Another quick break
29 May 2024 | 10:00 pm

Taking leave again for a bit to sort out some big things, and smell the flowers. Thanks everyone, and catch you soon. 👋 💐

By Ruben Schade in Sydney, 2024-05-30.


Stymied by a 1990s thermostat
27 May 2024 | 10:11 pm

Spend time in an Australian apartment or hotel room built during a specific time in the late 1990s, and chances are you’ll come across a thermostat panel that looks, a little something, like this:

A minimal thermostat showing a tiny 2-digit LCD and a few buttons.

(The bezel hasn’t yellowed, the whole apartment has that beige/cream accent everywhere).

This is the unit that controls our reverse cycle air conditioner, also known as a heat pump in North America. It’s been a continual source of frustration since we first moved in, to the point where it still surprises me two years later.

So it’s time to play a game; I know you all love these! Wait, where are you going?

For your first question, take a look at the panel. Say I’ve tasked you with turning it on, and setting the heater to 23 degrees. What buttons would you press? Take your time, look at the buttons and have a proper think.

I know my readers are intelligent, rational, and above all attractive people, so I can anticipate your response. You probably said that you should press the On button to turn it on, followed by pressing the Up arrow to increase the temperature. Right?

Wrong! Don’t fret though, Clara and I made the same mistake.

It’s a fair assumption. Every other air conditioner remote control and thermostat I’ve ever used operates this way. It also makes intuitive sense: you press the Up arrow on a thermostat for more warmth, and the Down arrow to make the room cooler. Except, no!

This leads to the inevitable second question. If pressing the On button, then the Up arrow doesn’t increase the temperature… what does it do? These were the responses from a straw poll at work:

  • Increase the fan speed

  • Toggle the mode from auto (the default), heat, or cooling

  • Spring out a rubber chicken

None of these were correct either.

Give up?

It tells you the current temperature of the room.

I want everyone to take a moment to appreciate this. You press the On button, followed by an Up arrow, on a thermostat, and it… tells you how hot or cold the room is.

If that sounds ridiculous, it gets even worse. Pressing the Up button doesn’t just tell you the current temperature of the room, but it blinks every other LED on the entire panel along with it. You’re being told the aircon is operating in cool mode, warm mode, and auto mode, and the fan is set to low, mid, and high. Concurrently! It’s inscrutable to a layperson, and looks like a crash or a bug to an engineer, because it looks like it’s broken. At what point would it make sense for a fan to be spinning at three speeds at the same time!?

Consulting the horribly-written manual from reception downstairs however, and this is expected behavior. There’s a truth table that indicates the temperature sensor output is being displayed if all the LEDs are on. If another nonsensical subset of the LEDs are on, it means certain other things. And so on.

This gets to the core of the issue here. Because the people who designed, built, and sold the panel were too cheap to include a single extra button called “sensor” or “room temp”, they had to have the feature invoked by pressing a sequence of other buttons. A sequence, mind you, that not only makes no sense, but is apparently so integral to the system’s operation that they were willing to replace a core feature with it. Namely, setting the temperature on a thermostat. It boggles the mind.

If you’ve made it this far, you know what the third question is going to be. If On and Up doesn’t turn the aircon on and turn the heat up, and instead shows the temperature of the room… how do you turn the aircon on and turn the heat up? Any guesses?

The answer is only slightly less ridiculous. You have to press the Up button and hold it down for more than a second. Again, you don’t just press it like you would any other switch panel or remote control made across the ages, you have to keep it pressed. This is not written anywhere on the device.

Why is this bad, besides it being completely unintuitive, and subservient to another feature that’s almost completely useless? Well, if you have a range of temperatures to scroll through, you can’t just rapidly press the button. No, you have to hold it down and wait for it to count up or down. Slowly. Eventually! 21… 22… 23…

This panel has a few other fun tricks. There’s a secret admin mode you can easily invoke by accident with another combination of buttons that can be used to set the upper and lower temperature bounds, which can lead to situations where it’s the dead of winter and you can’t go above 18 degrees, or summer where you can’t go below 24, requiring a tech to come out to reset it. Always fun!

We’re in the process of moving, so we won’t have to put up with this silly thing for much longer. Maybe. We hope!

By Ruben Schade in Sydney, 2024-05-28.


The SPAOE Z80 Apple II card
27 May 2024 | 10:07 pm

Ever since I found out you could get a Z80 card for the Apple II, I’ve been researching every option I can find. They broadly come in two flavours: the Microsoft Softcard which shares the host Apple II’s memory, the PCPI AppliCard which acts like a single-board computer… and more clones of each than you can throw a CP/M disk at.

The SPAOE-Z80 is the one that’s intrugied me the most. It’s by far one of the more common Softcard clones you see on second-hand sites, yet there’s scant information about it. eBay listings regularly misspell the name, or omit it entirely in lieu of calling it a Z80 Card or similar. There’s an inconveniently-placed trace that sits underneath the sinkscreened name that either obsscures the O or E, which only adds to the confusion.

MG’s Apple II Site lists it as a “Generic Softcard clone”, and links to a photo on the Apple II Documentation Project:

Photo of the SPAOE Z80 card.

It looks like a generic Microsoft Softcard clone, but is it? This old newsgroup thread from 2019 started by Bobbi hints that it is:

The CP/M card is a from SPAOE, whoever they were! I think it is pretty much a generic clone of the Microsoft Softcard. […] Incidentally, my SPAOE Z80 Card looks identical in layout to the Pineapple one Anthony posted a pic of yesterday. Looks to be a complete clone of the real Softcard.

I got DATASOFT CP/M 2.23B to boot (63K TPA)

Bobbi also opened an issue on the ProDOS8-Testing repo with the card around the same time. Olivier Dauby also mentions finding a SPAOE-Z80 card in their Apple //e, but only in the context of identifying an unrelated disk controller.

The photo above shows a first-party Zilog Z80A, though eBay archive site WorthPoint shows an old listing with Sharp silicon instead. I suspect swapping out Z80 suppliers was fairly common.

That’s about all the information there is about this card. Archive.org lists nothing, and web searches only return space agencies. I suppose clone cards weren’t unique enough to justify coverage; probably by design.

By Ruben Schade in Sydney, 2024-05-28.



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