[A83] Re: LD A,R ; LD R,A

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[A83] Re: LD A,R ; LD R,A


If you can open your 86 and give me a list of all the chip numbers, I can
find out the RAM type.


Michael Vincent
Detached Solutions - www.detacheds.com
Radical Software - www.radicalsoft.org

----- Original Message -----
From: "Kirk Meyer" <kirk.meyer@colorado.edu>
To: <assembly-83@lists.ticalc.org>
Sent: Saturday, July 14, 2001 2:27 PM
Subject: [A83] Re: LD A,R ; LD R,A


>
> Hmm... someone did a test on TI-86 with that loop, and their memory faded
> (crashing at a certain point, as those very instructions also faded). Of
> course, it's quite possible that 86 and 83 differ in design.
>
> Yeah the only real use of R is as a random number, but only twice per user
> key press (once while you wait for it, once while you wait for them to
> release it) -- use it much more than that and you simply see a recurring
> mathematical pattern, because usually in loops the number of instructions
is
> constant.
>
> An interesting idea would be to write some obfuscated Z80 code which
loaded
> 0 into the R register, executed some instructions, and then loaded the
value
> from R when it got to the value it needed. You'd have to disable
interrupts
> of course =)
>
> -----Original Message-----
> From: assembly-83-bounce@lists.ticalc.org
> [mailto:assembly-83-bounce@lists.ticalc.org]On Behalf Of Michael Vincent
> Sent: Saturday, July 14, 2001 10:30 AM
> To: assembly-83@lists.ticalc.org
> Subject: [A83] Re: LD A,R ; LD R,A
>
>
>
> The 83/83+/83+ SE all use a static RAM chip though. From the docs, "The
> asynchronous and
> static nature of the memory requires no external clock or refresh
circuit."
> I would think then that the R register wouldn't be needed?
>
>
> Michael Vincent
> Detached Solutions - www.detacheds.com
> Radical Software - www.radicalsoft.org
>
> ----- Original Message -----
> From: <ComAsYuAre@aol.com>
> To: <assembly-83@lists.ticalc.org>
> Sent: Saturday, July 14, 2001 7:14 AM
> Subject: [A83] Re: LD A,R ; LD R,A
>
>
> > From "Programming the Z80" by Rodnay Zaks:
> >
> > "The R register is the memory-refresh register.  It is provided to
refresh
> > dynamic memories automatically.  Such a register has traditionally been
> > located outside the microprocessor, since it is associated with the
> dynamic
> > memory.  It is a convenient feature which minimizes the amount of
external
> > hardware for some types of dynamic memories."
> >
> > Basically, the r register gets incremented each byte of instruction
code.
> > It's used in some pseudo-random number generators, such as ztetris, but
it
> > can't be used without some sort of variable-length delay between uses
> (such
> > as waiting for someone to hit a key), because otherwise the output won't
> be
> > very random.  Otherwise, it has little practical use on calculators.
> >
> >
> > In a message dated 7/14/2001 2:44:27 AM Eastern Daylight Time,
> > hyper@hysoft-automation.com writes:
> >
> >
> > >
> > > When using the tasm80.tab file, I
> > > came upon the opcodes LD A,R and LD R,A
> > > They have a '1' at the end of the line
> > > (the class), so I guess they're four our
> > > processor. But I'm curious as to that this
> > > R means. It can't be meaning 'other registers'
> > > since they're all taken care for elsewhere in the
> > > table file. My guess is that it's a special system
> > >
> >
> >
> >
> >
> > ----
> > Jonah Cohen
> > <ComAsYuAre@aol.com>
> > http://jonah.ticalc.org
> >
> >
> >
> >
>
>
>
>
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