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Author Topic: A500+ Rev 8a mobo IDE I/F?  (Read 1444 times)

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Offline LoadWBTopic starter

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A500+ Rev 8a mobo IDE I/F?
« on: August 07, 2007, 04:03:02 PM »
I finally got my hands on a real NTSC A500+ mobo.  It's not in the best condition and I don't know if it works just yet, but it is full NTSC.  I also got the A500+ service manual and came across something really interesting in the schematics.

CN15 is is a 4-pin connector labeled as "IDE I/F", and has XRDY, _OVR, and _INT2 signals.  Can anyone shed some light on what this is/was supposed to be?
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Offline Zac67

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Re: A500+ Rev 8a mobo IDE I/F?
« Reply #1 on: August 07, 2007, 05:54:15 PM »
Found it in the SM (page 5-7), no idea if this is for a HDD interface...
_OVR is "override system decoding" (switches off Gary's CS outputs)
_XRDY is "external data ready"

Does make sense in a way to build an IDE I/F on top of that, but most is still missing (access to data & address bus, CS generation, latches - the busses aren't even available at Gary's socket). The only sense it'd make is to supply missing signals to an IDE adapter in the CPU socket, in order to avoid ugly (and error prone) 'flying' wires on the board.  :-?
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Offline bobamu

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Re: A500+ Rev 8a mobo IDE I/F?
« Reply #2 on: August 07, 2007, 05:59:08 PM »
thought _OVR was for overlay

for when the system is booting up and the first thing it sees is the rom, before it's "moved" up to it's normal location?
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Offline Doobrey

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Re: A500+ Rev 8a mobo IDE I/F?
« Reply #3 on: August 07, 2007, 06:03:12 PM »
Quote

bobamu wrote:
thought _OVR was for overlay


Nope, that's _OVL
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Offline rkauer

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Re: A500+ Rev 8a mobo IDE I/F?
« Reply #4 on: August 07, 2007, 07:21:23 PM »
Why bother with some strange conectors on the mobo?

 There are , at least, two IDE (three?) IDE interfaces on Aminet to make your own, de-conectable IDE interface for A500/2000.
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Offline bobamu

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Re: A500+ Rev 8a mobo IDE I/F?
« Reply #5 on: August 07, 2007, 08:08:47 PM »
yay

things with similar names leads to confusion :crazy:
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Offline LoadWBTopic starter

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Re: A500+ Rev 8a mobo IDE I/F?
« Reply #6 on: August 07, 2007, 08:25:55 PM »
Quote
rkauer wrote:
Why bother with some strange conectors on the mobo?

 There are , at least, two IDE (three?) IDE interfaces on Aminet to make your own, de-conectable IDE interface for A500/2000.


If this was indeed intended for an IDE drive interface, it could have been a "for future expansion" thing.  But it would seem to make sense if this port presents lines which are not available at the CPU for a CPU-socketed IDE interface, and the like.  I'd be interested in knowing if any of the IDE interfaces on AmiNet require the OVR, INT2, and XRDY lines.

But the AdIDE seems to work well, so it's probably not such a big idea.  None the less, seeing it in the schematics was very intriguing and piqued my curiosity as to the intent of the connector.
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