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    USB dev cart project

    I've only skimmed it so far, but a few things do confuse me a little: Why are U11 and U13 are necessary (it looks like they're supposed to inhibit read/write signals to deselected chips, which should ignore those signals anyway)? How is DATA0_CE supposed to work? (it seems like you want...
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    Communicate with DB25-free Action Replay ?

    That's odd; I've only ever heard of / seen one status bit visible on the Saturn side, which would be connected to bit 0. I wonder what the other bit is. ISTR that the /ACK signal is combinational and only pulses on a write of the output address, so I don't think it would be that. I don't see how...
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    Communicate with DB25-free Action Replay ?

    Yeah, I meant to reinforce that point, not dispute it. I just meant to dispute the "status bit" label because IIRC the cartridge side of it is unburdened by any baked-in dependence on the standard comms protocol and its concept of status/busy/ready/whatever.
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    Communicate with DB25-free Action Replay ?

    I'm not sure about this, but IIRC the "status bit" is actually just a dedicated input pin as far as the cartridge knows (with the actual status bit being stored in a flip-flop on the comms card). edit: I guess what I'm getting at here is this: if you only need one input pin for MISO, it seems...
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    My new project is up!

    I'm pretty sure I did see some stuff about SCU DMA restrictions in one of the TBs, but it's been a long time. edit: see TB #10. There are a bunch of non-obvious restrictions.
  19. E

    My new project is up!

    Most assemblers that I've used don't seem to even bother with a proper grammar; they seem to just go line-by-line and have fairly brittle parsing of each line. A lot of them will barf if an instruction line doesn't start with enough whitespace, for example.
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    how can i upgrade the ram chips on the sega gen 1 model

    It's been some years since I looked at this, but did those chips actually have muxed address pins like DRAM? Otherwise in principle it would make sense to just cut the crap and replace them with SRAM, since modern PSRAMs are mostly high-density low-voltage chips made for cell phones. Any chance...
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