CUBIX/6809 updates

[Gooijen, Henk]

but it would make the entry of an address (16-bit) cumbersome.
You must enter it as an 8-bit high and an 8-bit low address.
I'd definately would go for 16 switches in this case, and also
16 LEDs for the address. Perhaps a matter of taste ...
 
What if you need access to xxx.nnn where xxx != 000 or 777?
Why pose limits that early in the design? You might regret such
a decision later ...
 
- Henk, PA8PDP

________________________________

Van: cctalk-bounces at classiccmp.org namens woodelf
Verzonden: ma 12-12-2005 23:05
Aan: On-Topic and Off-Topic Posts
Onderwerp: Re: CUBIX/6809 updates



Gooijen, Henk wrote:

>Using the pdp8/e design fron panel for the 6809 is possible, but ...
>there are only 15 Address LEDs (12 plus 3 for EMA), and the other row is
>12 LEDs, so the upper 4 would not be used. The rotary knob could be used
>to display A or B (or DP or CC) but to display X, Y, U, SP, PC you need
>16 LEDs. There are just 12 switches, and you could use the SW switch as
>the 13th, but still, to enter a 16-bit address would be cumbersome.
>So, the pdp8/e panel is not the best choice, but the implementation
>-hardware wise- is always possible. Software is what makes it 'tick' :-)
>and I am sure that's "piece of cake" for you, Dave.
> 
>
As you all know by now  I am building a 9/18 bit cpu. My front panel
will be limited to
9 data switches and a address page switch. This lets me access 000.nnn
and 777.nnn
memory on address load. Since I plan only to use  the swr for short
programs on page zero
and have a bootstrap rom  and I/O on the last page this more than ample
for me.
A similar restricted front panel may be possible as well for the 6809 as
data is byte orientated.
Ben alias woodelf






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