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1992-11-02
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ATARI 8 BIT HARD DISK EMULATOR
Version 1.2
USER GUIDE
November 1991
Acknowledgements:
I would like to acknowledge the excellent work of Nick
Kennedy in pioneering the design of the hardware to
connect the ATARI to a PC and without which this program
could never have been started. Whilst this program
contains entirely different code to Nicks' SIO2PC
software it retains the look and feel of his original
program so all praise to him for the original idea.
The main menu program was written and compiled using the
Microsoft BASIC Professional Development System and uses
Microsoft run time library code during its execution.
The serial port handler and command interpreter were
developed using Borland Turbo Assembler.
Debugging would not have been possible without the
extensive use of Microsofts' Code View product.
1
1. Overview . . . . . . . . . . . . . . . . . . . . . . . 3
2. Installation. . . . . . . . . . . . . . . . . . . . . 4
3. Starting the Emulator. . . . . . . . . . . . . . . . . 4
3.1 No configuration files. . . . . . . . . . . . . 5
3.2 Default configuration file exists. . . . . . . . 5
3.3 Named configuration file. . . . . . . . . . . . 5
4. Screen Display . . . . . . . . . . . . . . . . . . . . 5
5. The Main Menu. . . . . . . . . . . . . . . . . . . . . 6
5.1 F - Create Floppy Disk. . . . . . . . . . . . . 6
5.2 H - Create Hard Disk. . . . . . . . . . . . . . 7
5.2.1 SpartaDos X. . . . . . . . . . . . . . . 7
5.2.2 SpartaDos 3. . . . . . . . . . . . . . . 8
5.2.3 MyDos 4.50. . . . . . . . . . . . . . . 8
5.3 L - Load Disk . . . . . . . . . . . . . . . . . 8
5.4 U - Unload Disk. . . . . . . . . . . . . . . . . 9
5.5 X - Exchange Disk. . . . . . . . . . . . . . . . 9
5.6 R - Make Disk Read Only. . . . . . . . . . . . . 9
5.7 W - Enable Write to disk. . . . . . . . . . . . 9
5.8 S - Set Port Number. . . . . . . . . . . . . . . 9
5.9 D - Display directory. . . . . . . . . . . . . . 9
5.10 Q - Quit Program. . . . . . . . . . . . . . . . 10
5.11 T - Toggle Line Status Display. . . . . . . . 10
5.12 C - Create/Amend Configuration . . . . . . . . 10
5.13 P - Print Through Mode. . . . . . . . . . . . . 10
6. Configuration Files. . . . . . . . . . . . . . . . . . 11
6.1 Creating a Configuration File. . . . . . . . . . 12
6.1.1 Set port address. . . . . . . . . . . . . 12
6.1.2 Load drives D1: - D8:. . . . . . . . . . 12
6.1.3 Default Directory Specification. . . . . 12
6.1.4 Time-outs. . . . . . . . . . . . . . . . 13
6.1.4 Display Status Line. . . . . . . . . . . 14
6.1.5 Loading an existing configuration file. . 14
6.1.6 Saving your changes. . . . . . . . . . . 14
6.1.7 Exit. . . . . . . . . . . . . . . . . . . 14
7. Time and Date Support. . . . . . . . . . . . . . . . . 15
8.File Transfer Utilities. . . . . . . . . . . . . . . . 16
8.1 The PCTFR program. . . . . . . . . . . . . . . . 16
8.2 The File Transfer Interface. . . . . . . . . . . 17
9.Problems . . . . . . . . . . . . . . . . . . . . . . . 19
2
1. Overview
HDEMUL is a program which runs on an IBM PC or compatible
and uses the hard disk of your PC to provide between 1 and 8
disk drives for your 8 bit ATARI.
Connection between the ATARI and PC is made through the
SIO2PC hardware adapter which joins the ATARI SIO port to the
PC serial port. This hardware was designed by a guy called
Nick Kennedy and is described in the SIO2PC distribution pack.
Please note that the SIO2PC software and hardware are
Shareware products and the appropriate royalties (currently
$10) should be sent to Nick Kennedy, 300 South Vancouver,
Russellville, AR 72801 before using them.
HDEMUL is different to SIO2PC in one important respect.
SIO2PC uses PC RAM to provide simulated disk drives up to
184K. This restricts the user to 3 or 4 drives depending on
the amount of spare RAM available. HDEMUL actually reads and
writes to the hard disk of the PC. It can provide up to 8
drives and each drive can support a disk up to 16 Megabytes in
size. The size of the free space on your PC disk is the only
limitation with HDEMUL.
The interface runs at 19.2 KBits per second, which is the
standard ATARI SIO rate. Its performance (on my PC at least)
is faster than a 1050 drive but very much slower than a proper
parallel hard disk interface.
The program performs ALL disk accesses via MSDOS
interfaces and should not represent a hazard to the rest of
your PC software. It will support any valid MSDOS path name
and can be used with PC floppy drives.
The program will require MSDOS 2.0 or later. It was
tested using both MSDOS 3.3 and DRDOS 5 running on an 80386
processor at 16 MHz. It was also tested with the clock rate
slowed to 8MHz without significant loss of performance.
At the ATARI end no additional software is required for
normal disk operations. The interface is at the level provided
by a standard drive e.g. read sector, write sector, etc. It
should thus be compatible with all normal software and all
versions of DOS.
The program will NOT support ultra speed IO or any form of
copy protection (bad sectors, phantom sectors, sector skewing
etc.). It will support all 1050 drive commands together with
extensions to allow double density and hard disk working.
The program was tested with DOS 2.0, DOS 2.5, SpartaDos 3.1,
SpartaDOS X and MYDOS 4.5. It has been used with a fair range
of word processors, sector editors and unprotected games
programs without problems.
I do not own an XF551 drive and have absolutely no idea
whether the program is compatible with this device.
The emulator can be used in conjunction with real drives on
the same SIO chain provided there is no clash between the
drive number of a real and emulated drive.
3
The following facilities are available within the HDEMUL
program:-
Emulation of 92K single, 133K Dual and 184K double
density drives.
Hard disk emulations of 1, 5, 10 or 16Mbyte disks with
SpartaDos or MyDos.
Up to 8 simultaneous drives in any combination of sizes.
Print through from your ATARI to an attached PC printer,
the PC screen or a PC file.
Write protect (via MSDOS) of your disk images.
Configuration files to allow you to start up with your
preferred options preset.
Ability to load, unload or interchange disk files while
the program is running.
The ability to automatically set your SpartaDos clock
from the PC clock.
File transfer from MSDOS to ATARI format and vice versa.
If you have access to a PC with free disk space then this
program will provide an alternative to using real 810, 1050 or
hard disk drives without loss of compatibility with anything
other than copy protected disks.
2. Installation.
The software is distributed in MSDOS format and is
contained within the self extracting archive file HDINST.EXE.
To install the program copy the HDINST.EXE file into your
chosen PC directory and simply type HDINST. The files
contained within HDINST.EXE will now be extracted
automatically and should appear as:-
HDEMUL.EXE The main program
HDEMUL.UG This user guide
MYDOS.DSK The MYDOS 4.50 disk image
The HDINST.EXE archive file may now be removed from the
working directory.
3. Starting the Emulator.
The emulator can start up in 3 ways depending on whether
any configuration files exist in the working directory.
Configuration files have the file extension .CFG and are used
to preset the emulators' working parameters. Details of how to
create a configuration file and which parameters it affects
are in section 6. When you start the emulator for the first
time there will be no configuration files available.
4
3.1 No configuration files.
Type HDEMUL in the working directory and the
emulator will load and start. The main menu screen will
appear followed by a prompt at the bottom of the screen
asking you to enter the COM (serial) port number that you
wish to use. Only numbers between 1 and 4 or M will be
accepted. Enter the number appropriate to the port to
which your SIO2PC hardware is attached. If you have a non
standard PC whose serial port address does not correspond
to the normal values (COM1=03F8h 2=02F8h 3=03E8h 4=02E8h)
then type M.
Typing 1 to 4 will cause the program to initialise
the appropriate port and enter the main program. Typing M
will bring up a second prompt asking for the four digit
hexadecimal value of your port address. All 4 digits are
required, so use leading zeros if necessary. Only the
values 1 to 9 and A to F will be accepted. After the
fourth digit the program will initialise the port and
enter the main program.
3.2 Default configuration file exists.
When the emulator is started by typing HDEMUL on its
own it first searches the working directory for a default
configuration file called HDEMUL.CFG. ( See section 6 for
instructions on how to create such a file). The program
will start up, initialise the COM port,load any
identified disk files and then move to the main program
loop automatically if the default file is found. It will
behave as in 3.1 if no file is found.
3.3 Named configuration file.
Configuration files can be created with any valid
filename in order to allow you to start the program with
a variety of parameters (see section 6). To use a
different configuration file simply type HDEMUL FILENAME
and the program will behave as in 3.2 but will use the
FILENAME.CFG parameters.
With this facility you may create a number of .CFG
files for different purposes. For example you may create
one which loads your word processor into D1, your text
files into D2 and sets the COM port. If you then name
this WP.CFG you can type HDEMUL WP and the emulator will
set itself up ready to start your word processing session
without any intervention from yourself.
4. Screen Display.
The screen may be divided into 4 areas. The top part
contains all of the main menu options (see section 5).
The next part contains the drive numbers. When a file is
loaded into a drive the filename, size and density will
be displayed against the drive number. In addition the
letters RO will appear if the file is write protected.
5
The apparently empty area below the drive numbers is used
for two purposes. All prompts to which you must respond
will appear in this area and any error messages detected
within the emulator program will also be shown here. The
error messages will display for a time between 1 and 59
seconds before disappearing. The default is 1 second but
this may be changed from the configuration menu (see
section 6).
Note that these errors refer to the operation of the PC
program and do not relate to the ATARI or the SIO bus.
Typically they will be cheerful little missives like disk
full or invalid filename and will occur when you least
want them.
The final area is the line status display. This tells you
what the ATARI has just sent to the PC in its command
buffer. The first entry is the command number (in hex and
as an ASCII character), the second is the device identity
to which it refers, the third and fourth are the values
of AUX2 and AUX1 respectively and finally the command
line status (high or low) is displayed. Device identity
and auxiliary values are displayed in hex.
The purpose of the status display is to keep you abreast
of the SIO bus activity. Note that AUX2 deliberately
appears before AUX1. This is simply because these fields
are predominately used as sector identities with AUX2
containing the most significant part. By displaying AUX2
first you can determine the sector address without having
to make a mental juxtaposition.
Typically you will see
Command:52 (R) Device:31 Aux2: 01 Aux1:68 Command
Line: H
which means the ATARI is trying to read from drive 1,
sector 168h. The Command line actually flickers very
rapidly between H and L. In practice the display will be
predominately H but will flick onto L momentarily in time
with the command frames. If it ever shows L consistently
then you have lost contact with the ATARI bus.
5. The Main Menu.
The main menu options are available at any time once
the COM port has been initialised. They should NOT be
used while an SIO data transfer is in progress. The main
menu routines run independently of the SIO handler and
the program will stop polling the SIO line while the menu
options are being actioned which will result in loss of
data.
Many of the options require additional input. If you
wish to abandon an action during the input sequence then
press ESCAPE to return you to the main menu and cancel
the action.
5.1 F - Create Floppy Disk.
Each pseudo floppy disk that you create is actually
an MSDOS file which will be 16 bytes longer than the
capacity of the disk that you specify. The first 16 bytes
contain header information for the emulator to use and is
6
normally transparent to you.
To create a floppy disk choose the F option. You
will then be prompted for the drive number that you wish
to assign to the disk. Enter a number between 1 and 8. If
you choose a drive which already has a disk assigned to
it then the new disk will replace the existing one
without damage to the original.
The emulator then asks you to choose 1 of 3 sizes
for the disk. Type 1 for a 92K single density, 2 for a
133K dual density or 3 for a 184K double density disk.
Next the program will ask you to assign a name to
the disk. As this name will be the MSDOS filename for the
disk image it is necessary to obey the normal MSDOS rules
in choosing the name. It is also very sensible to give it
a meaningful name and to use a standard extension (.DSK
for example) such that you can readily distinguish the
disks in your directory listings. Complete your filename
with a carriage return and the program will set up the
MSDOS file, clear all the entries in it to zero (the
progress of which will be displayed on a thermometer) and
load the file into the chosen disk drive.
At this stage you MUST use your ATARI based DOS to
format the disk as if you had just put a new disk into a
physical drive. The actual ATARI format request will be
ignored by the emulator but your ATARI DOS will then go
on to build a directory structure on the disk without
which it will be unusable. Take care to match the format
request to the size of the floppy disk or you will
encounter problems.
5.2 H - Create Hard Disk.
To create a hard disk image type H. The program will
ask which drive you wish to assign to the disk and then
prompt you for the size of the disk. Choose 1 for a 1
Mbyte disk, 2 for 5Mbytes, 3 for 10Mbytes and 4 for 16
Megabytes. Remember that the disk image will be created
at full size so make sure that you have enough room on
your PC disk for the new file.
The program will then prompt for the disk file name
which must obey the normal MSDOS rules for file names.
Once this is entered the program will create the MSDOS
file and clear the entries to zero. A thermometer will
display the progress of the clearing operation which will
take quite a long time, especially for a 16MByte disk. Be
patient, as long as the thermometer is rising you can be
sure that the program has not stalled.
Once the file has been initialised it MUST have a
directory structure written to it. This is achieved by
using either the format or build directory command of
your ATARI DOS. Obviously you must be using a DOS which
will support hard disks (ie not ATARI DOS 2.5). The
method for SpartaDos X, SpartaDOS 3.2 and MYDOS is
described below.
5.2.1 SpartaDos X.
Users of the SpartaDos X cartridge should type
FORMAT and wait for the fancy box to appear. Identify the
disk unit number for the hard drive and you should see,
7
for a 1 Meg disk, 4096 sectors, 1048576 Bytes and Format
n/a appear in the box. Obviously for other sizes of disk
the values will vary. Set the Volume name if desired and
then press B to Build Directory and you will get the
message:
"Unit is NOT a floppy disk. Are you sure?".
Press Y for Yes and you will get the message:
"Caution. Destroys Old Data. Are You sure?"
Press Y again and SpartaDos will then write out the
appropriate sectors to make the disk useable.
5.2.2 SpartaDos 3.2
SpartaDos 3.2 users should run the HDINIT.COM program.
The program will prompt with:
"Hard Drive to Format (3 or 4)?".
If your drive is neither 3 nor 4 then use the eXchange
disk option on the emulator so that it is. Respond with
the appropriate drive number and the program will ask:
"Volume Name?".
Type in the volume name and you will see:
"Initialize - Are you sure?".
Respond with Y and SpartaDos will initialize the disk and
build the directory structure for you.
5.2.3 MyDos 4.50.
This method probably works with other versions of MYDOS
which support high capacity drives but I can only verify
it for 4.50.
Choose O - Change Configuration from the menu and follow
this sequence:
Drive No. or return? type in drive number
Remove Drive? type N for no.
Is Drive Configurable? type Y for yes
High Capacity Drive? type Y for yes
Drive Size (sectors) type 4096 for 1 MByte
20480 for 5 Mbyte
40960 for 10 MByte
65535 for 16MByte
Now choose I- Initialize Disk from the menu, choose the
appropriate drive and type Y to format and it should all
happen for you.
5.3 L - Load Disk
The load disk option allows you to mount your MSDOS
file images on one of the 8 drives. The protocol is
simple, specify the drive number and MSDOS filename when
asked. Note that the file name can contain a full path
specification if you want to load a file from other than
the current directory. You may load files from any PC
drive, including floppies.
If the file specified is not an HDEMUL or SIO2PC
disk file then an error message will be displayed and the
load aborted. If the file does not exist you will be re-
prompted for the file name. Escape will return you to the
main menu from the filename prompt.
8
5.4 U - Unload Disk.
Unload disk will prompt you for a drive number and
then close the associated MSDOS file. The drive display
will be cleared and the emulator will no longer respond
to commands for that drive.
5.5 X - Exchange Disk.
Typing X for exchange disk will cause the emulator
to prompt you separately for the two drive numbers on
which the disks that you want swapped are mounted. The
emulator will close both files and re-open them on the
designated drives. It is permissible to swap with an
empty drive or even swap two empty drives if you have got
time to waste.
5.6 R - Make Disk Read Only.
With all these disk drives floating about it is very
easy to write to the wrong drive from time to time. To
protect your program disks from being over-written select
option R from the menu. This option will prompt you for a
drive number and then make the MSDOS file currently
loaded on that drive read only. This will permanently
change the MSDOS file attribute and the file will remain
read-only until you explicitly change it. The file will
display the letters RO after it whenever it is loaded to
remind you that it is read only.
The action is the same as executing the MSDOS command:
ATTRIB +R filename
5.7 W - Enable Write to disk.
Option W provides you with a means of reversing the
effect of option R. Writing to the MSDOS file is enabled
and the file attributes are permanently changed.
The action is the same as the MSDOS command:
ATTRIB -R filename
5.8 S - Set Port Number.
Option S allows you to change the serial port
address during a session. You will be prompted to enter
the new COM port number (between 1 and 4) or type M if
you have a non-standard PC and wish to set the port
address manually. Typing 1 to 4 will cause the new port
to be initialised immediately and return you to the main
menu. Typing M will bring up a second prompt inviting you
to type in the 4 digit hexadecimal address of the COM
port. Only the digits 1 to 9 or A to F will be accepted.
You must type all 4 digits so use leading zeroes if
necessary. On the fourth digit the program will
initialise the address and return to the main menu.
5.9 D - Display directory.
The directory option is provided to allow you to
look at the contents of the PC disk(s). The default
filespec is preset in the emulator and is equivalent to
9
current directory:*.*. That is you will see all of the
files in the current directory. Having pressed D a screen
will appear that tells you what the current filespec is
set to and inviting you to accept it with a carriage
return or type in a new filespec. Once you have changed
or accepted the filespec the screen will be replaced by a
standard MSDOS directory listing satisfying that
filespec. Press any key to return to the main menu once
you have finished with the directory listing.
The default filespec is one of the items which may
be changed from the configuration file (see section 6).
By adopting a standard convention for disk file extension
naming (filename.DSK for example) and setting the
filespec to only report files conforming to that
extension ( *.DSK in this example) you can reduce the
clutter on the screen and see only the available disk
files.
5.10 Q - Quit Program.
Pretty well self explanatory. Note that all files,
including any print-through file, will be automatically
closed when you quit. It is unnecessary to unload your
disks before quitting. Always try to quit from the
program rather than exit by any other means in order to
maintain the integrity of your file data.
5.11 T - Toggle Line Status Display.
At the bottom of the screen is the line status
display. It shows the current (or last) command
processed, the device ID for that command, the values of
AUX2 and AUX1 in that command and the status of the
command line (high or low). The information is provided
to give you an insight into what is happening on the SIO
bus.
If you do not wish to see this display or your PC is
having trouble keeping up with the ATARI then press T to
toggle the display off. Subsequent presses of T will
toggle the display on or off.
5.12 C - Create/Amend Configuration.
Use this option to create or change the .CFG
configuration files. For details see section 6.
5.13 P - Print Through Mode.
The emulator will accept commands for the ATARI P:
device (40h) if you enable the print through mode by
pressing P. There are a number of questions to be
answered in order to set the print through mode. First it
will ask whether you want to print to the PC printer port
(P), the screen (S) or a disk file (F).
If you choose to print to a file then you will be
asked for the MSDOS filename. This must follow the normal
MSDOS naming rules. If the file already exists you will
be asked whether you wish to overwrite it (O), in which
case the file will be erased and then re-created,
reselect the filename (R) which will take you back to the
filename prompt to choose a different name, or append (A)
10
which will add the print output to the end of the
existing file.
Whatever the choice the question "DOS text
conversion required" will then appear. If you select Y
for yes then all the ATARI EOL character (9Bh) will be
converted to the DOS carriage return, line feed sequence
(0Dh,0Ah). In addition ATARI tabs (7Fh) will be changed
to DOS tabs (09h) and the high bit which the ATARI uses
for inverse characters will be stripped off. Other
control codes will be allowed through and can have funny
effects so be prepared.
Selecting N for no at the conversion prompt causes
the emulator to pass everything straight through to the
chosen destination. It is unlikely that you will have any
success in displaying or printing this output in the
MSDOS environment but it is useful for copying machine
code files to an MSDOS file.
There are two further points to bear in mind when
printing to the PC. The P for printer option will spool
data to LPT1: so make sure that is where your printer is
sitting. The control Z character (1Ah or 26 decimal) is
used by the ATARI as a graphics character which is very
useful as the bottom left hand corner of a box. In the
MSDOS world it means end of file. Even with DOS text
conversion turned on the control Z will appear in the
MSDOS file. Subsequent attempts to use MSDOS commands
like type, copy or print will stop when MSDOS encounters
the control Z. The rest of the file will be on disk but
you will have trouble finding it with an MSDOS command.
With print-through enabled the main menu display
will change to:
Printing to (destination). Text conversion on (or
off).
where destination is either printer, screen or the
filename.
All print output will be directed to that
destination until you press P again. The second P will
close the destination device and disable the print
through mode.
While printing to the screen the display will remain
on the printer output until you press any PC key. The
main menu will then be restored. If you press a valid
option key that option will be actioned. If this was not
your intention then escape will cancel most of them.
Hitting the space bar is probably the best way to return
to the main menu without disruption, or use P if you also
want to close the printer stream.
6. Configuration Files.
Configuration files allow the pre-setting of many of the
parameters which the emulator uses when it starts up.
When a configuration file is used it is unnecessary to
set the port number or load any disk files into drives.
If you create a configuration files with the name of
HDEMUL.CFG the emulator will find it and use the values
within it whenever HDEMUL is typed to start the program.
Creating lots of configuration files means you can start
the emulator with the set of disk files most appropriate
11
to the task at hand. For example you might create a
WP.CFG file for word processing, a MAC65.CFG file for
assembler language programming with the MAC65 cartridge
or a MYDOS45.CFG or SDOS32.CFG to enable you to boot
under different DOS versions. Starting the emulator with
the command HDEMUL MAC65 will automatically load your
drives with all the files specified within the .CFG file.
This can then taken one stage further by creating a
MAC65.BAT file containing the HDEMUL MAC65 command which
will get the whole thing going just by typing MAC65.
In addition it is possible to fine tune some of the time
out values, set the default directory filespec and
determine whether the status line will be displayed.
6.1 Creating a Configuration File.
Configuration files can be created by selecting
option 'C' from the main menu. This takes you to a
new menu screen with the configuration options
displayed. Use the cursor up and down keys to move
through the options and press the return key when
you get to one that you want to alter.
The display will initially show the current options
in force on the emulator.
6.1.1 Set port address.
Selecting this entry brings up the familiar prompt
to select the port address (1-4) or M for manual.
Selecting 1 to 4 will immediately insert the port
number into the menu and return you to the menu
level. M will cause the program to prompt for a 4
digit hexadecimal address which you should enter.
Only digits 1 to 9 and A to F will be accepted. You
must enter all 4 digits so use leading zeroes if
necessary.
6.1.2 Load drives D1: - D8:.
Selecting any of the lines from D1: to D8: will
bring up a prompt to enter the disk filename that
you want loaded onto the drive. Type in the file
name and press Return. If the file does not exist
the program will prompt with:
File does not exist Continue anyway?
Type Y if you intend to create the file later or N
if you have made a mistake.
The program does not check that the specified file
is a valid disk file. If it is invalid the emulator
will simply error the load when it is run with this
configuration file and continue without loading
anything. Similarly if you use a non-existent
filename the emulator will ignore the entry next
time it is run.
To delete a file from the list select the drive and
press return at the filename prompt.
6.1.3 Default Directory Specification.
When you select the D option from the main menu the
emulator will display a file specification which it
12
will use in the directory search. To alter the
default value select this option and type the new
file spec when prompted.
6.1.4 Time-outs.
A number of time-outs exist within the emulator,
most of which default to zero. The time-outs are
used to at stages of the command sequence when it is
possible for the PC to respond to the ATARI so
quickly that the ATARI is not ready to accept the
response. Various constant values are built in to
the emulator already and the values given on the
configuration menu are added to the in-built values
to give a crude tuning facility if you happen to
have a 'slow' ATARI.
To appreciate the significance of the time-outs let
us use the examples of the read sector and write
sector commands from the ATARI:
1) Command line goes low and Read command is
transmitted to the emulator.
2) Command line goes high and the emulator responds
with ACK. No time-out is used within the emulator
because this action is tied to the raising of the
command line.
3) The ATARI now waits. The emulator prepares the
sector data. Applies the TIME TO COMPLETE time-out
and then sends COMPLETE to the ATARI.
4) The ATARI still waits. The emulator applies the
SEND DATA TIMEOUT and then sends the sector
contents.
The sequence is now finished.
Similarly on a Write sector command:
1) The ATARI lowers the Command line and sends the
Write Sector command.
2) The ATARI raises the command line and the
emulator respond with ACK using no timeout.
3) The ATARI sends the sector data and the PC
applies the TIME TO ACK timeout before sending ACK
again.
4) The emulator writes the sector and then applies
the TIME TO COMPLETE timeout before sending COMPLETE
to the ATARI.
The sequence is now finished.
The TXDATA TIMEOUT is applied between each byte of
transmitted data on every PC to ATARI message. The
effect of lengthening this is to slow down the
message transmission rate by introducing pauses
between each byte. The bit rate remains, of course,
at 19.2K.
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Because of the way that the low level PC timer works
the values entered for the protocol time-outs
actually give you 85*value microseconds of delay ie.
1 gives you 85 microseconds, 2 gives you 170
microseconds and so on. Given that the values that
you will be entering are likely to be guesswork
anyway I doubt that this will represent a serious
impediment.
The ERROR DISPLAY TIMEOUT determines how long
emulator error messages remain on the screen. The
value is in seconds and may be set between 1 and 59.
To set any timeout, highlight it with the cursor
up/down keys, select it with return and type in the
new value when prompted.
6.1.4 Display Status Line.
You may predetermine whether the status line is
displayed by setting this value to Y for yes it is
displayed or N for no it is not. It is preset to
Yes.
6.1.5 Loading an existing configuration file.
If you want to change the emulator settings from a
configuration file without restarting the program
or, if a configuration file already exists which is
similar to the one that you wish to create, you can
load an existing file by typing L. You will be
prompted for the new filename which will then be
loaded and its parameters will replace those on
display.
If you have changed anything on the displayed menu
prior to loading the file you will be asked if you
want to save your changes before the load over-
writes them.
The new parameters will not come into force until
you exit the configuration menu.
6.1.6 Saving your changes.
You may save your configuration file at any time by
pressing S. You will then be prompted for the save
filename. There is no need to add any extension to
the filename, but if you do then make sure it is
.CFG or you may forget its purpose. Remember that a
file saved as HDEMUL.CFG will form the default load
file provided it exists in the same directory as the
emulator program.
After saving the file you will be returned to the
configuration menu.
6.1.7 Exit.
It is necessary to type E for exit in order to
return to the main menu. If you have made no changes
since you entered the configuration menu, loaded a
file or last saved then you will be given three
choices:
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1) Exit and use new parameters. Use this if you wish
to invoke the configuration values which are
currently displayed on the menu.
2) Exit. Returns to the emulator which will use the
values it had before you entered the configuration
menu.
3) Return to configuration menu. Cancels the exit
routine.
If you have unsaved changes on the screen when you
exit there are 4 actions you may take:
1) Lose changes and exit. Choose this if you want to
abandon your edits and return to the emulator to use
the original values.
2) Save changes and exit. Use this if you want to
save your edits but do not wish to use the new
values when you return to the emulator.
3) Save changes, exit and use new parameters. Use
this if you wish to save the edits and load the new
values into the emulator for immediate use.
4) Return to configuration menu. This option cancels
the exit routine.
7. Time and Date Support.
HDEMUL provides a special interface which allows a
program running on the ATARI to get the time of day and
the date from the PC clock. The MYDOS450.DSK disk file
contains a program called SDTIM.COM which may be run
under SpartaDos to set the time and date for SpartaDos.
By placing it in your start-up file it should provide an
alternative to the RTIME8 cartridge.
The details of the time/date interface follow for users
who wish to write their own programs.
Command from ATARI to PC:
Command=52h (Read), Device=3Fh, AUX1=0, AUX2=0.
This will return a 128 byte buffer with the following
contents:
Byte 0 Year (hundreds) e.g. 19
Byte 1 Year (tens) e.g. 92
Byte 2 Month (1-12) e.g. 1 = January.
Byte 3 Day (1-31)
Byte 4 Day (0=Sunday, e.g. 3=Wednesday
1=Monday)
Byte 5 Hours (0-23)
Byte 6 Minutes (0-59)
Byte 7 Seconds (0-59)
Byte 8 Hundredths of seconds (0-99)
Byte 9-127 Unused.
The file SDTIM.TXT on disk MYDOS.DSK is the source for
SDTIM.COM and will give you an example of how the
interface is used.
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8.File Transfer Utilities.
To enable the transfer of files between the MSDOS format
and ATARI Dos format and vice versa a program called
PCTFR.COM has been provided on the disk MYDOS.DSK. The
program will run under any type of DOS so that you are
not restricted in your choice of ATARI format. The
program uses a special file transfer protocol built into
the emulator and thus can only be used in conjunction
with HDEMUL.
The PCTFR.COM program was written with PL65 from NOAHSOFT
and uses their run time routines.
8.1 The PCTFR program.
Run the PCTFR.COM program from the run binary file
option of you favourite ATARI DOS (option L for DOS 2.5).
A menu will be displayed on your ATARI screen with the
following options.
A) Transfer file from PC
B) Transfer file to PC
C) Text Conversion
D) List Atari Directory
E) Exit to DOS
Before you get stuck into transferring files you need to
consider whether you require DOS text conversion. Without
it the file will be transferred as is. This is the
default and should be used for all binary file transfers
(i.e. programs that run on the ATARI rather than text
files).
With text conversion turned on the following
substitutions will be made:
Transferring a file from the PC to the ATARI -
MSDOS CR LF sequences will be converted to
Atari EOL.
Transferring a file from the ATARI to the PC -
ATARI EOL converted to CR LF.
ATARI TAB (127) becomes DOS TAB (09)
ATARI control codes (ATASCII values < 31)
become spaces (32)
ATASCII inverse characters (>127) have the high
bit stripped.
This is a more severe translation than using the emulator
Print to file option (with DOS text conversion) since all
the Atari control characters are stripped out and
replaced by spaces.
To toggle the text translation option press C. The
current status is denoted by Yes its on or No its not on
after the menu entry.
The rest of the program is hopefully self evident. Select
A to transfer a file from the PC to the ATARI and give
both filenames when asked. You may include a drive spec
and path name in the PC filename if the file is not in
the same directory as HDEMUL (eg
A:\ATARI\DOWNLOAD\NEWGAME.ARC). The file will transfer
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and report success or failure as appropriate.
Option B will move a file from the ATARI to the PC. Again
give both the ATARI and PC filenames when asked and sit
back and hope while the data is transferred.
Option D prompts you for an ATARI drive number and then
gives you a directory listing of that drive. If you want
to know what is on the PC use the emulator option D. Same
command, different keyboard.
Option E will return you to DOS.
The most probable error messages will be translated to
English and the rest will display the ATARI DOS error
code for you to look up and correct.
Transfers may be made from any combination of physical
and emulated drives provided all transactions are via
HDEMUL.
Note that files will be overwritten without warning if
you use an existing filename.
The ATARI escape key will abort a transfer tidily if you
change your mind after the process has started. I have
not disabled break or reset but it would not be advisable
to press either during a transfer unless you really want
some practice unscrambling your disk.
8.2 The File Transfer Interface.
A series of special commands have been included in the
emulator to allow the file transfer mechanism to work.
For the technically minded these, and the sequence which
they must follow, are described below. Skip this section
unless you have intentions to write your own file
transfer program.
All commands are sent with Device ID = 3Ah. This is what
tells the emulator that it is a file transfer command.
The commands are:
Command: Status Aux1: 'I' Aux2: 'R'
Initiates a read from PC sequence. PC transfer state must
be idle.
Response: Ack if OK otherwise Nack or Err.
Command: Status Aux1: 'I' Aux2: 'W'
Initiates a write to PC sequence. PC transfer state must
be idle.
Response: Ack if OK otherwise Nack or Err.
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Command: Status Aux1: 'L' Aux2: 'R'
Request for PC file length. Valid only after a "Write
Filename" in a read sequence.
Response: 4 byte status response containing 32 bit integer
file length. Bytes 0 & 1 are most significant, bytes 2 & 3
least significant.
Command: Status Aux1: 'A' Aux2: -
Aborts transfer sequence, closes file and returns PC to
idle state. Valid at anytime.
Response: Ack if OK. Nack or Err otherwise.
Command: Status Aux1: '?' Aux2: -
Request for PC to send last error code.
Response: 4 byte status response with error code in byte 0.
Valid codes are: 250 File read failure.
251 Emulator transfer sequence error.
252 File write failure.
253 Unable to open file.
254 Incoming message not recognised.
255 General error (i.e failed to
categorise failure)
Command: Write Aux1: 'F' Aux2: -
Followed by a 256 byte data buffer.
Transmits the filename from or to which data is to be
read or written so that the PC can open the file. The
file name must obey normal MSDOS rules and must be
terminated with an ATARI EOL (155) character. If the file
is to be written to then any existing file of the same
name will be lost. The file name may include a full
directory and path specification.
Valid only after an initiate message.
Response: Ack, Nack or Err.
Command: Write Aux1: 'D' Aux2: Byte count (0=256 bytes)
Followed by a 256 byte buffer containing the number of
valid bytes specified in Aux2.
Data to be written to the PC file. Valid only after the
filename has been received. Note that a partial buffer
full of data does not lead to termination of the
transfer. This must be done explicitly with a Status
Abort message.
Response: Ack, Nack or Err.
Command: Read Aux1: - Aux2: -
Request for next buffer full of file data. The emulator
will return 256 bytes of data even if the end of file is
reached before the buffer is filled. It is the ATARIs'
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responsibility to keep track of the valid byte count. The
transfer will not end when the end of file is reached. It
must be explicitly terminated with a Status Abort
message.
Valid in a read sequence after Write Filename.
Response: Ack followed by a 256 byte data buffer, Nack or Err.
9.Problems
Obviously there are many different PC clones available
and a wide variety of hardware set-ups available which
makes it difficult to guarantee that the emulator will
always work. If you experience problems here are a few
suggestions which might help. If none of these work then
try and contact me on the City BBS (021-321-1610 Username
Peter). Please try to describe ALL of the events which
led to the failure as the sequence may well be important.
HDEMUL fails to run on the PC:
Remove any TSR programs and try again. Check that
the EXE program is not corrupt. Re-install it if in
doubt.
HDEMUL starts but keyboard does not respond:
This sometimes happens if the PC generates a
spurious character on the COM port when it starts
up. The emulator thinks it is receiving a command
and loops waiting for the rest of the command frame.
Re-booting the PC should clear it. If your ATARI is
attached then turn it on. The ATARI boot sequence
will then send commands to the PC which will unblock
the tubes.
The ATARI does not boot when turned on:
Have a look at the emulator status line. If you have
contact with the ATARI you should see the display
changing as the ATARI boots. If the display is empty
then check the COM port setting. If this is OK then
suspect your SIO2PC hardware. Try running the SIO2PC
programs if you have them. If this works then there
must be a major emulator fault. If SIO2PC does not
work either then you have a hardware problem.
ATARI hangs and then reports device not available:
During the 'hang' period try getting the PC to
respond to a Directory command. If the PC responds
then it obviously thinks that it has completed the
ATARI command and is actually hanging around waiting
for some action. The most common cause of this
problem is that the PC has serviced the command and
responded before the ATARI was ready to process the
response. Try slugging the emulator response by
playing with the time-outs in the configuration
menu. The Time to Complete value is a good one to
have a go at. Be generous and use high values (in
the thousands) until you have proved the problem and
then come back down again to a more sensible value
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when you are confident that you have located the
problem.
If the PC does not respond to your key press then it
is waiting for data from the ATARI to complete the
command sequence. This may be due to a poor
connection causing line noise, a very slow PC which
is failing to keep up with the incoming data or poor
programming on my part. Try thumping the hardware
and then the programmer.
Command values are unusual when used with an enhanced
drive.
This is quite normal and represents the enhanced
command set of the drive. Note also that the status
line will not display sector values when used in
conjunction with an ultra-speed SIO set-up.
General
If your PC is caching disk writes then you may
experience some problems. The problems are not
caused by the cache itself but by the fact that the
PC nips off to empty the cache onto the physical
disk from time to time. While it is doing this the
scan loop of the emulator is interrupted and it is
possible to loose a command line transition or data.
Normally the ATARI command repeat sequence will
take care of this but it is possible that, with a
very slow disk, the problem could become more
serious. If you have problems which occur at about
the same frequency as the hard disk drive light
flickers then try disabling the caching. Read
caching should not cause any problems and will
probably be beneficial.
The use of a disk drive on the SIO chain with the
same drive number as an active emulated drive will
cause unpredictable results. Unload the drive in
HDEMUL or turn off the physical drive.
If the PC is turned on and in use but has not run
HDEMUL or SIO2PC since it was last booted then there
will be a problem accessing devices on the ATARI SIO
line. The PC port must be initialised before the
ATARI kit will work. Either run HDEMUL briefly or
unplug the SIO2PC hardware from the SIO chain to
regain control of the ATARI. I have fitted a little
switch to my SIO2PC hardware so that I can turn it
off and avoid this situation.
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