Z80 home brew with FDC

[Roy J. Tellason]

On Monday 22 September 2008 15:24, Ethan Dicks wrote:
> On Mon, Sep 22, 2008 at 12:56:56PM -0400, Roy J. Tellason wrote:
> > On Monday 22 September 2008 10:12, dwight elvey wrote:
> > > Hi
> > >  Its a shame that the more easily available 555 chips don't
> > > work well into the Megaherts. They are easy to get and a
> > > pair of them would have made a reasonable separator.
> > >  I have a schematic for the separator used on my Polymorphic
> > > computer. It uses another hard to get VCO chip. It uses
> > > a MC4024, an external charge pump, 96L02 oneshot and
> > > a few more TTLs.
> > > Dwight
> >
> > I may actually have some of those,  they were used in certain versions of
> > the c64 along with the 74LS629...
>
> Where was there a 96L02 in the C-64?

There wasn't,  though the early versions of the board used a MC4024 and a 
74LS629 along with a couple more common LSTTL parts.

> As it happens, I do have quite a few 96L02s lying around.  I was just
> wondering what they were good for.  Now I know.

I think I have one,  and one 9602,  both probably salvaged from scrap terminal 
boards.  I remember talking to a guy on the phone while the company I was 
with at the time was evaluating a dual cassette deck,  intended to be hooked 
up to the H11 system I'd built for them.  I was trying to prototype some sort 
of an interface card (never did get that working),  and the guy on the other 
end of the phone was very much against the 74123 and LS123,  though my 
recollection of the exact problem with them is a little fuzzy.  Temperature 
instability,  perhaps,  or something of the sort.  I only mention this 
because it would seem to explain the use of the 9602 or 96LS02 when the whole 
rest of the board was more standard TTL...

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
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