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'[slightly OT] 8 and 16-bit memories'
1998\02\11@225959 by tsk3000

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I have a question.  Is it possible to connect two 8-bit memories (e.g.:
PROMs, Flash, SRAM) such that they will function as a 16-bit memory?
Can I just connect all the address and control lines together, and then
just use the data lines as if it were a 16-bit device?

TIA,
--
~Keith
spam_OUTtsk3000TakeThisOuTspamProdigy.Net
http://pages.prodigy.net/tsk3000/

1998\02\11@232046 by Sean Breheny

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At 09:56 PM 2/11/98 -0800, you wrote:
>I have a question.  Is it possible to connect two 8-bit memories (e.g.:
>PROMs, Flash, SRAM) such that they will function as a 16-bit memory?
>Can I just connect all the address and control lines together, and then
>just use the data lines as if it were a 16-bit device?
>
>TIA,
>--
>~Keith
>.....tsk3000KILLspamspam@spam@Prodigy.Net
>http://pages.prodigy.net/tsk3000/
>

Yes, you can. Just allow for the worst case access time, i.e. if you used
two slightly different chips, and one had a max 60ns time and another max
80ns, you have to allow the full 80ns. This of course goes for any of the
other specs, also.

Sean


+--------------------------------+
| Sean Breheny                   |
| Amateur Radio Callsign: KA3YXM |
| Electrical Engineering Student |
+--------------------------------+
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1998\02\12@033752 by Mike Keitz

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On Wed, 11 Feb 1998 21:56:24 -0800 Keith Burzinski <.....tsk3000KILLspamspam.....Prodigy.Net>
writes:
>I have a question.  Is it possible to connect two 8-bit memories
>(e.g.:
>PROMs, Flash, SRAM) such that they will function as a 16-bit memory?
>Can I just connect all the address and control lines together, and
>then
>just use the data lines as if it were a 16-bit device?

Yes, exactly.  The practice is common.  The devices should be the same
size and type.  If they are Flash ROMs, your erasing and programming
routines need to be written to account for the fact that there are
actually two seperate chips.  I think the newer Flash chips have "no
operation" commands so they can share the control lines even if only one
is to be written, or one completes faster than the other, etc.

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1998\02\12@145149 by tsk3000

picon face
Mike Keitz wrote:
>
> On Wed, 11 Feb 1998 21:56:24 -0800 Keith Burzinski <EraseMEtsk3000spam_OUTspamTakeThisOuTProdigy.Net>
> writes:
> >I have a question.  Is it possible to connect two 8-bit memories
> >(e.g.:
> >PROMs, Flash, SRAM) such that they will function as a 16-bit memory?
> >Can I just connect all the address and control lines together, and
> >then just use the data lines as if it were a 16-bit device?
>
> Yes, exactly.  The practice is common.  The devices should be the same
> size and type.  If they are Flash ROMs, your erasing and programming
> routines need to be written to account for the fact that there are
> actually two seperate chips.  I think the newer Flash chips have "no
> operation" commands so they can share the control lines even if only one
> is to be written, or one completes faster than the other, etc.
Okay cool!  :)

Now I have another question:  Any advise for programming two 8-bit
EPROMS with a program for, say, a 68000 CPU?  It's a 16-bit CPU with a
32-bit address bus; I'd like to use two 8-bit EPROMS for it's program
memory.  Is it possible for me to make, perhaps, an "even" and an "odd"
chip?  (I've got an EMP-10 programmer by Needhams...)

Cheers,
--
~Keith
tsk3000spamspam_OUTProdigy.Net
http://pages.prodigy.net/tsk3000/

1998\02\19@083808 by Theo Markettos

flavicon
face
Keith Burzinski wrote:
>
> Mike Keitz wrote:
> >
> > On Wed, 11 Feb 1998 21:56:24 -0800 Keith Burzinski <@spam@tsk3000KILLspamspamProdigy.Net>
> > writes:
> > >I have a question.  Is it possible to connect two 8-bit memories
> > >(e.g.:
> > >PROMs, Flash, SRAM) such that they will function as a 16-bit memory?
> > >Can I just connect all the address and control lines together, and
> > >then just use the data lines as if it were a 16-bit device?
> >
> > Yes, exactly.  The practice is common.
> Okay cool!  :)
>
> Now I have another question:  Any advise for programming two 8-bit
> EPROMS with a program for, say, a 68000 CPU?  It's a 16-bit CPU with a
> 32-bit address bus; I'd like to use two 8-bit EPROMS for it's program
> memory.  Is it possible for me to make, perhaps, an "even" and an "odd"
> chip?  (I've got an EMP-10 programmer by Needhams...)

That depends on what your assembler and programmer software handle.  The
simplest way is with a binary image - you just write a Basic program to
read the binary file, and write the first byte to file A, the second to
file B, the third to A and so on.  For a 68K, file A is the high EPROM
image and file B is the low image.  If your programmer software is
decent, it should be able to do this for you.

One note of caution with your previous question - if you parallel two 8
bit RAMs to make a 16 bit RAM on a 68K, beware that when you do a byte
write, only half of the data bus is valid, so you need to use /UDS and
/LDS to create separate write strobes for each RAM.  If you want an
example of this, I've documented it in my 68K Home Automation System
write-up at http://www.marketto.demon.co.uk/electronics/has/

Hope this helps,
Theo

--
Theo Markettos                  KILLspammarkettoKILLspamspamprl.research.philips.com
Interactive Systems Group
Philips Research Laboratories
Redhill, Surrey, UK

1998\02\19@184122 by Clyde Smith-Stubbs

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face
On Thu, Feb 19, 1998 at 01:37:03PM +0000, Theo Markettos wrote:
> That depends on what your assembler and programmer software handle.  The
> simplest way is with a binary image - you just write a Basic program to

Here is a C program that does just this. Before I get flamed for posting
code to the list, it's only 1K.

#include        <stdio.h>
#include        <string.h>
#include        <stdlib.h>

main(argc, argv)
char ** argv;
{
       FILE *  hi, * lo;
       int     c;
       char    filebuf[128];

       if(argc < 3) {
               fprintf(stderr, "Usage: binsplit input_file output_file_base\n")
;
               fprintf(stderr, "E.g. : binsplit foo.bin bar\n");
               fprintf(stderr, "       produces bar.hi and bar.lo\n");
               exit(1);
       }
       if(freopen(argv[1], "rb", stdin) == NULL) {
               perror(argv[1]);
               exit(1);
       }
       strcpy(filebuf, argv[2]);
       if(strchr(filebuf, '.')) {
               fprintf(stderr, "output file name should not include a file type
or
extension\n");
               exit(1);
       }
       strcat(filebuf, ".hi");
       if(!(hi = fopen(filebuf, "wb"))) {
               perror(filebuf);
               exit(1);
       }
       strcpy(filebuf, argv[2]);
       strcat(filebuf, ".lo");
       if(!(lo = fopen(filebuf, "wb"))) {
               perror(filebuf);
               exit(1);
       }
       while((c = getchar()) != EOF) {
               putc(c, hi);
               if((c = getchar()) == EOF) {
                       exit(0);
               }
               putc(c, lo);
       }
       exit(0);
}

--
Clyde Smith-Stubbs               |            HI-TECH Software
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