ChanServ changed the topic of ##yamahasynths to: Channel dedicated to questions and discussion of Yamaha FM Synthesizer internals and corresponding REing. Discussion of synthesis methods similar to the Yamaha line of chips, Sound Blasters + clones, PCM chips like RF5C68, and CD theory of operation are also on-topic. Channel logs: https://freenode.irclog.whitequark.org/~h~yamahasynths
<fseidel>
question for the 6502-inclined in here: why do so many 6502 reset routines start with SEI? The 6502 comes out of reset with I set, so that instruction should be redundant
<fseidel>
not just vanilla 6502 either, every PC Engine game I've seen starts with an SEI too, and HuC6280 sets I on reset
<Foone>
the 6502 did have a lot of errata, maybe some of them didn't come out with reset with I set?
<andlabs>
probably best practice from other chips too
<andlabs>
and also some systems do not boot directly into a sei instruction
<fseidel>
alternatively, thinking it might be so that you can JSR/JMP into the reset vector and have it work as expected
<ej5>
6502 doesn't have a true reset signal, lots of registers come up uninitialized
<ej5>
so you have to sei (and typically cld) to make sure the status register is in a functional state
<fseidel>
right, but the datasheet says that I is set on reset
<fseidel>
I think it's the _only_ register with a known value on reset, besides PC
<sorear>
i feel like i saw fseidel's explanation somewhere years ago
<fseidel>
wait, I found this at some point and forgot sometime between then and now?
<andlabs>
and I just checked; the sockets I have only go up to DIP40 :/ gotta buy some DIP48s...
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natawie is now known as natarii
<andlabs>
gnat a lee
<natarii>
o/
<ej5>
fseidel, looks like you're right. even in the NMOS version there's a signal called brk-done that forces the internal I flag latch to the set state. brk-done asserts at the end of a brk cycle which is triggered either by the instruction or by the reset signal itself
<ZrX-NoMs>
A good coding practice.
<sorear>
> signal called brk-done
<sorear>
we have design documents for the NMOS 6502 now? I knew we had masks a few years ago but those didn't come with any names or theory of operation
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<cr1901_modern>
Guessing that name brk-done comes from the visual6502 netlist?
<andlabs>
yeah any signal names are likely unofficial
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<balrog>
ej5: how does RDRAM work? :)
<balrog>
it's a major piece of the history of DRAM, mainly because of the N64 and because of Intel and the P4 and the patent crap around that
<balrog>
Pentium 4, not P4
<ej5>
yeah brk-done is off visual 6502. technically i got it off my schematic but that's based on visual 6502.
<ej5>
never looked into RDRAM.
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<balrog>
Rambus had patents on SDRAM and DDR tech that they snuck into the standards
<balrog>
but before that, they managed to get a bunch of companies to use their proprietary RAM
<balrog>
the two major ones being Nintendo, in the N64, and Intel, on most Pentium 4 boards before a certain point when they switched over (some boards supported RDRAM or DDR)
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<cr1901_modern>
ej5: Any hints for attaching shitty LA probes to an ISA card before I throw my probes out in rage?
<ej5>
to the bus? or to arbitrary points on the card?
<cr1901_modern>
arbitrary points on the card
<cr1901_modern>
(answer might be "buy better probes"- I have eight good ones, but the rest are shit)
<cr1901_modern>
Oh right... there is NO logistical way I can attach the card to the board before inserting the probes
<cr1901_modern>
^... just kidding, I managed to do that
<cr1901_modern>
I used a compromise... shitty probes where I can, good probes where the shitty probes. Just. Wouldn't. Attach.
<ZrX-NoMs>
Microprobes?
<ej5>
get an extender card
<cr1901_modern>
This really does not bode well for debugging in the future...
<balrog>
solder wires to the points and clip the probes to said wires
<cr1901_modern>
huh... I might just do that.
<cr1901_modern>
balrog: There's also this amazing thing I didn't consider >>
<cr1901_modern>
verify continuity for the chip in question and place the probes wherever convenient
<cr1901_modern>
These are too slow for transmission line effects anyway
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<andlabs>
I've brought up colorful analog computers in the past