How to power off the ZX81 correctly

[AN7805]

Hi at all,

i ask a doubt i have;

how to power off correctly the ZX81?
From mains AC or cut down directly from the power jack?
Where is the most " soft" power off for the Power brick, and the microcomputer?

Thanks at all,

Matt

[XavSnap]

I use to remove the jack 2-3 seconds… and i plug-in it again.
While this process, the RAM pack can move, and freeze the CPU !

Always put the rubber stick under the zx case, to avoid to shake the extension board while pressing a key or insert the jack.

[AN7805]

Thanks Xav;

Same procedure with power on?

Greetings,

Matt

[1024MAK]

how to power off correctly the ZX81?
From mains AC or cut down directly from the power jack?
Where is the most " soft" power off for the Power brick, and the microcomputer?

It does not really matter. You can either disconnect the mains or the low voltage 3.5mm power jack plug.

To power up, again either method can be used. However, as Xav points out, when powering on by connecting the 3.5mm power jack plug, hold the socket firmly so that the ZX81 does not move. Otherwise if using a memory expansion (RAM pack) or other expansion, the vibration / movement may cause a wobble and result in a crash. Then you have to try again

Some members have connected a in-line switch (like used on table lamps) into the low voltage cable. Or use a ready made in-line switch (these are available with 2.1mm/5.5mm barrel connectors) and suitable 3.5mm to 2.1mm/5.5mm barrel adaptors.

Mark

[AN7805]

Thanks Mak.

Now it is clear for me.

Matt

[Paul]

I have a switch at the 230V line.
If a "not so good" power supply is used without load it can go quite high with the voltage. Then the "stress" to the Zeddy (and extensions) 5V circuit is higher than necessary.
Building up the transformer voltage with the Zeddy plugged in (having a load) these peaks in voltage are avoided. Powering down either way doesn't matter.
This experience comes from Spectrum internal RAM failings when switching the low voltage instead of high voltage. This precaution can't be wrong with a ZX81 as well.
Kind regards Paul

[PokeMon]

Always this way PRINT "SHUTDOWN IN PROGRESS" - wait 5 seconds and pull the 3.5mm plug out.
Be sure to wait at least 5 seconds to get the heads of the ULA in park position.

Funny question by the way - you made my day.

[1024MAK]

Always this way PRINT "SHUTDOWN IN PROGRESS" - wait 5 seconds and pull the 3.5mm plug out.
Be sure to wait at least 5 seconds to get the heads of the ULA in park position.

Will you get a blue screen of death if you don’t follow this advice

Mark

[siggi]

I recommend to use the following shutdown program:

Code: Select all

call FAST
HALT

Then you can pull the plug ...


Siggi

[XavSnap]

True…

Code: Select all

10 FAST
20 RAND USR 0
30 PRINT "SHUT THE POWER DOWN VERY QUICKLY..."
40 PRINT "TOO LATE IF THE K  IS BACK"
50 PRINT "RETRY PLEASE"