Path: utzoo!attcan!uunet!super!udel!princeton!njin!rutgers!mailrus!ncar!ames!oliveb!amiga!kodiak
From: kodiak@amiga.UUCP (Robert R. Burns)
Newsgroups: comp.sys.amiga
Subject: Re: detachable keyboards and the A500
Keywords: detachable keyboard A500
Message-ID: <2884@amiga.UUCP>
Date: 14 Sep 88 18:29:56 GMT
References: <6397@pyr.gatech.EDU>
Reply-To: kodiak@tooter.UUCP (Robert Burns)
Organization: Commodore-Amiga Inc, Los Gatos CA
Lines: 48

In article <6397@pyr.gatech.EDU> davidc@pyr.gatech.EDU (David Carter) writes:
)                ...  However, pressing control-A-A on a B2000 produces a
)"shutdown" keyboard message; the A500 generates a hard reset signal, and
)does not produce the "shutdown" message.  While a B2000 keyboard might
)still be able to reset an A500 (I'm about to try this), I'd personally
)prefer to keep the hard reset capability.

The A500 and B2000 keyboard roms are different.  The B2000 sends two reset
keycodes to the keyboard.device and waits either for a handshake to those
codes, or a timeout interval (around 1/4 minute, I think) before pulling on
the reset line.  This was designed to let critical system code hold off
reset in the middle of an operation -- the trackdisk.device is a client of
this service but I'm not sure what it does.  The A500, on the other hand,
does not send these reset keycodes or wait around: it pulls on the reset
"right away" (it's actually a capacitor bleed circuit).  The only time you'll
notice a difference (because you never reset in the middle of a disk write,
do you?) is if the processor is so lost that the keyboard handshake is held
off -- have you ever hit a dead B2000 and thought "I thought I hit
CTRL-AMIGA-AMIGA correctly, humm, well, I'll try it agai... Oh! there it
goes...".  That's why the timeout exists in the B2000 keyboard.

)So the "even easier" way to make the A500 keyboard detachable is to get
)an empty keyboard case from a B2000.  You'll still need the connectors and
)a coiled cable (7 conductors plus shield; the A500 has 8, but one is a no-
)connect).

I've got my A500 keyboard extended w/ 3' of ribbon cable and no ground strap
connection.  Works fine.  (Your mileage may vary.  Warrenties not included.)

)This isn't really "easier" because, as far as I've been able to determine,
)Commodore doesn't sell just the B2000 keyboard case as a replacement part.

I admit, I've got an inside source.  I did use it for quite a while sans case
but finally we had a B2000 keyboard go defective so I snagged the case.  I
wish I'd had a better tool than a drill and an xacto to cut those led holes.
I had to nibble a small tab of the metal on the A500 keyboard, but overall
am satisfied with the results.  (Now if only my Return key was more reliable).

We use A500s here for 1.4 testing because they are easier to instrument w/
a state analyzer and they've got the SOTS connector that our old development
hardware connects to.

- Kodiak
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