using a 6522 with a 6802

09 Feb 2008 16:18:37

Lee K. Gleason

I'm trying to put together a small controller, using a Motorola 6802 (more
or less, a 6800 with some onboard RAM), a 27C512 EPROM, and a 6522 VIA (you
know, old school, circa 1980 style). It's designed in the simplest way
possible, simple chip select, oscillator chip clock, really nothing
complicated about it. I'm having trouble getting it to work though. All the
signals look right, but the 6522 never does anything. I'm wondering if just
connecting the E clock output from the 6802 to the 6522 CLK is causing any
problems, or if more elaborate handling of the timing is necessary. Anyone
out there ever use a 6522 in a 6800 environment successfully? Any tricks to
it?
--
Lee K. Gleason N5ZMR
Control-G Consultants
lee.gleason@comcast.net

11 Feb 2008 00:21:43

Tom2000

Re: using a 6522 with a 6802

On Sat, 9 Feb 2008 16:18:37 -0600, "Lee K. Gleason"
<lee.gleason@comcast.net > wrote:

> I'm trying to put together a small controller, using a Motorola 6802 (more
>or less, a 6800 with some onboard RAM), a 27C512 EPROM, and a 6522 VIA (you
>know, old school, circa 1980 style). It's designed in the simplest way
>possible, simple chip select, oscillator chip clock, really nothing
>complicated about it. I'm having trouble getting it to work though. All the
>signals look right, but the 6522 never does anything. I'm wondering if just
>connecting the E clock output from the 6802 to the 6522 CLK is causing any
>problems, or if more elaborate handling of the timing is necessary. Anyone
>out there ever use a 6522 in a 6800 environment successfully? Any tricks to
>it?

Wow, a blast from the past.

I've done it, but that was over 20 years ago, and certainly don't
remember exactly how. Hanigng a 6522 on the Motorola bus isn't
difficult, though. I'd suggest that you carefully read the data
sheets for both chips, paying particular attention to the clock phase,
R/W, and chip select conditions. You'll find your solution there.

If you still have trouble, switch to a 6502 processor. If you can
find one. :-)

Good luck!

Tom

11 Feb 2008 03:02:58

Jakthehammer

Re: using a 6522 with a 6802

"Tom2000" <abuse@giganews.net > wrote in message
news:0610r3pb6b5puc934eved52ealq67g74kc@4ax.com...
> On Sat, 9 Feb 2008 16:18:37 -0600, "Lee K. Gleason"
> <lee.gleason@comcast.net> wrote:
>
>> I'm trying to put together a small controller, using a Motorola 6802
>> (more
>>or less, a 6800 with some onboard RAM), a 27C512 EPROM, and a 6522 VIA
>>(you
>>know, old school, circa 1980 style). It's designed in the simplest way
>>possible, simple chip select, oscillator chip clock, really nothing
>>complicated about it. I'm having trouble getting it to work though. All
>>the
>>signals look right, but the 6522 never does anything. I'm wondering if
>>just
>>connecting the E clock output from the 6802 to the 6522 CLK is causing
>>any
>>problems, or if more elaborate handling of the timing is necessary.
>>Anyone
>>out there ever use a 6522 in a 6800 environment successfully? Any tricks
>>to
>>it?
>
> Wow, a blast from the past.
>
> I've done it, but that was over 20 years ago, and certainly don't
> remember exactly how. Hanigng a 6522 on the Motorola bus isn't
> difficult, though. I'd suggest that you carefully read the data
> sheets for both chips, paying particular attention to the clock phase,
> R/W, and chip select conditions. You'll find your solution there.
>
> If you still have trouble, switch to a 6502 processor. If you can
> find one. :-)
>
> Good luck!
>
> Tom

Time to use ICE....Heehee.......

11 Feb 2008 09:25:37

Steve

Re: using a 6522 with a 6802

"Lee K. Gleason" <lee.gleason@comcast.net > wrote in message
news:O-OdnQp7KssjuzPanZ2dnUVZ_ualnZ2d@comcast.com...
> I'm trying to put together a small controller, using a Motorola 6802
> (more
> or less, a 6800 with some onboard RAM), a 27C512 EPROM, and a 6522 VIA
> (you
> know, old school, circa 1980 style). It's designed in the simplest way
> possible, simple chip select, oscillator chip clock, really nothing
> complicated about it. I'm having trouble getting it to work though. All
> the
> signals look right, but the 6522 never does anything. I'm wondering if
> just
> connecting the E clock output from the 6802 to the 6522 CLK is causing any
> problems, or if more elaborate handling of the timing is necessary. Anyone
> out there ever use a 6522 in a 6800 environment successfully? Any tricks
> to
> it?
> --
> Lee K. Gleason N5ZMR
> Control-G Consultants
> lee.gleason@comcast.net
>
>

I've used that combination successfully. The 6522 was a much better UART
than the Motorola part was. But unfortunately, it was so long ago that I
can't remember how the clocking was done. I doubt it was much external
logic - we didn't use much more than PAL's in those days. Check to see if
its clock needs to be inverted relative to the 6802 to align the Rd/Wr or CS
edges where they need to be. I think clock phase was one of the differences
between the 6502 and 6802 processors.

I'm curious as to why you would not just use one of the thousands of
available Flash based microcontrollers for your project. They cost less,
there are less obsolescence issues, and all the hardware is already debugged
for you. Most have serial emulation available for under $100. I loved the
6809 in its day, but its just been overshadowed in speed, size and cost. If
your software is expected to have any complexity at all, don't underestimate
the difficulties of debugging without emulation. It takes 10 times longer
than it will with even the simplest emulation tools.

Good luck with your project,
Steve

11 Feb 2008 11:06:30

Jim

Re: using a 6522 with a 6802

In article <O-OdnQp7KssjuzPanZ2dnUVZ_ualnZ2d@comcast.com >, Lee K.
Gleason <lee.gleason@comcast.net > wrote:

> I'm trying to put together a small controller, using a Motorola 6802 (more
> or less, a 6800 with some onboard RAM), a 27C512 EPROM, and a 6522 VIA (you
> know, old school, circa 1980 style). It's designed in the simplest way
> possible, simple chip select, oscillator chip clock, really nothing
> complicated about it. I'm having trouble getting it to work though. All the
> signals look right, but the 6522 never does anything. I'm wondering if just
> connecting the E clock output from the 6802 to the 6522 CLK is causing any
> problems, or if more elaborate handling of the timing is necessary. Anyone
> out there ever use a 6522 in a 6800 environment successfully? Any tricks to
> it?

I just looked at some old notes that I had - using a 68HC11 and a 6522.
It looks like I ran the E line directly into ph2 (pin 25) - no special
buffering at all. I put A12 into CS1 and then used a 74hc139 to decode
A13-A14-A15 into CS2. Note that CS2 is inverted so is active low. IRQ,
and R/W run straight in. If you're careful with your connections, it
should work (I know that board is still around here somewhere - it
worked well for many years for me).

Jim

12 Feb 2008 02:33:36

Rich Grise

Re: using a 6522 with a 6802

On Mon, 11 Feb 2008 00:21:43 -0800, Tom2000 wrote:

> If you still have trouble, switch to a 6502 processor. If you can
> find one. :-)

What the hell, build one!
http://freenet-homepage.de/dieter.02/m02.htm
Found on:
http://freenet-homepage.de/dieter.02/
Found on:
http://www.6502.org/homebuilt

Cheers!
Rich

11 Feb 2008 23:00:36

Lee K. Gleason

Re: using a 6522 with a 6802

"Steve" <sjburke1@comcast.net > wrote in message
news:e66dnUfs4NPuxy3anZ2dnUVZ_uevnZ2d@comcast.com...
>
> "Lee K. Gleason" <lee.gleason@comcast.net> wrote in message
> news:O-OdnQp7KssjuzPanZ2dnUVZ_ualnZ2d@comcast.com...
> > I'm trying to put together a small controller, using a Motorola 6802
> > (more
> > or less, a 6800 with some onboard RAM), a 27C512 EPROM, and a 6522 VIA
> > (you
> > know, old school, circa 1980 style).

> I'm curious as to why you would not just use one of the thousands of
> available Flash based microcontrollers for your project. They cost less,
> there are less obsolescence issues, and all the hardware is already
debugged
> for you. Most have serial emulation available for under $100. I loved the
> 6809 in its day, but its just been overshadowed in speed, size and cost.
If
> your software is expected to have any complexity at all, don't
underestimate
> the difficulties of debugging without emulation. It takes 10 times longer
> than it will with even the simplest emulation tools.
>
>

Thanks all for the info. I'm doing this out of nostalgia - when 6800s were
new, I was too busy and too hardware-ignorant to experiment with them. Now,
I've got some spare time, and a lot more expereince under my belt, so I'm
revisiting the chips I missed out on back then..
--
Lee K. Gleason N5ZMR
Control-G Consultants
lee.gleason@comcast.net

11 Feb 2008 23:28:21

Tim Williams

Re: using a 6522 with a 6802

"Tom2000" <abuse@giganews.net > wrote in message
news:0610r3pb6b5puc934eved52ealq67g74kc@4ax.com...
> If you still have trouble, switch to a 6502 processor. If you can
> find one. :-)

Obviously, just go to the future and purchase a Terminator unit.
http://en.wikipedia.org/wiki/6502#6502_in_popular_culture

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms

11 Feb 2008 23:53:46

Tom2000

Re: using a 6522 with a 6802

On Mon, 11 Feb 2008 23:00:36 -0600, "Lee K. Gleason"
<lee.gleason@comcast.net > wrote:

>
> Thanks all for the info. I'm doing this out of nostalgia - when 6800s were
>new, I was too busy and too hardware-ignorant to experiment with them. Now,
>I've got some spare time, and a lot more expereince under my belt, so I'm
>revisiting the chips I missed out on back then..

Well, Lee, if it's about nostalgia, then all is forgiven. :-) I can
certainly understand your motivation, and it's a good one. (I just
received an HP-11C calculator that I purchased on eBay for nothing
more than nostalgia.)

FWIW, I used a 6802 for the first computer that I "designed" and built
from scratch.

I wire wrapped it, and wrote my own monitor by hand-assembling the
code, then punching it into a borrowed EPROM programmer by hand. It
took quite a few tries since debugging involved punching another
EPROM.

I had a lot of fun with that project, and really learned a bunch.

Enjoy your project. I know you're having fun.

Very 73,

Tom AB9B

11 Feb 2008 23:32:33

Tom2000

Re: using a 6522 with a 6802

On Tue, 12 Feb 2008 02:33:36 GMT, Rich Grise <rich@example.net > wrote:

>On Mon, 11 Feb 2008 00:21:43 -0800, Tom2000 wrote:
>
>> If you still have trouble, switch to a 6502 processor. If you can
>> find one. :-)
>
>What the hell, build one!
>http://freenet-homepage.de/dieter.02/m02.htm
>Found on:
>http://freenet-homepage.de/dieter.02/
>Found on:
>http://www.6502.org/homebuilt
>
>Cheers!
>Rich

Good grief! I can understand an attachment to a particular processor
or family, (Like a previous poster, I was also pretty fond of the
6809), but this is going to extremes.

Thanks, Rich!

Tom

11 Feb 2008 23:35:29

Tom2000

Re: using a 6522 with a 6802

On Mon, 11 Feb 2008 23:28:21 -0600, "Tim Williams"
<tmoranwms@gmail.com > wrote:

>"Tom2000" <abuse@giganews.net> wrote in message
>news:0610r3pb6b5puc934eved52ealq67g74kc@4ax.com...
>> If you still have trouble, switch to a 6502 processor. If you can
>> find one. :-)
>
>Obviously, just go to the future and purchase a Terminator unit.
>http://en.wikipedia.org/wiki/6502#6502_in_popular_culture
>
>Tim

Wow. Is there *anything* that isn't in the Wikipedia?

This was my introduction to the 6502:

11 Feb 2008 23:36:32

Tom2000

Re: using a 6522 with a 6802

12 Feb 2008 15:44:43

Steve

Re: using a 6522 with a 6802

"Lee K. Gleason" <lee.gleason@comcast.net > wrote in message
news:IvqdnTDIxeVruizanZ2dnUVZ_g6dnZ2d@comcast.com...
>
> "Steve" <sjburke1@comcast.net> wrote in message
> news:e66dnUfs4NPuxy3anZ2dnUVZ_uevnZ2d@comcast.com...
>>
>> "Lee K. Gleason" <lee.gleason@comcast.net> wrote in message
>> news:O-OdnQp7KssjuzPanZ2dnUVZ_ualnZ2d@comcast.com...
>> > I'm trying to put together a small controller, using a Motorola 6802
>> > (more
>> > or less, a 6800 with some onboard RAM), a 27C512 EPROM, and a 6522 VIA
>> > (you
>> > know, old school, circa 1980 style).
>
> > I'm curious as to why you would not just use one of the thousands of
>> available Flash based microcontrollers for your project. They cost less,
>> there are less obsolescence issues, and all the hardware is already
> debugged
>> for you. Most have serial emulation available for under $100. I loved the
>> 6809 in its day, but its just been overshadowed in speed, size and cost.
> If
>> your software is expected to have any complexity at all, don't
> underestimate
>> the difficulties of debugging without emulation. It takes 10 times longer
>> than it will with even the simplest emulation tools.
>>
>>
>
> Thanks all for the info. I'm doing this out of nostalgia - when 6800s
> were
> new, I was too busy and too hardware-ignorant to experiment with them.
> Now,
> I've got some spare time, and a lot more expereince under my belt, so I'm
> revisiting the chips I missed out on back then..
> --
> Lee K. Gleason N5ZMR
> Control-G Consultants
> lee.gleason@comcast.net
>
>

Nothing wrong with having fun....

Compared with Intel micros, the Motorola parts were wonderful for assembly
language: regular architectures, CC flags that were consistent regardless of
the op code, and few special purpose registers. When the 6809 came out, it
fixed the biggest 6802 flaw IMO - a single index register with limited
addressing modes.

I'm surprised you can still buy the parts.

Good luck
Steve

12 Feb 2008 16:44:59

Phil Hobbs

Re: using a 6522 with a 6802

Tom2000 wrote:
> On Mon, 11 Feb 2008 23:28:21 -0600, "Tim Williams"
> <tmoranwms@gmail.com> wrote:
>
>> "Tom2000" <abuse@giganews.net> wrote in message
>> news:0610r3pb6b5puc934eved52ealq67g74kc@4ax.com...
>>> If you still have trouble, switch to a 6502 processor. If you can
>>> find one. :-)
>> Obviously, just go to the future and purchase a Terminator unit.
>> http://en.wikipedia.org/wiki/6502#6502_in_popular_culture
>>
>> Tim
>
> Wow. Is there *anything* that isn't in the Wikipedia?

Sure--such as any balanced and detailed discussion of controversial issues.

Cheers

Phil Hobbs