Anyone have a line on batteries for the NLS

[Tony Duell]

> 
> Tony Duell wrote:
> > Worse than that, as you mention in passing, in some designs the battery 
> > acts as a shunt regulator and stabilises the votlage on one of the main 
> > supply lines.
> 
> The Microwriter does this, with four NiCad cells acting as a
> "5V regulator".  Naturally, my Microwriter came with four dud cells,
> but I only paid a pound for it at a Bristol car boot sale!

I am pretty sure my Microwriter, an MW4 model, has a zener diode across 
the battery pack to protect the machine if the battery goes open. 

Incidnetally, one thing to watch for on this machine is that the power 
'swtich (actually a pair of VMOS FETs in parallel) is in the -ve rail. 
There's a common positive to all the ICs and seaprate awitched and 
unswitched grounds.

Alas my MW4 seems to have a ROM problem (in that some chords are 
misrecognised, it is not a switch/wirign/diode fault). If anyone has a 
klnown-good dump of the 2564 in an MW4, I'd be interested...

-tony