[Coco] Re: 64K Mode
John Collyer
johncollyer at zoominternet.net
Wed Jan 14 13:08:24 EST 2004
It's documented.
See Tepco's (ASSEMBLY LANGUAGE PROGRAMMING For The TRS-80 COLOR COMPUTER)
book.
John Collyer
----- Original Message -----
From: <jdaggett at gate.net>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Wednesday, January 14, 2004 1:06 PM
Subject: Re: [Coco] Re: 64K Mode
> John
>
> Then that is a undocumented. Accoording to the Service Manual the
> R0 and P registers are not documented. Leaving one to believe that
> those SAM features are not supported.
>
> james
>
>
> On 14 Jan 2004 at 12:52, John Collyer wrote:
>
> From: "John Collyer"
> <johncollyer at zoominternet.net>
> To: "CoCoList for Color Computer Enthusiasts"
> <coco at maltedmedia.com>
> Subject: Re: [Coco] Re: 64K Mode
> Date sent: Wed, 14 Jan 2004 12:52:57 -0500
> Send reply to: CoCoList for Color Computer Enthusiasts
> <coco at maltedmedia.com>
> <mailto:coco-
> request at maltedmedia.com?subject=unsubscribe>
> <mailto:coco-
> request at maltedmedia.com?subject=subscribe>
>
> > That's true, but it also works on a coco3. Try it.
> > Run SuperPatch EDTASM+ on a coco3 emulator
> > and see if it don't work. I'll bet it does.
> >
> > John Collyer
> >
> > ----- Original Message -----
> > From: <jdaggett at gate.net>
> > To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> > Sent: Wednesday, January 14, 2004 12:57 PM Subject: Re: [Coco] Re: 64K
> > Mode
> >
> >
> > > John
> > >
> > > That is what I have been saying. This is for the SAM CHIP ONLY
> > > COCO 1 and 2 Only
> > >
> > > In Memeory Map type 0 (ZERO)
> > >
> > > Ram is in the lower 32K and ROM and vectors in the upper 32K.
> > > With 64K of ram on board, the Ram is configured as two (2) banks of
> > > 32K mapped in the lower 32K of the memory map. The "P" register
> > > controls which page is mapped in.
> > >
> > > In Memeory Map Type 1 (ONE)
> > >
> > > Ram is configured from address $0000 to $FEFF. The upper 256
> > > bytes are not accessable as they are I/O and vector sapce.
> > >
> > > james
> > >
> > >
> > >
> > > On 14 Jan 2004 at 10:49, John Collyer wrote:
> > >
> > > From: "John Collyer"
> > > <johncollyer at zoominternet.net>
> > > To: "CoCoList for Color Computer Enthusiasts"
> > > <coco at maltedmedia.com>
> > > Subject: Re: [Coco] Re: 64K Mode
> > > Date sent: Wed, 14 Jan 2004 10:49:25 -0500
> > > Send reply to: CoCoList for Color Computer Enthusiasts
> > > <coco at maltedmedia.com>
> > > <mailto:coco-
> > > request at maltedmedia.com?subject=unsubscribe>
> > > <mailto:coco-
> > > request at maltedmedia.com?subject=subscribe>
> > >
> > > > OK, Everyone lets get this correct. Here are the details:
> > > >
> > > > The page number bit, P1 is cleared by BASIC when the computer is
> > > > turned on. The effect of P1 set can only be used by a 64K CoCo. A
> > > > 64K RAM is considered as two 32K pages. When the page number bit
> > > > is clear page 0 is the first 32K and page 1 is the upper 32K.
> > > > With TY clear (ROM/RAM mode) and the page number bit clear the
> > > > first 32K RAM occupies addresses $0000 through $7FFF and ROM
> > > > extends upward from there. Setting the page number bit results in
> > > > the upper 32K of RAM, which was not accessible with TY clear,
> > > > being accessed by addresses $0000 through $7FFF. This allows you
> > > > to have two BASIC programs in RAM at the same time. One in Page 0
> > > > and the other in page 1.
> > > >
> > > > TY | Memory map mode | Set | Clear
> > > > $FFDF | $FFDE
> > > >
> > > > P1 | Page Number | Set | Clear
> > > > $FFD5 $FFD4
> > > >
> > > > This is how it really works!
> > > >
> > > > John Collyer
> > > >
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: <jdaggett at gate.net>
> > > > To: "CoCoList for Color Computer Enthusiasts"
> > > > <coco at maltedmedia.com> Sent: Tuesday, January 13, 2004 11:35 PM
> > > > Subject: Re: [Coco] Re: 64K Mode
> > > >
> > > >
> > > > >
> > > > > What ever.
> > > > >
> > > > > Correct I shorted the upper range 16 bytes. $FFF0 is the start
> > > > > of I/O. The Ram is switched in two banks and are located between
> > > > > $0000 and $7FFF when memory map type 0 is selected.
> > > > >
> > > > > The HD63x09 has vector for illegal opcode trap at $FFF0 and
> > > > > $FFF1. The MC68x09 does not.
> > > > >
> > > > > james
> > > > >
> > > > > On 13 Jan 2004 at 18:04, Alex wrote:
> > > > >
> > > > > From: Theodore (Alex) Evans
> > > > > <alxevans at concentric.net>
> > > > > Subject: Re: [Coco] Re: 64K Mode
> > > > > Date sent: Tue, 13 Jan 2004 18:04:41 -1000
> > > > > To: CoCoList for Color Computer Enthusiasts
> > > > > <coco at maltedmedia.com>
> > > > > Send reply to: CoCoList for Color Computer Enthusiasts
> > > > > <coco at maltedmedia.com>
> > > > > <mailto:coco-
> > > > > request at maltedmedia.com?subject=unsubscribe>
> > > > > <mailto:coco-
> > > > > request at maltedmedia.com?subject=subscribe>
> > > > >
> > > > > > On Jan 13, 2004, at 3:39 PM, jdaggett at gate.net wrote:
> > > > > >
> > > > > > > The Sam Chip in the Sam Chip of the CoCo 1/2 hasa two
> > > > > > > memeory map types
> > > > > > >
> > > > > > > Type 0 is ram from $0000 to $7FFF and Rom from $8000 to
> > > > > > > $FDFF and from $FFF2 to $FFFF. $FF00 to $FFDF is I/O and
> > > > > > > $FFE0 to $FFF1 unused.
> > > > > > >
> > > > > > > Type 1 is all ram $0000 to $FDFF. $FF00 to $FFDF is I/O and
> > > > > > > $FFE0 to $FFF1 unused. $FFF2 to $FFFF is ROM and vector
> > > > > > > location.
> > > > > >
> > > > > > I am almost positive that the the area switched extends up to
> > > > > > $FEFF with only 256 bytes for I/O and vectors. In fact
> > > > > > according to some notes that I made a long time ago the
> > > > > > destinations for the all but one of the 6809 vectors (I don't
> > > > > > have a note for the 6309 unimplemented instruction at $FFF0)
> > > > > > lie in in the FE00-$FEFF range. SWI3 pointing to $FEEE, SWI2
> > > > > > to $FEF1, FIRQ to $FEF4, IRQ to $FEF7, SWI1 to $FEFA, and NMI
> > > > > > to $FEFD with reset being the exception which points to $8C1B
> > > > > >
> > > > > >
> > > > > > --
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