BASREG.THD  --- Copyright 1987 by Phil Wheeler

An original compilation of Compuserve Model 100 Forum messages for use by
Forum members only.

Employing M/L subroutines in Basic programs is straight-forward -- as long
as you need only pass parameters to the A and HL registers.  Sometimes more
is needed, however.  This is a technical discussion of some alternate ways
to do this -- short of writing a machine language program!!

Message range: 157880 to 157993
Dates: 10/8/87 to 10/9/87


Sb: #registers
Fm: ron gumina 76246,600
To: sysop

I am developing a BASIC program fo the Model 102.  There are several standard
ROM routines I'd like to use that return data in the CPU registers (A,HL,FLAG,
etc.).  Is there a way to access these registers directly from BASIC ??

Thanks for any help you might be able to offer !!!


Fm: Tony Anderson 76703,4062
To: ron gumina 76246,600

Not generally.  The registers are part of the CPU, and there aren't any peeks
that can access them.  You might try taking a look at the Model 100 ROM map,
which will generally apply to the 102 as well.  It's in 8 files in DL8,
starting with 100ROM.RC0 through 100ROM.RC6 and finishing with 100RAM.RDC.


Fm: Stan Wong 70346,1267
To: ron gumina 76246,600

Ron, I've had the same desire to access the registers from Basic.  Can't be
done easily but it can be done (I think).  The general procedure goes
 something like this:

     1.  Create three arrays, two for
         code, the other for data,
     2.  Poke M/L code into first array
         which will get registers you
         want and push them onto the
         stack,
     3.  CALL the m/l code in the first
         array without any A or H
         parameters,
     4.  The code in the second array
         will move the data on the
         stack to the third array,
     5.  Call the second array m/l code
         with the address of the third
         array in HL.

Sounds complex (and it is) but I think it should work. Fortunetly once set
up it should be easy to use.  I hope someone has a simpler solution
(assuming this works).


Fm: Tony Anderson 76703,4062
To: Stan Wong 70346,1267

Stan, since this question has come up more than once, I'd like to see any code
you've developed that will do it.  There is a ROM routine that will convert the
binary into ASCII figures, and presumably, you could then move that into the
accumulator and print it.  Have you looked at that approach, or done anything
other than running it around the old brain cells?


Fm: Denny Thomas 76701,40
To: Stan Wong 70346,1267

 Your system will work, but as you say, it's quite complex. There is another
method that is used in QIKCHK (DL7) that is slightly easier. You set aside an
integer variable that will be the the transfer vehicle. Store the value you
wish to pass to ML there and then do a VARPTR call to your routine. That part
isn't really very impressive, but if you save the HL address of the variable
for later use, you can then pass values *back* to basic via that variable. It
works pretty efficiently if you stick to integer variables; single and double
precision variables are another mattter altogether.