27 Dec
2005
27 Dec
'05
12:01 p.m.
On Tuesday 27 December 2005 08:20 am, Tony Duell wrote:
The wedge has a socket, too.
Connect a _reguylated 5V PSU_ (nothing else) to the battery connector
inside. I mentioned where to get the sockets in an earlier message, you
can get the polarity from the technical manual or by examining the NiCd
pack.
I *made* that pack, the one that came with it was shot. I also used to run a
retail battery store, and salvaged a whole bunch of similar connectors from
cordless phone batteries that folks brought in for replacement, and I'm sure
that one of those will work.
A regulated 5V supply should be no problem for me.
I don't
think this one has BASIC in it. There are eproms, Portable
WordStar,
Probably not if you have wordstar. There are only 2 EPROM sockets, BASIC
fills an EPEOM, I think wordstar would as well. The EPROM you really need is the utilities one.
Without it, you don't
have PIP, and therefore no way to copy files.
I think nsweep might be in there, though I'm not sure, it's been too long.
From memory, a PX8 has the following connectors :
A coaxial power connector for the charger
An 8 pin mini-DIN 'serial' port for the disk drives. It can also be used
for a printer, but only at a cery limited selection of baud rates. It is,
at least, at RS232 levels. Only 5 pins are wired (ground, TxD, RxD,
handshake out, handshake in, the latter being on the pins used on the
RS232 poer for DTR and DSR).
An 8 pin mini-DIN 'RS232' port All pins usedm you get the normal
hardware handshake lines.
A 3.5mm stereo jack socket (like a 'walkman' headphone socket) 'BCD'
port. This is for a BarCoDe reader, the connections being ground, signal
and +5V power out from the PX8. From what I can see the signal goes both
to one channel of the ADC chip and to a pin on one of the gate arrays
which contains logic to measure the time between transitions of the
signal. Note there's no barcode software in the BIOS ROM
Sounds about right.
Another 3.5mm jack socket 'ADC In'. This is an
analogue input to another
channel of the ADC chip, the other connecitons being ground and a
TTL-level trigger signal
It'd be nifty to see if I can find some use for them, once I get it working.
A 3.5mm mono jack socket 'SP out' for an
external loudspeaker.
A 50 pin header 'System Bus' which is essentially the unbuffered Z80 bus
lines.
I think that's what the wedge connects to.
You can turn it off with the little switch inside the
main batter
compartment. The machine should run from the main battery (or a 5V PSU
connected in place of the main battey) if there are no otehr problems.
To the battery connector? Ok... I will emphasise this again because it's
important. There is no regulator
circuit between the battery and the standby supply line (maintains RAM,
real time clock, etc when the machine is turned off) or, indeed the main
logic supply line. Do not connect an unregulated supply here, you will
wipe out chips throughoug the machine.
The wall-wart is an unregulated thing. Claimed to be 6V 600mA on the
label (and in the manual), in reality it's nearer 12V off-load. This
charges the main battery, and the machine depends on the fact that the
the battery will clamp the voltage to 4.8V or so to limit the voltage on
the logic supply lines. Do not, I repeat, use that PSU in place of the
battery, do not, in fact, plug it in without as good battery in place
(there is a proteciton zener diode, but I don't trust it!)>
Hm.
Do
remember there are no regulators in the PX8 PSU. The power supply
must be close to 5V (4.8V is OK), not a random unregulated one. You may
well do a lot of damage with the latter.
Are you talking about going right into the battery input connector? Or
to the charger input on the rear of the machine? The "power supply" I
use with it is a wall wart, I don't recall what it's rated at, but it's
labeled with that dymo tape stuff as being for that machine, came with
it when I got it. I run mine from a regulated electornic workbench
supply connected in
place of the battery (and set between 4.8V and 5V). I would think the 5V
supply from another computer would be OK (e.g. an old PC power supply),
but I've not tried it, so don't blame me if you kill all the ICs in the
PX8...
I have enough 7805s and similar to deal with that, for sure.
--
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"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin