title vtio bug (NitrOS9 EOU beta 5) leax <CoGrf,pcr
user strick
ip 75.144.20.99
vol 1
lock ********

In Beta5 of http://www.lcurtisboyle.com/nitros9/nitros9.html :

In the /sourcecode/asm/nitros9/scf/ directory of 68SDC.VHD
there is a module vtio_beta5

The file vtio.listing has checksum 32DC40
but when I compile it with "lwasm" I get a checksum of 4BE2D6

When I boot the EOU beta 5 distribution (with my gomar emulator),
it uses a vtio module with the checksum 32DC40.

I did some hacking to compare the modules, and the difference
is in this line


/tt &nbsp;   leax  <CoGrf,pcr point to CoGrf name


In vtio.listing that is assembled as

/tt &nbsp;   0921 308CDC

but in my assembly it comes out as

/tt &nbsp;   0921 308CE3

Doing the bits, mine is right, and the vtio.listing is wrong.

Why?  Well before I could assemble it with lwasm, I had to fix
an error that "CoGrf" was redefined.   So in my version,
I had renamed the label "CoGrfName".

I assume the old Microware assembler is using the original
definition rather than the local definition.

And I think the hack comment indicates this bug was causing problems.

/section EXCERPT FROM vtio.listing:

/box(
/pre(
01557   0900 35E2                puls  pc,u,y,a   restore regs & return
01558
01559   0902 436F5769   CoWin    fcs   /CoWin/
01560   0907 436F4772   CoGrf    fcs   /CoGrf/    ++
01561        *CC3GfxInt fcs   /CC3GfxInt/ ++
01562
01563        *
01564        * Try CoWin
01565        *
01566   090C 3460       FindWind pshs  u,y        preserve regs
01567   090E 4F                  clra             set window type
01568   090F A7C81D              sta   <V.WinType,u
01569   0912 308CED              leax  <CoWin,pcr point to CoWin name
01570   0915 8680                lda   #$80       get driver type code
01571   0917 8D13                bsr   L08D4      try and link it
01572
01573        *++
01574   0919 240D                bcc   ok
01575
01576        * Bug fix by Boisy on 08/22/2007 - The three lines below were inserted to check to see
01577        * the nature of the error that occurred fromfailing to link to CoWin/CoGrf.  Since CoWin/CoGr
01578        * also load GrfDrv, an error other than E$MNF might arise.  We expect an E$MNF if CoGrf is in
01579        * place instead of CoWin, but any other error just gets blown away without the three lines be
01580        * Now, if any error other than E$MNF is returned from trying to link to CoWin, we don't bothe



Microware OS-9 Assembler RS Version 01.00.00    04/28/2020 12:54:05                              Page 027
VTIO - Video Terminal I/O Driver for CoCo 3

01581        * to link to CoGrf... we just return the error as is.
01582   091B C1DD                cmpb  #E$MNF     compare the error to what we expect
01583   091D 1A01                orcc  #Carry     set the carry again (cmpb above clears it)
01584   091F 2607                bne   ok         if the error in B is not E$MNF, just leave this routine
01585
01586   0921 308CDC              leax  <CoGrf,pcr point to CoGrf name
01587   0924 8680                lda   #$80
01588   0926 8D04                bsr   L08D4
01589        *++
01590
/pre)
/box)

/section SAME FROM my lwasm vtio listing:

/box(
/pre(
0900 35E2             01557                  puls  pc,u,y,a   restore regs & return
                      01558
0902 436F5769EE       01559         CoWin    fcs   /CoWin/
0907 436F4772E6       01560         CoGrfName    fcs   /CoGrf/ ++
                      01561         *CC3GfxInt fcs   /CC3GfxInt/ ++
                      01562
                      01563         *
                      01564         * Try CoWin
                      01565         *
090C 3460             01566         FindWind pshs  u,y    preserve regs
090E 4F               01567                  clra       set window type
090F A7C81D           01568                  sta   <V.WinType,u
0912 308CED           01569                  leax  <CoWin,pcr point to CoWin name
0915 8680             01570                  lda   #$80   get driver type code
0917 8D13             01571                  bsr   L08D4    try and link it
                      01572
                      01573         *++
0919 240D             01574                  bcc   ok
                      01575
                      01576         * Bug fix by Boisy on 08/22/2007 - The three lines below were inserted to check to see
                      01577         * the nature of the error that occurred fromfailing to link to CoWin/CoGrf.  Since CoWin/CoGrf
                      01578         * also load GrfDrv, an error other than E$MNF might arise.  We expect an E$MNF if CoGrf is in
                      01579         * place instead of CoWin, but any other error just gets blown away without the three lines below.
                      01580         * Now, if any error other than E$MNF is returned from trying to link to CoWin, we don't bother trying
                      01581         * to link to CoGrf... we just return the error as is.
091B C1DD             01582                  cmpb  #E$MNF   compare the error to what we expect
091D 1A01             01583                  orcc  #Carry   set the carry again (cmpb above clears it)
091F 2607             01584                  bne   ok   if the error in B is not E$MNF, just leave this routine
                      01585
0921 308CE3           01586                  leax  <CoGrfName,pcr point to CoGrf name
0924 8680             01587                  lda   #$80
0926 8D04             01588                  bsr   L08D4
                      01589         *++
                      01590

/pre