Ampro Little Board questions...

From: Richard Erlacher <>
Date: Sun Dec 16 11:01:43 2001

The BIOS, meaning the lowest-level hardware<=>software boundary, doesn't live in
a ROM as on a PC or many other types of hardware, but, in the case of CP/M is
one of several parts of the OS. Some of them use the ROM contents, while some
don't. Others use it only when they want to, and map it out so they can use
that (scarce) address space in other ways.

This system is NOT a PC. There are, if I understand Don Maslins comments of
long ago, some versions of the Little Board that are, in fact, intended to run
MS-DOS. This may not be one of them.

Perhaps it would be well to open the box, read the numbers on the various items
inside, e.g. Little Board, bridge controller if there is one, hard disk, floppy
disk drive, etc, and share that information with the rest of us. Answers could
then, perhaps, be more directed at the specifics of your situation. It's
unlikely that the software, in any sense, has the perception that "controller"
is "onboard" since there wasn't one. The NCR 5380, unlike the ANA 1542 board in
an old PC, is an adapter, not a controller. Modern (meaning relative to the era
of the Little Board) SCSI drives require a specific signalling protocol. The
NCR5380 provides that signalling protocol, and the software running on the
Little Board does the control task.

The bridge controller has, at one end, the Little Board running its software
and, at the other end, a physical drive that uses ST506/412 protocol. The
pre-1986 "SCSI" implementations, some of which were, in fact, SASI, but are
handled appropriately by the Little Board BIOS, had no "common command set" as
was standardized by the adoption of the SCSI standard, hence the
firmware/software available in the Little Board repertoire is required as a tool
to ensure that the proper functions occur in the desired sequence. Bridge
controllers were VERY popular, and, hence, were available in quite a varied

Unfortunately, the lack of standards, up to the adoption of the SCSI standard,
required that, in the case of the Little Board, among others, the user provide
details about the hardware that invervened between the Little Board and the
media. In the case of a bridge controller, the software has to incorporate
information about the physical parameters of the drive before it can send
appropriate commands to the bridge controller. Later drives, those with the
SCSI connector on them, simply incorporated the rather involved logic on the
bridge controller and the rather simple logic on the drive into a single set of
logic, thereby yielding a SCSI drive. This wasn't widely done, though some
manufacturers risked it, until a standard was adopted. One of the popular
manufacturers of pre-SCSI, but useable in this environment, drives was XEBEC,
who also made drives specifically tailored for use with Apple Computer Co.
products. The write-ups accompanying the data I got from Don Maslin clearly
refers to some of these integrated drives, but I'd caution anyone to be certain
of what they're doing before expecting a pre-1986 drive to "plug-and-play" in
this environment. It's unlikely anything will be damaged, but having the
knowledge will help avoid disappointment.

The SCSI adapter address should be 7, IIRC, (that's certainly the most common
default) and the bridge board should respond to ID=0. The drive, if it's
SCSI/SASI, should be at ID=0, and should be jumpered to respond to DS0 if it's
an ST506/412 model with a bridge controller. The prep program is NOT, IIRC, a
formatter but merely configures your target drive to function within the Little
Board framework. There's a separate formatter program, unless I've forgotten

The floppy disk has absolutely nothing to do with the hard disk interface, BTW,
and the default cable for a floppy disk is a plain and simple,
no-twist-no-cut-no-nothing, ribbon cable with the appropriate connectors at each
end so that it fits. Checking where the ground pins are located will straighten
out any confusion.


----- Original Message -----
From: "ajp166" <>
To: <>
Sent: Saturday, December 15, 2001 9:47 PM
Subject: Re: Ampro Little Board questions...

> >> > From: Gene Buckle <>
> >> Funny, the Ampro docs list all these various controllers and whatnot.
> >> The software also _asks_ what controller it is going to talk to. The
> >> SCSI controller is part of the LB. What would the software consider
> > > the onboard controller to be?
> NCR5380! But that's half the picture. The other half is the SCSI
> Allison
Received on Sun Dec 16 2001 - 11:01:43 GMT

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