--- Gary Hildebrand <ghldbrd_at_ccp.com> wrote:
> Ethan Dicks covered it as well as I could have.
Thank you.
> The Amiga BTW does use standard 720k MFM floppy drives with the right
> jumpers...
ISTR back in the old days, the issue was the diskchange signal. It
appears on a couple of pins (2? 34?) and _can_ be jumpered for
different controllers, but AFAIK, not *all* "720K" drives have those
jumpers nor bring diskchange out to the connector.
> and if it is externally mounted, a one IC flip flop is added; that IC is
> the source of the notorious drive click, used by the OS to detect disk
> changes.
I thought the IC in the external drives was to permit the OS to see a
unique pattern on one of the lines to ident what the drive size/density
was. The click is caused by the OS moving the drive a track to
trigger the diskchange logic in the drive. I don't recall what the
"no click" fix was that people tended to use, but perhaps it was a
"seek backwards while on track 00" - which on *most drives* was harmless.
The drive already knew that it was on 00 and wouldn't engage the motor,
but _would_ set/reset the diskchange flip-flop. Some drives still
clicked. It was advised not to run "no click" software on them.
> Certain HD drives can be used, but only a couple specific models.
Ones not approved by C=? I'd love to hear which ones. I have a couple
of the "right" ones that I paid about $100 for, new. Probably cost
me about $1 per floppy I read. :-( OTOH, at least a few of those
floppies were probably worth the entire expense.
> The 1200 and 4k have an IDE interface, but you need IDEfix and an
> adapter ($50) to attach anything other than the 2.5" drive to it.
I pick up 44pin<->40pin adapaters for $5 at hamfests, etc. Is there
something odd about the A1200 interface that I don't know about?
The A4K has a standard 40-pin IDE interface. My A4000 has a pair
of IDE drives (120MB and 340MB - *huge* at the time). I was just
happy to get an A4K (I got mine in NZ and converted the PSU by
replacing the guts, when I got home).
> Finding that 44 pin IDE cable is a pain too.
Not in my experience. It's an off-the-shelf item at the guy I
buy my SCSI cables and cable adapters from at the Dayton Computerfest.
I don't think it's more than a few bucks. I've even gotten them
at the crappy shows at the fairgrounds. (I needed two to make an
pin swabber for my iOpener).
> I'd reccommend an A3000, as it has an onboard SCSI controller, and built
> in scan doubler that drives a VGA monitor directly.
I'd recommend that, too, if you aren't AGA-dependent. I never got a
video card for my A3000, so I lived with 1985-era graphics, well into
the 90s. If you can get a newer SCSI chip (rev 8 33C93), all the better.
There's issues with the stock chip and some devices, especially when
disconnects are enabled (to allow slow peripherals like tape to take
their sweet time without hogging the bus).
There's no room inside the A3000 for a CD-ROM, so you'll want to locate
an external SCSI one. I have put two hard disks inside the case, but
it's a tight fit with the plastic push-rod power switch going over the
right-most drive bay (I forget why I couldn't put the HD in front of
the other one, in the left-front bay).
> The other models, expecially the 1200 and 4k, need a DB23 to HD15 pin
> adapter, which are pricey.
I got one with my A1960 monitor. It's trivial to make a replica, but
finding the 23-pin connectors is a problem these days.
> Parts are reltively available for the 3k as well...
Except the static-column 1M ZIP DRAMs... best to get a machine with 18MB
total memory (2MB chip, 16MB fast). There were SIMM adapters, but
all you can find in SIMMs is Fast Page (FPM).
> the 1200 and 4k are notorious for NO parts.
That's true. Better hope you find that A4K with a 2MB CHIP RAM SIMM.
I don't see 2MB SIMMs very often, loose in the wild. 4 x 4MB SIMMs
for FAST RAM are no big deal. Shame they never supported 4 x 16MB.
The only tricky thing about RAM and the A4K is that if you want to
use the lower Zorro slot, you have to use low-profile SIMMs.
Either way, A3K or A4K, if you need Ethernet and you don't get it
from Gary, I can fix you up with a two-slot solution - GG2 Bus+
in the one, NE2000 in the other ("big box" Amigas have native 100-pin
Zorro slots and a few ISA slots for Bridge Cards. The GG2 Bus+
maps the ISA bus into 68K-memory space; works great on the A3K, less
well with certain '060 cards in an A4K due to them trying to cache
the space that the GG2 Bus+ lives in. Got plenty in stock, *new*).
-ethan
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Received on Wed May 22 2002 - 10:03:01 BST