Re: XIEEE

From: William Levak (wlevak_at_cyberspace.org)
Date: 2000-10-20 05:28:08

On Thu, 19 Oct 100 g.j.p.a.a.baltissen@kader.hobby.nl wrote:

> The problem starts at the point the CBM starts to send bytes again (for 
> whatever reason). And my program is programmed for that way; it quits with an 
> error because it sees that the CBM refuses to accept data. The CBM quits with 
> an error because for the same reason.

The three zero bytes indicate the end of the Basic program, but do not
necessarily indicate the end of the load.  A Basic program can have a
machine language part attached to the end.  The load program simply stores 
these at the end of the Basic program an increments the end-of-program counter.

There is an end of transmission signal sent from the drive, apart from the
IEEE protocol, that indicates that loading has terminated.  I am not
familiar with what that actually is.....

I have just looked this up in "Compute's VIC-20 and Commodore 64 Tool Kit:
Kernal".

The load routine continues to receive bytes and store them in memory until
it receices the EOI status word, 90.  It says that any further bytes sent
are discarded and the UNTALK command is then sent from the computer.  This
forces the drive to send it's last byte, and then the computer sends
LISTEN and then CLOSE secondary address $E0.

   



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