Subject: Re: DF32 emulator

From: Charles <[email-masked]>
Date: Mon Apr 7 21:05:01 2003

On Mon, 07 Apr 2003 12:42:27 -0500, you wrote:

>... shows the use of DMCA and DCEA to clear a disk, rather than DEAL.
>
>
>Not exactly what you were looking for, but perhaps someone else has the

Crap. Oh well, I was planning a Revision B anyway, to take care of
the bugs I already discovered (such as DFSE skipping on error like
an RF08 instead of skip-on-no-error).

I guess I'll have to figure out how to clear the LS191 counters I
used for registers. Maybe there's a 4 bit counter with a clear
input I can use. The simplest way would be to force 0's into the
load inputs to the counters for EMA and EA and strobe the clock
line with that IOT, but that would require a couple of chips and
there is just no more room (and keep the board "cheap", standard
160x100mm Eurocard size and two-layer). I could put a lot more
logic on a 4-layer board but they cost a LOT more. All those
12-bit busses take up a lot of PCB real estate!

Meanwhile I think it'll work with a non-expanded (4K) machine like
my 8/L ;) Back to the drawing board!

-Charles

---

From: Ethan Dicks <[email-masked]>
Date: Mon Apr 7 23:23:00 2003

> >... shows the use of DMCA and DCEA to clear a disk, rather than DEAL.
.
.
.
> used for registers... The simplest way would... require a couple 
> of chips and there is just no more room (and keep the board "cheap",
> standard 160x100mm Eurocard size and two-layer).

SMT?  I've done a bit of SO soldering and it's not that hard.  A
decent temp-controlled iron and some masking tape or blu-tack to
hold the parts in place so you can tack down the corners.

However you solve it, don't give up.  This is a cool idea that
just needs a little tweaking.

-ethan