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1997-05-31
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___________________
ZeriLink user guide
___________________
User, please note
=================
ZeriLink is Freeware, i.e. it is free software.
Copyright notice
================
The copyright (c) of this program belongs to John Kortink. All rights are
reserved.
You may not change this program (except for documented configuration
changes). You may not use any part of this program in any other program or
product without my written approval. You may spread this program freely, but
only in complete and unchanged form, and only against bare distribution costs
(if any). This program is provided 'as is'. No fitness of this program for
any particular purpose is implied. Using this program is entirely at your own
risk.
//
//
// Introduction
//
//
ZeriLink provides a robust and fast (up to 800kB/sec) file transfer link
between two Acorn machines, two IBM compatible machines, or one Acorn and one
IBM compatible machine. ZeriLink's only requirement is that both machines
have a parallel port that supports either ECP or PS/2 mode. Most Acorn and
IBM compatible machines support at least one of these parallel port modes.
ZeriLink has been developed on an Acorn RISC PC and a generic IBM compatible
'clone' PC. Both machines have a parallel port that supports both ECP and
PS/2 modes. Apart from a successful link between a HP Vectra machine and my
Acorn RISC PC, I currently don't know about other combinations that will
work, so I cannot give definite guarantees that ZeriLink will work on your
Acorn or IBM compatible machine(s). The Acorn RISC PC should work in either
ECP or PS/2 mode. The Acorn A5000 and Acorn A4 will *probably* work in PS/2
mode (but will not work in ECP mode). Once I get positive results from users
I will compile a list of compatible machine types.
The hardware side of the link simply consists of a suitably wired parallel
cable, which is plugged into both machines' parallel port. The ZeriLink
software provides convenient commands to transfer files between the two
machines, across this cable.
In the following, IBM compatible machines will mostly be referred to by 'IBM'
and Acorn machines by 'Acorn'.
//
//
// Hardware requirements
//
//
Acorn
-----
- A parallel port with ECP or PS/2 support.
IBM
---
- A parallel port with ECP or PS/2 support.
- An Intel 80386 or compatible processor.
- An environment with DPMI memory management support.
Additional
----------
- A parallel cable wired to specifications. See below.
//
//
// Using ZeriLink
//
//
On an Acorn, the 'ZLink' module and its configuration file 'LinkConfig'
should be installed, preferrably in the !Boot sequence. The 'ZLink' module
provides the 'LinkT', 'LinkR' and 'LinkConfigure' *-commands. Acorn
installation and use is discussed below.
On an IBM, a configuration file called 'Link.CNF' and two executable files
called 'LinkT.EXE' and 'LinkR.EXE' should be installed in one of the
directories pointed to by the PATH system variable. IBM compatible
installation and use is discussed below.
It is important to note that the ZeriLink software is fully sufficient to
link any one of three combinations of machine types (Acorn to IBM, Acorn to
Acorn, or IBM to IBM). The 'receiver' software on a machine is capable of
interpreting both 'native' files (which will be left untranslated) and
'foreign' files (which will be suitably translated to 'native' format). The
'transmitter' software simply sends its 'native' format only.
The parallel cable which connects both sides' parallel port consists of a
'male 25 pin D' plug on both sides, and a multi-wire *SHIELDED* cable. The
cable should be wired as follows (pin numbers are marked on the plugs) :
Pin 1 (nSTROBE) <---> Pin 10 (nACK)
Pin 2 (DATA 0) <---> Pin 2 (DATA 0)
Pin 3 (DATA 1) <---> Pin 3 (DATA 1)
Pin 4 (DATA 2) <---> Pin 4 (DATA 2)
Pin 5 (DATA 3) <---> Pin 5 (DATA 3)
Pin 6 (DATA 4) <---> Pin 6 (DATA 4)
Pin 7 (DATA 5) <---> Pin 7 (DATA 5)
Pin 8 (DATA 6) <---> Pin 8 (DATA 6)
Pin 9 (DATA 7) <---> Pin 9 (DATA 7)
Pin 10 (nACK) <---> Pin 1 (nSTROBE)
Pin 11 (BUSY) <---> Pin 14 (nAUTOFD)
Pin 12 (PE) <---> Pin 16 (nINIT)
Pin 13 (SLCT) <---> Pin 17 (nSLCTIN)
Pin 14 (nAUTOFD) <---> Pin 11 (BUSY)
Pin 16 (nINIT) <---> Pin 12 (PE)
Pin 17 (nSLCTIN) <---> Pin 13 (SLCT)
* Pin 18 (0V) <---> Pin 18 (0V)
* Pin 19 (0V) <---> Pin 19 (0V)
* Pin 20 (0V) <---> Pin 20 (0V)
* Pin 21 (0V) <---> Pin 21 (0V)
* Pin 22 (0V) <---> Pin 22 (0V)
* Pin 23 (0V) <---> Pin 23 (0V)
* Pin 24 (0V) <---> Pin 24 (0V)
Pin 25 (0V) <---> Pin 25 (0V)
In addition, on each connector seperately, pin 13 (SLCT) should be connected
to pin 15 (nERROR) by a short piece of wire.
Connections marked with a * are not required, but they are recommended. In
addition to these connections, the shielding wire should be soldered to the
plug's metal on both sides (i.e. to the plug itself, not one of its pins).
It is recommended to buy a prefabricated completely wired 'straight' parallel
extension cable (i.e. pin 1 to pin 1, pin 2 to pin 2, ..., pin 25 to pin 25),
and re-wire that to the specifications above. This saves a lot of soldering.
Ensure that both sides of the prefabricated cable have 'male' plugs (i.e.
plugs with pins, not holes), that the cable is shielded, and that the plugs
can be opened for re-wiring (some cables have moulded plugs which cannot be
opened).
//
//
// The software on both sides
//
//
The general ZeriLink tranfer concept is as follows :
1) The receiving side issues the 'LinkR' command.
This starts waiting for a transmission from the other side.
2) The transmitting side issues the 'LinkT <filespec>...' command.
This starts transmitting files, one after the other.
3) The transmitted files are received, interpreted and saved.
4) The transfer is terminated (LinkR exits, LinkT exits).
The receiving side needs to issue 'LinkR' because ZeriLink software uses
'polled I/O', to make the fastest transfer speeds possible. ZeriLink achieves
transfer speeds of up to 800kB/sec (ECP mode) or 200kB/sec (PS/2 mode), for
large-ish files.
When files are transmitted, all relevant information about the file is
included and is retained (as well as possible) in the file on the other side.
There are, however, restrictions, which will be discussed below. Also, file
attributes are always ignored. This is because e.g. 'locked' or 'read only'
files are usually a big pain to work with. If you really, really, really need
to preserve file attributes, then archive the files at one end, transmit the
archive, and unarchive the files at the other end.
The ZeriLink software can be configured in a very flexible way, by means of a
configuration file ('LinkConfig' (Acorn) and 'Link.CNF' (IBM) are examples of
generally usable configuration files). The configuration of the ZeriLink
software is discussed below (which options are available depends on whether
the software runs on an Acorn or on an IBM). In general, the configuration
file simply consists of a number of lines. If a line starts with a letter, it
is a definition line (i.e. it contains configuration information), else it is
a comment line (i.e. it is ignored). A definition line starts with a keyword,
and is followed by one or more values. The relevance of each keyword and its
possible values is discussed below. The example configuration files include
detailed explanations of the keywords.
The keyword 'Mode' is a general keyword. It selects either ECP (value 'ECP')
or PS/2 (value 'BIDIR') mode. It is strongly recommended to first try the
'BIDIR' setting, and, when this works, the 'ECP' setting (if appropriate). If
the 'BIDIR' setting does not work, the 'ECP' setting is also very unlikely to
work. Conversely, if the 'ECP' setting works, the 'BIDIR' setting is very
likely to work too.
File data integrity is ensured by a CRC32 algorithm (32-bit Cyclic Redundancy
Check). If the received file data fails this check, it is corrupted, and the
file will be deleted. If the received file data passes this check, it is
extremely unlikely that it is corrupted.
Note that only leafnames of fi