1. Use the IEEE card only from within an Applesoft program. If you try to use
it in command mode, a SYNTAX ERROR will result, since the Applesoft
prompt "]" will be sent to the interface. If you do not reset the I/O at the
end of your program, a "CMD ERR" will result.
2. Issue the command "SC1" as one of the first commands in any new program.
This command will cause the IEEE commands to be echoed to the screen for
easier debugging. When the device works properly, the "SC1" can then be
removed.
3. Ascertain whether the IEEE device you're using requires the REMOTE ENABLE
command before it will accept anything you send it. (Many IEEE devices do
require this command.) If the device requires the command and does not
receive it, the device will not be enabled: it will handshake properly but
won't recognize its address on the bus, and will therefore return a BUS
ERROR the next time it's accessed. In some cases, the "RA" command can be
used to turn on all remote devices on the bus; likewise, the "RM address
list" command can sometimes be used to enable selected devices.
4. Understand the convention for listener and talker addresses. All devices on
the bus have a device number in the range of $00 to $1E. If you want the
device to act as a listener, use the address range $20 to $3E--that is, add
$20 to the device number. If you want the device to act as a talker, use $40
to $5E--that is, add $40 to the device number. For example: If an HP 3438A
has a device number of 3 and if you want it to be a listener you must
use address $23. From the keyboard, $23 is a , so you could use (for
example) PRINT "TG ". If the device is to be a talker, you must use address
$43, which is an upper case C from the keyboard; an appropriate command to
use would be PRINT "RDC".
Article Change History:
14 Nov 1996 - Reviewed for technical accuracy, revised formatting.