Re: LOAD command (Was: Disk drive questions)

From: Marko Mäkelä (
Date: 2002-11-18 20:16:30

On Mon, Nov 18, 2002 at 02:08:07PM +0200, Marko Mäkelä wrote:
> If the IBSOUT vector points to cassette buffer #1 while the header is
> located in cassette buffer #2, the loader won't be started.

Hmm, there does not appear to be any IBSOUT vector on the PET 8032, but there
is a vector ($eb) for printing to screen.  Maybe I can use the vector ($e9)
for determining the original value of the ($eb) vector.  Hmm, the BASIC 2.x
series editor ROMs (901447-24 and 901474-01) do not have a similar jump table
or the jump vector - perhaps using the IRQ vector is the easiest solution on
the PET.

Tonight, I successfully ported the loader to the C128 and the plus/4.  On
the plus/4, I noticed that the OS stops loading already when seeing the
high-to-low transition of the last bit of the checksum byte.  It does not
wait for the terminating medium pulse or the sync pulses.  On the
VIC/C64/C128, only the terminating sync pulse stream can/must be omitted.


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