Date   : Mon, 24 Mar 2008 16:15:11 +0100 (GMT)
From   : johan@... (Johan Heuseveldt)
Subject: TUBE chip, accessing 'Parasite' side

Hi Jonathan,

On Sat 22 Mar, Jonathan Graham Harston wrote:
> Johan Heuseveldt wrote:

[snip]

> > The current design is not FLEX compatible anyway, as there is no
> > appropiate MMU present; intentionaly though. Not sure I like
>  
> You don't need an MMU to be FLEX compatible, it can be a single
> 64K single-bank FLEX system.

No doubt.
But most of what I saw uses more than that. Even then.
I don't know how much use is such a system with only 64K.

The old Acorn version has far less than 64 K, and that was FLEX compatible
too! I suppose that FLEX applications have changed since, and the minimum
is (regarded as?) 64K.

Also, there's hardly any fun in that.
Using two 74HC219 and a single 1MByte static RAM with (most of) the glue
logic in 1 or 2 GALs, is far more attractive to me!

There is a timing issue for the 219 I'm not certain of, and I need to
knoe more of managing software in FLEX, if there's a manager in the first
place. But that's for later.

For now I concentrate on the 6809 type A(corn alike) in its test-incarnation
with 128K Static RAM, VERO board mounted, and manually wired.


Johan

-- 
Johan Heuseveldt <johan@...              >
  aka  waarland

  The best place is a Riscy place
 
How do you explain school to a higher intelligence?
Elliot, "E.T."