Re: [cc65] Why does this work in 128 mode but not 64 mode?

From: Spiro Trikaliotis <ml-cc651trikaliotis.net>
Date: 2010-05-03 21:01:42
Hello,

* On Sun, May 02, 2010 at 10:48:59PM +0200 Kajtár Zsolt wrote:

> > The only workaround I can think of: When doing an open, and there is no
> > filename, issue a LISTEN/UNLISTEN sequence. If the LISTEN fails, then
> > there is no device attached. Then, let the OPEN fail.
> 
> No IEC specific stuff please. Classic check is a CHKOUT/CLRCHN (which is
> almost the LISTEN/UNLISTEN as above for IEC), as the CHKOUT will fail on
> device not present.

Ok, I should have been more specific. A LISTEN/UNLISTEN sequence (or any
other access to the IEC bus *other* *than* TALK/UNTALK) should be
executed. Your proposal is better than mine in that it does not use the
IEC routines, that's right.

> Other workaround as an OPEN time check (which I already
> proposed):

Agreed, this would also work.

 
> > Need the workaround:
> > - VIC20
> > - C64
> 
> Basically both are running the same KERNAL/BASIC with minor hardware related
> differences. (and one or two bug fixes in the C64 version)

I know. I generated a ca65 file (or, more precisely, multiple of them)
in order to be able to assemble all "standard" VIC20 or C64 BASIC +
KERNALS out of it. I know the differences between the two very good. ;)

 
> > - PET with BASIC 4.0, KERNAL 4.0
> >   (but: Does not return with "DEVICE NOT PRESENT", instead status bit 1
> >   (timeout on read) is set
> 
> That's IEEE-488, no wonder it's different. The OPEN/CLOSE workaround will not
> work on this.

Well, it could have been that Commodore took over the problem from the
IEEE world to the IEC world. In fact, it seems it was a new error
introduced in VIC20.

Even more weird: cbm4linux had this problem, too. When I ported it to
cbm4win, I fixed this problem for Windows. However, it seems I did not
recognise its importance, as I left the Linux version untouched.

 
> ps.: I'm to posting code/patches now, as it's a waste of time most likely.

Uz did not mention yet if he would consider such a patch. If yes, I
could generate one. (Or did you want to say that you want to post one?)

Regards,
Spiro.

-- 
Spiro R. Trikaliotis                              http://opencbm.sf.net/
http://www.trikaliotis.net/                     http://www.viceteam.org/
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Received on Mon May 3 21:01:57 2010

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