Subject:
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Re: Dissecting the RCX
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 15 Feb 2002 19:58:31 GMT
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Viewed:
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616 times
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"Rob Limbaugh" <lego-robotics@crynwr.com> wrote in message
news:200202151814.NAA28622@www21.ureach.com...
> After looking up some component data sheets, I've found myself wondering a • few
> things:
>
> 1) The H8/3292 pin 42 connects to the D43256B pin 23. According to data
> sheets, this is A6 from the H8 and A11 on the RAM. Both data sheets show
> address numbering to be A0-A14. Does the RCX access the memory • non-linearily,
> or do I have data sheets for a different version of the D43256 series of • RAM
> chips? (I haven't checked the control pins yet to see if those match up • as
> expected according to the diagrams.)
Actually, it doesn't really matter what order you hook up the address lines
(or
data lines, for that matter) between the CPU and SRAM. The data may get
stored in a garbled manner inside the memory chip, but when read back the
data gets ungarbled and appears correct to the CPU. It can be convenient
when laying out the PCB to rearrange the lines this way.
> 4) Has anyone been brave enough to unsolder the large chips to take • snapshots
> of the hidden traces?
This would help you with deciphering what's happening on layers 1 and 4 of
the
PCB, but layers 2 and 3 may contain some sandwiched traces. These
layers (2 & 3) are often used for power supply and ground, though.
I've had my RCX apart for a couple days, taking pictures and poking around,
too. (Eventually, just about every electronic device in my house seems to
end
up getting opened up for examination... ;-)
Cheers,
Mark
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Message is in Reply To:
 | | Dissecting the RCX
|
| After looking up some component data sheets, I've found myself wondering a few things: 1) The H8/3292 pin 42 connects to the D43256B pin 23. According to data sheets, this is A6 from the H8 and A11 on the RAM. Both data sheets show address numbering (...) (23 years ago, 15-Feb-02, to lugnet.robotics)
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