[A83] Re: LD A,R ; LD R,A
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[A83] Re: LD A,R ; LD R,A
Isn't static memory better, then?
What are the differences (pro's/ against's)
of dynamic and static memory
>
> Dyamic memories must be updated or they lose their information. I believe
> standard PC memory is dynamic, requiring refresh cycles.
>
>
> Michael Vincent
> Detached Solutions - www.detacheds.com
> Radical Software - www.radicalsoft.org
>
> ----- Original Message -----
> From: "Henk Poley" <HPoley@DDS.nl>
> To: <assembly-83@lists.ticalc.org>
> Sent: Saturday, July 14, 2001 10:53 AM
> Subject: [A83] Re: LD A,R ; LD R,A
>
>
> >
> > > Van: Peter-Martijn Kuipers <hyper@hysoft-automation.com>
> > >
> > > Does this mean that the R register can be freely used, or are there
> > > other less obvious uses for?
> >
> > From AsmGuru (found the same info also on other places):
> >
> > <<Q-1: I AND R REGISTERS. What they do.
> >
> > I is the Interrupt page address register [..]
> >
> > R is the memory Refresh register. The Z-80 CPU contains a memory refresh
> > counter to enable dynamic memories to be used with the same ease as static
> > memories. Seven bits of this 8 bit register are automatically incremented
> > after each instruction fetch. The eight bits will remain as programmed
> with
> > the LD R,A instruction.>>
> >
> > So you can use the R register to 'store' something, but only if that's one
> > bit...
> >
> > <<The data in the refresh counter is sent out on the lower portion of the
> > address bus along with a refresh control signal while the CPU is decoding
> > and executing the instruction. The programmer can load the R register for
> > testing purposes, but this register is normally NOT used by the
> programmer.
> > During refresh, the contents of the I register are placed on the upper 8
> > bits of the address bus.>>
> >
> > The last thing told here doesn't apply to the Ti's, they only have stactic
> > RAM.
> >
> > I don't really understand in what way the R register is usefull for
> dynamic
> > memories (nor what dynamic memories exactly are).
> >
> > Henk Poley
> >
> >
> >
> >
>
>
>
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