Amiga 2500 questions

From: Ethan Dicks <>
Date: Thu Apr 11 09:52:44 2002

--- Doc Shipley <> wrote:
> Hi. I'm looking at an Amiga 2500, with a 5M hard drive, unknown ram,
> a lot of boards in it (the owner knows as little about it as I do), and
> no keyboard, mouse, or display.

Sounds like an early one, but pretty standard.

> He wants $30 for it. He has a display from a Commodore Colt hooked up
> to the composite video port, and the 2500 will boot to a screen with
> hand holding a WorkBench 1.3 floppy shown.

Hmm... needs a boot floppy, then. The disk controller might be an
ancient A2090 (not A2090A w/autoboot) - 5MB sounds like an MFM drive;
I don't think there were any embedded SCSI drives under 20MB.

It might have a bridge card - an A2088, most likely, perhaps an A2286.
If you can look inside, see if the hard disk is attached to a Zorro card
or an ISA card. One dead-giveaway is a 5.25" floppy in the front. That
usually means "bridge card".

> Are keyboards as hard to find as it seems?


> That's the showstopper so far. Is $30 reasonable for a partially tested
> A2500?

If you have piles of Amiga parts, not really. Maybe a bit high. It
depends if he'll come down in price or just trash it if it's too cheap.

I haven't bought an Amiga in a few years (got plenty) so I don't know
what the going rate is these days. Certainly not *over* $30 unless
it has some special cards (8MB Zorro RAM, A2091, A2065 ethernet...)

> Will the kbd/mouse from the Colt work?

The keyboard, absolutely not. It's a standard IBM-XT keyboard. I'm
not sure what model mouse the Colt takes. The Amiga needs a raw quadrature
input mouse with two buttons (at least). It is electrically compatible
with the Microsoft Bus Mouse (different connector), not a serial or
PS/2 mouse. There is no microprocessor in an Amiga mouse, just some
optical hardware (interrupter wheel and some IR LEDs/phototransistors).

Commodore made several flavors of mice - Amiga mice, C-64 mice (with the
"Mickey" chip to let you hang a mouse off of a joystick port) and I'm
pretty sure they made serial mice for later PeeCees. I'm just not sure
what the Colt takes (and I _have_ a Colt - my 8-bit-ISA interface to my
UP600A device programmer is in it, along with an NE1000 to feed data
to it).

If nobody else has a good answer on the mouse, I can probably evenually
dig up the docs on it.

The keyboard is going to be a problem, though. There are designs on
Aminet for building a keyboard protocol converter for an AT keyboard.
I have a commercial one I think cost me $30 (maybe $50).

The monitor is another problem - Amigas use 15KHz natively. You can
use a composite monitor on the mono port, or a NEC Multisync 3D with
a 23pin-15-pin adapter if you can't find a 2002 or 1084, etc. An
ordinary PeeCee multisync monitor won't go below 31KHz.

More modern Amiga chips and OSes will give you VGA-friendly modes, but
that only works once the OS is up. It's a pain to diagnose boot


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Received on Thu Apr 11 2002 - 09:52:44 BST

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