At 40 (HAPPY BIRTHDAY SPECCY!) – How Many Types of Sinclair ZX Spectrum Are There?

A PopeyMon Customer’s Sinclair ZX Spectrum Cassette Player and Joystick Interface Bundle


Today, on St. George’s Day 2022, is the 40th Anniversary of the release of the Sinclair ZX Spectrum computer. It is a happy day to celebrate the Spectrum but a day also tinged with sadness after the death of the great British inventor and entrepreneur Sir Clive Sinclair in September 2021.

The Sinclair ZX Spectrum has been a very successful machine and has spawned thousands if not millions of British and international careers in information technology, games and other industries.

The Anniversary is being celebrated with an event at the National Museum of Computing at Bletchley Park. Sir Clive’s son Crispin will be attending.

40 years later, there is a thriving Spectrum scene with new games and software being released, repairs and refurbishments being done (including here at PopeyMon) and new models of Spectrum hardware with two new versions of the Spectrum Next.

And from conversations with customers, it is great that parents and grandparents are encouraging their friends and families to discover the wonders of the Spectrum rubber-keyed wonder.

I am often asked – how many types of Sinclair ZX Spectrum are there? And what are the differences and similarities between them?

So to commemorate the 40th Anniversary, I have written this article to answer these questions, with a (generally) chronological order of release of each model of Spectrum. Brief details of each model are given. The article is not meant to be exhaustive in technical detail. That will require more detailed articles on each model. There is a Glossary at the base of the article.

The Sinclair Era of Spectrum and The Amstrad Era of Spectrum

Broadly, the models of Sinclair ZX Spectrum fall into two categories – Sinclair-era and Amstrad-era. When Sinclair ran into financial difficulties, caused mostly by the Sinclair C5 and QL commercial failures, Alan Sugar’s Amstrad bought the Sinclair computer brand in 1986. I break the models of Spectrum into these two eras. And now there is a new era, of the Spectrum Next. This article does not discuss the Next.

In 1982 when it came to home computers in the UK, it was clear from the industry and from his biographies that Alan Sugar was The Apprentice and Clive Sinclair the Master. The Spectrum far outsold the Amstrad CPC in the UK and Sugar came into home computers when the Spectrum had already been established.

And the Spectrum and Amstrad computers would prove to be inextricably linked over time. Both would have varying successes in different parts of the world.

The Sinclair Era of Spectrum 1982-1986

The Rubber Keyed Wonder – the 16k and 48k Spectrum

The Rubber-Keyed Wonder

It all started with the rubber key model that was released 40 years ago today, on 23rd April 1982. This was called Issue 1.

Before its release, the Spectrum had also been called the ZX82. Its predecessors were the ZX81 and ZX80. Sinclair’s Mark 14 computer could also be called another Sinclair ancestor of the Spectrum.

In a nutshell, the Spectrum is a Z80 CPU-based microcomputer with a custom ROM implementing the Sinclair BASIC operating system and assisted by a Ferranti ULA chip. It could be viewed the other way around, with the ULA being the beating heart of the Spectrum.

The Spectrum ULA deals with input and output including:

  • the RF display output to UHF Channel 36 on a domestic TV
  • the rubber keyboard with membrane and
  • using cassette tape for loading and saving programs to an external tape unit.

The Spectrum came in 16k RAM and 48k RAM models. The 16k could be upgraded to 48k at a later date. There was a special board at first for the Issue 1 board and eventually with the Issue 2 board, it could be done with the addition of 8 upper RAM chips and two wire links on the board.

I offer the 48k upgrade service in the PopeyMon Webshop. I can also reverse the process for you, if you want to revert a 48k Spectrum back to 16k.

There were 8 revisions of the board inside the rubber key case:

  • Issue 2
  • Issue 3
  • Issue 3B
  • Issue 4A
  • Issue 4B
  • Issue 4S
  • Issue 5
  • Issue 6A

Each issue made changes to the printed circuit board (PCB) design and added, removed or modified some components.

The power circuit that creates the voltages needed for the Spectrum from the external power supply unit (PSU) proved to be unreliable and 40 years later still causes many problems for Spectrum users. This DC-DC conversion circuit was tweaked but remains problematic 40 years later.

In the PopeyMon Test, Assess and Repair service that you can buy in the PopeyMon Webshop, it often comes up during testing and assessing as the cause of problems with my customers’ Spectrums. I have written an article on the common problems with the Spectrum – the keyboard membranes also dry out and need replacing. I can also supply and fit them for you.

The Spectrum +

The Sinclair ZX Spectrum +

The Spectrum case and keyboard did not change until the Spectrum + model which was released in 1984. The Spectrum + had the same board but put inside a new black case with hard keys, some extra keys and a slightly different layout. It also had spring-loaded legs and a reset button fitted inside.

Any Issue board from the rubber key model can be fitted inside the Spectrum + case. It is the same board.

The 128k Spectrum – a.k.a. Toastrack

The Sinclair ZX Spectrum + 128K

The next model of the Spectrum was the Sinclair ZX Spectrum + 128k, shortened to the “Toastrack” due to the huge black heat sink protruding from the right-hand-side of the case.

Other than the heat sink, the case is very similar to the Spectrum + case with the keyboard and membrane being identical to the Spectrum + and with the same reset button.

As well as adding RAM, there were other changes to the software and hardware that included:

  • a new AY-3-8912 sound chip
  • RGB TV output as well as the traditional RF
  • a MIDI music port
  • a new ROM and menu system allowing 128k and 48k modes, plus tape Loader and Calculator options on the menu

The Amstrad Era of Spectrum From 1986 Onwards

The Sinclair 128k ZX Spectrum +2 (Grey Model)

The Sinclair 128K ZX Spectrum +2

When Amstrad took on the Spectrum, they hastily produced an Amstrad flavour on the Toastrack theme. They used the case design and philosophy of the Amstrad CPC 464 and added a built-in Datacorder to the case and a “proper” full keyboard. The new model looked like a CPC 464 but was essentially a Toastrack Spectrum inside.

With deadlines looming, commercial decisions were made to add features with a typically Sugar-esque flavour. Some of these would prove to be very annoying to users of the Sinclair-era Spectrum models then and now.

  • manufacturing was eventually to be moved from the UK and go to Taiwan with the Grey +2 and eventually China with the Black +2. The early issue Grey +2 was made in the UK with the later production moved to Taiwan.
  • joystick ports were added although to an Amstrad standard not the Atari standard
  • printer port was added
  • RS232 and AUX ports were added. The AUX port could be used with a light gun.
  • RGB output was retained
  • MIDI port was retained

Only minor changes were made to the ROM such as the copyright and menus.

The Black Tape +2 Model and +3 Disk Model

The Sinclair 128K ZX Spectrum +2 (Black Model)
The Sinclair 128K ZX Spectrum +3

This was a radical re-design of the Spectrum with a dark grey/black case instead of the Grey +2 case. As with the later versions of the Amstrad CPC computers, the number of chips would be reduced.

The interfaces remained the same, but the board inside was a complete re-design of the 128k Spectrum PCB. A new Gate Array chip would be soldered “in a hole” on the new Spectrum board, and not using through-hole soldering. The Amstrad 40077 part number was allocated to it and it was primarily this 40077 IC that allowed the reduction of chips.

There was a tape (Datacorder) model, the +2A and also a 3 inch disk version, the +3. Again, the Amstrad CPC computer had its influence on the Spectrum. The CPC 6128 also had a 3 inch disk drive.

The re-design also removed the notoriously unreliable power (DC-DC conversion) circuit. A large power brick would be used instead, like the later Commodore Amiga and much later Microsoft Xbox power suppllies. The required voltages would be generated inside the PSU now, and not on the new Spectrum PCB.

With a re-design there are inevitability compatibility issues. While these are limited, they do cause issues with a very small number of programs.

There were later revisions of the Black +2 and +3, being called the +2B and +3B.

By then, production had been moved by Amstrad to China.

Production of the Spectrum ceased in the early 1990s.

I offer services for ALL models of Spectrum in the PopeyMon Webshop. I also sell parts.

Please browse the PopeyMon Webshop and get in touch if you have any questions or are looking for a bundle of Spectrum goodies.


Finally, to answer the question in the title of the article…

According to the definitions of model that I have used in this article, there are…

SIX models of Sinclair ZX Spectrum over two eras.

  • rubber keyed 16k/48k
  • Spectrum +
  • 128k Spectrum “Toastrack”
  • Grey +2
  • Black +2A/+2B tape model
  • Black +3/+3B disk drive model

But technically, there are other ways of looking at the question, so like the very large computer Big Thought in Douglas Adams’ Hitchhikers’ Guide to the Galaxy, the answer (42) depends on (being more specific in) the question.

This article is just one Spectrum fans’ view and classification, after all. You could say that there is only one type of Sinclair ZX Spectrum – the Spectrum! šŸ™‚

I hope that you found the article interesting and informative, and this will encourage you to buy products and services in the PopeyMon Webshop and PopeyMon eBay Shop and read more articles on the PopeyMon website.

Happy Spectrum-ing to all!


CPC Amstrad Colour Personal Computer
DC Direct Current of electricity
IC Integrated Circuit chip
MIDI Music Industry Digital Interface
PCB Printed Circuit Board
PSU Power Supply Unit
RAM Random Access Memory
ROM Read-Only Memory
RGB Red-Green-Blue standard for computer displays
ULA The Ferranti Uncommitted Logic Array integrated circuit chip

What Are The Common Problems With The Rubber Key Sinclair ZX Spectrum and Spectrum +?

The Rubber Key Sinclair ZX Spectrum

In 2022, the Spectrum will be 40 years old. It was originally released on St. George’s Day, 23rd April in 1982.

So what are the most common problems with the first two models? This article looks at four of them:

  • The Keyboard Membrane
  • The TV Display
  • The Electrolytic Capacitors and Power Circuit
  • The Spectrum will not boot to the white screen and Sinclair Research prompt

Before we start, please be aware that I offer a basic test, assess and first hour of repair service. If it takes longer, then I will let you know my assessment before doing any further work. This service is available for all models of Spectrum, and at the same cost – click here for more details.

Let me know what you are looking for, by getting in touch via the Contact form or contact details at this link here. I give discounts if you buy a bundle of products or services.

The Keyboard Membrane

A New and Old Keyboard Membrane on a Sinclair ZX Spectrum + (Plus)

By far the most common problem on a Sinclair ZX Spectrum and Spectrum +, is the keyboard membrane. You might be able to get the Spectrum to display the Sinclair Research prompt (see below), but the keyboard may not work at all, or some keys work and others do not.

This is because the keyboard membranes dry out, become brittle and fail with age. It is rare to find an original one that is fully working these days*. And if the membrane is working at first, it will probably not be long before it starts to fail when the Spectrum is started up again, with some keys not working or the ribbons breaking connections with the Spectrum’s printed circuit board (PCB). The ribbons may break when you open up the Spectrum.

In the first photo above of inside a Spectrum + case, the old membrane is shown on top of a new one. The new one has been fitted to the top of the Spectrum + case. The new one is shiny. The old one is dull. The second photo below shows the completed process of fitting the membrane.

The new membrane fitted to the Spectrum +

At PopeyMon, I offer a service to source and to replace faulty membranes with new ones and to service the keyboards on the later models of Spectrum. There is a service that I provide for each model of Spectrum here – click the link:

*There is one exception – those produced by Samsung were higher-quality and last longer. But even these can fail and must be checked.

This procedure is particularly tricky on the Spectrum + and on the Toastrack to get right, and to make sure that all keys are working. The membranes are also more expensive than for the rubber key models. And hence the price difference with the service between the rubber key and +/128k. A photo of the new membrane for the rubber key, being fitted for a PopeyMon customer during a full repair and refurbishment, is shown below.

New Keyboard Membrane

While I have your Spectrum, I can also perform other repairs and refurbishments. Read on for more.

The TV Display

A Sinclair Spectrum Running Manic Miner on a Modern TV using Composite Video TV Signal

Another common problem is that when the Spectrum was brought out, it was common for home computers (called “microcomputers” back then) to use the domestic TV to output their display, and to not use monitors.

TVs in 1982 used an analogue radio wave signal, which was normal for broadcasting TV in those days. There was no digital TV signal. And the TVs were cathode ray tube (CRT) designs.

So inside the Spectrum, there is a modulator box that converts the Spectrum display to Channel 36 UHF (Ultra High Frequency).

But in 2022, this is a problem because modern TV designs do not use CRTs. And the analogue TV signal has been replaced with a digital TV signal.

If you have an old TV, this is not such a problem. But CRTs are getting old and can cause problems with reliability and safety. They are high voltage and high current.

Some modern TVs allow you to easily tune to analogue signals. Others have a complicated menu system to navigate. And other TVs don’t allow you to even tune in to analogue at all.

Modern TVs also expect certain characteristics of the signal from the old computers and the computers just cannot live up to the expectations.

So while you can do it “the old way”, it is advisable to use the composite video signal that was always generated by the Spectrum and then converted by the RF modulator. You just ignore the RF output and by-pass it.

The composite video modification is another service that I provide at PopeyMon. You can buy it from the shop by clicking here.

The Electrolytic Capacitors and Power Circuit

An Issue 3B Spectrum PCB Repaired and Refurbished by PopeyMon

A common problem in old electronics is that electrolytic capacitors can fail. Age, storage conditions, usage patterns, heat and other factors can mean that they can dry out and deteriorate from their function of storing charge. This can impact on the performance of other components in the Spectrum, and even stop it from working completely.

Of particular concern inside the Sinclair-era models of Spectrum is the DC-DC conversion power circuit on the right-hand-side of the PCB in the photo above. This power circuit is notoriously unreliable and has caused many repairs to be done. It has also damaged other components, such as the lower RAM chips that are required for the system to start successfully to the Sinclair Research prompt.

The power circuit was revised and revised again in later issues of Spectrum PCB. When Amstrad took over the Sinclair brand, it was removed completely from the Spectrum PCB and put in an external PSU.

This wise decision by Amstrad did not solve all of the issues in the later models of Spectrum, but it solved some of the problems on the computer PCB. I have other articles on this website about the models of Spectrum and a whole series of article about the PSUs. I also sell all models of Spectrum and PSUs in the PopeyMon shop.

Why have I mentioned the power circuit in relation to the electrolytic capacitors? Because the power circuit is essential to the operation of the booting of the Spectrum. If the power circuit is not producing the correct voltages, then your Spectrum will not start up properly, if it starts up at all.

So if the capacitors in the power circuit are failing, then this can mean that the power circuit is not working correctly and your Spectrum fails. It can damage components that are particularly difficult to replace.

It is therefore wise to perform checks before starting up a Spectrum. I can perform these checks and more for you, when you send me your Spectrum.

I offer a service to replace all electrolytic capacitors with brand new and quality new ones – click here. While this may not fix all types of problems, it can prevent some problems from occurring now and in the future.

The Spectrum Doesn’t Boot to the Sinclair Research Prompt


If the Spectrum does not start up to the white screen and Sinclair Research prompt, then there is a problem. When the Spectrum starts up, it performs a self-test and if the test is successful, you get the prompt. Possible causes could be the power circuit as described above. It could also be a host of other problems. If you cannot get all keys to work, then it is probably the keyboard membrane, as described above. If you cannot get a TV display, then the section above describes possible causes.

I offer a basic test, assess and first hour of repair service. If it takes longer, then I will let you know my assessment before doing any further work. This service is available for all models of Spectrum, and at the same cost – click here for more details.

Let me know what you are looking for, by getting in touch via the Contact form or contact details at this link here. I give discounts if you buy a bundle of products or services.

Thanks for coming to PopeyMon Games and Fun for all your Spectrum needs.

How Many Sinclair ZX81 Power Supplies Are There?

Two Designs of the ZX81 PSU

This is another article on Sinclair power supply units (PSUs) in the PopeyMon Games and Fun series of articles. This one is on ZX81 PSUs. I have another set of articles on ZX Spectrum power supplies for all models of the ZX Spectrum.

There are at least two types of ZX81 power supply. There may be more, but I have not come across any more than just the two in the photo. If you know of others, please get in touch:

  • the UK700, which can deliver a maximum of 700mA (0.7A)
  • the UK1200, which can deliver a maximum of 1200mA (1.2A)

In the photos above, there are two different designs of the ZX81 PSU. On the left is the UK700 and on the right is the UK1200.

The cases of both UK700 and UK1200 are the same. The UK1200 for the ZX81 is almost identical to the Spectrum UK1200 that I show in one of the Spectrum articles. It uses a different connector, so extra care must be taken to check polarity. I have also not tested this out, so please do not do this unless you are sure what you are doing.

The capacitors and the circuits are quite different.

The UK700 does not have four separate diodes to create the full wave bridge rectification. It uses a special component and has two smaller 1000 uF capacitors. No fuse is visible on the mains side of the transformer, although this may be hidden.

The UK1200 has four diodes for the rectification, and one larger 2,200 uF and one smaller 1,000 capacitor. The fuse is visible on the mains side.

The UK700 may struggle if you are using peripherals with your ZX81 that use more current than the ZX81 on its own, but the UK1200 should be able to handle peripherals better.

I have used both the Sinclair 16k RAM Pack and the Memotech 16k RAM Pack successfully with both the UK700 and UK1200.

But I would be concerned as to whether the UK700 would be able to deliver the current for a ZX Printer. The UK1200 would be preferable. I have yet to test this though, as I don’t have a working ZX Printer.

Please see the warning below about the dangers of power supplies. Even those that deliver low DC voltages to the computer, still involve mains voltages which can kill.


In any case, whether you do understand or not, it is wise to check the safety of any PSU before use. Why?

Because unless you have owned the PSU ever since buying it, you may not know what has happened to the PSU since it was manufactured. It may have been looked after in the original ZX81 polystyrene and box, and lovingly cared for during the last 35-40 years.

Or it may have lived in a damp cellar, being damaged in bad conditions and affected by temperature variations and damp. It may have even been dropped from a great height onto a stone floor. Or dragged along tarmac by your delivery courier.

You just don’t know!

So unless you know what you are doing, please seek professional help to check.

PopeyMon Games and Fun has refurbished and sold many ZX81 and Spectrum PSUs.

Please get in touch and we can provide a refurbished power supply or repair yours.

Thanks for coming to PopeyMon Games and Fun.

Sinclair ZX Spectrum Power Supplies – What Types Are There (Part 6)? – The First One? UK1200?

When I started doing the research, opening up lots of Spectrum power supplies, and writing this series of articles, I had thought that the UK1400 power supply was the first one for the Spectrum, as shown below.

Power Supply for Rubber Key and Plus Types of Sinclair ZX Spectrum

But I was told by members of the Spectrum community that there was a UK1200. I had never seen one in the flesh… UNTIL NOW!

I have got one NOW! How exciting!

Model name: UK1200

Input: 240V AC

Output: -12.5V DC approx., unloaded (unregulated), maximum current rating 1.2A (1,200mA and hence the name UK1200).

When under load and being used on a Spectrum, the voltage will be nearer to what is stated on the PSU label.

Polarity: Centre Negative (not positive) Outer Positive (not negative as on most barrel connectors).

Getting the polarity is essential if you do not want to damage your Spectrum.

I do not know whether the UK1200 power supplies are suitable for any other model of Spectrum than the Issue1 Spectrum.

The strain relief on the PSU is not as stiff as on the UK1400. This might mean that it lasts longer because they are notorious for breaking.

It has a barrel connector that is not smooth. The UK1400 that was subject to a safety recall had a smooth barrel and black and white DC cable.

The insides are very similar to the UK1400. It is a full wave bridge rectifier with two smoothing capacitors. And a fuse.

I cannot verify that it the UK1200 would work on an Issue 1, because I do not own one.

However, the fact that the UK1400 power supply followed the UK1200 – or even possibly was being sold at the same time as the UK1200 – suggests that 1.2A was insufficient for the Spectrum and 1.4A was needed.

The UK1200 certainly won’t be suitable for the 128 “Toastrack” and not the (Amstrad-era) Spectrum +2 Grey. This is despite the fact that the DC (computer side) barrel connector will fit on these later models of Spectrum.

I would not recommend running any Spectrum with the UK1200 and without an Issue 1, I have no intention to!

And sorry. This power supply is not for sale.

But I do have a range of other power supplies for sale. The series of articles on this website is there to help you choose the right one.

Before use all power supplies need to be checked for safety, as well as functionality and that they are delivering the right voltage levels, current and polarity. So please note that they must be checked before use, and check the Safety article.

If you are looking to buy any power supply or want one checked, please get in touch. I will happily sell you one – fully tested and working – for the Spectrum 16/48k/Plus, for the grey +2 or the black +2 or +3. I also have a lot of other Spectrum parts, working computers and games for sale. I will happily put together a custom bundle for you.

I would like to credit and highly recommend the excellent videos by “JoulesPerCoulomb” on Youtube. “Greetings and good time of day…” to whoever this mysterious but extremely helpful man, is. His video on power supplies was a brilliant starter a few years ago to the many hours of research that I have conducted since on Spectrum power supplies, and which I present in this series of articles.

A Look Inside the Original Spectrum Power Supply (16/48k Rubber Key Models)

The UK1400 PSU
The UK1400 Power Supply Unit (PSU)

On this PopeyMon Games and Fun website, in a series of articles I have tried to described all types of power supply unit (PSU) for the Sinclair ZX Spectrum models.

This goes from the first 16k and 48k rubber key models when the Spectrum was owned by Sinclair to the final disk drive version of the Spectrum, the +3 under the ownership of Amstrad. There is an index to the articles, as Part 0 of the series.

In this article, I am delving into the inside of the original Spectrum power supply, the UK1400 model.

I say original, but I’ve been told from several credible sources in the Spectrum community that the Issue 1 Spectrum had a UK1200 model. Until I see one being used on an Issue 1 Spectrum “in the flesh”, I will still call the UK1400 the original Spectrum PSU.

The UK1400 was used for all rubber key models of the Spectrum – 16k and 48k. It was also used on the Spectrum Plus with a different design.

This earlier article also talks about the UK1400. But I want to go a bit deeper here. Here are six images of the components inside the UK1400. As in the earlier article, there are several designs of the UK1400.

They are all implementations to the same specification. And all of them use a full-wave bridge rectification circuit to convert the mains 240V into around 12-14V DC (unregulated and when unloaded) via a barrel connector to the Spectrum board.

Note: A “smooth” barrel connector has been used to replace the original on the photo at the top of the article. Please see the Safety Warning article for more on the UK1400 production that were recalled for safety issues.

Each of the designs meet the UK1400 PSU Specification in different ways.

Some designs are compatible with other designs and some are not.

There are different orientations of the PCB and transformer – some designs have the PCB underneath the transformer and other designs have the PCB at right-angles and to the side of the transformer.

There are different versions of the case, so they are not interchangeable with different designs. Here is one case from a PSU that failed its tests.

And as I have said on other articles, BEFORE you plug any power supply into your beloved Spectrum, please CHECK is it safe to use: (i) for you, (ii) for your Spectrum.

I have TESTED and WORKING PSUs for sale in the PopeyMon website shop and in the eBay popeymon shop too.

If you have any questions, please get in touch.

How Many Sinclair ZX Spectrum Power Supplies Are There?

Two Designs of the UK1400 PSU

This is another article on Spectrum power supplies in the PopeyMon Games and Fun series of articles.

In the photo above, there are two different designs of the UK1400 power supply unit (PSU). This was for the 16k and 48k rubber key Spectrums. As described in more detail in Part 1 of the Series and Part 3 of the Series, the UK1400 can also be used on the Spectrum Plus.

In the photo are two similar designs. But they are not identical. Can you spot the differences?

Spectrum UK1400 with Transformer on Top

Several other designs also exist, including designs where the transformer is on the top of the PCB, instead of next to it (see photo).

The cases can also differ on the inside, meaning that different designs may not be interchangeable. There are also variations in the capacitors, in the number of capacitors and even the polarity of the wires to the DC cable can be swapped, with respect to the colouring on the wires.

So what seems to be the same PSU from the outside, can be quite different on the inside.

Unless you have owned the PSU ever since buying it, you may not know what has happened to the PSU since it was manufactured. It may have been looked after in the original polys, and lovingly cared for during the last 35 years. Or it may have lived in a damp cellar, being damaged in bad conditions and affected by temperature variations and damp. It may have been dropped from a great height onto a stone floor.

You just don’t know!

And there is also the official Sinclair Safety Warning for one of the designs to consider, as described in this article here.

So using and tinkering with power supplies can put your Spectrum and more importantly, your health and safety, AT RISK!

You should check your power supplier is the right one, and that is safe for you and your Spectrum.

So unless you know what you are doing, please seek professional help.

PopeyMon Games and Fun has refurbished and sold many Spectrum PSUs.

Please get in touch and we can provide a refurbished power supply or repair yours.

There are more types of Spectrum PSU:

Please click on the links for more info on each power supply, and which can be used with each model of Spectrum. The general advice is that as each Spectrum was released, the power requirements increased. So earlier PSUs tend to NOT be compatible with later Spectrum models. In any case, the power connectors changed on the Black +2 and +3.

Thanks for coming to PopeyMon Games and Fun.

Spectrum +2 (Black) PSU

Sinclair ZX Spectrum Power Supplies – What Types Are There (Part 5)? – The +3 (Disk Drive Spectrum)

The Sinclair ZX Spectrum +3 (Black)
No Tape but Floppy Drive Instead!

There are several types of Sinclair ZX Spectrum. So it follows that there are several different types of power supplies for the Sinclair ZX Spectrum.

This ranges from the rubber key 16k and 48k models, then Plus and 128 models during the Sinclair ownership of the Spectrum brand, through the Amstrad ownership of the Spectrum brand (after Alan Sugar’s Amstrad bought the rights to the Sinclair Computer brand), to the present with the new Spectrum Next.

Part 1 of the PopeyMon articles on the types of Spectrum PSU talked about the rubber key models and the Spectrum Plus.

Part 2 dealt with just the Spectrum 128 (“Toastrack”).

The Amstrad-Owned Era of the Sinclair ZX Spectrum

Part 3 dealt with just the Grey +2.

Part 4 dealt with the Black +2 (+2A and +2B).

Part 5 deals with the +3, the disk version of the Spectrum.

Like the Grey +2 and the Black +2 – although the case is similar to the Amstrad CPC, the power still comes from an external power supply. On the original design of the CPC, there was only one plug, for the monitor and computer. The power for the computer came from a lead that went from the monitor to the CPC. There was only one plug.

The +3 has one plug for the computer unit, but you still need a plug for your separate display.

Power Supply for Rubber Key and Plus Types of Sinclair ZX Spectrum

The Black +3 PSU could be referred to as a “power brick”, like the Xbox 360 PSU. It is very heavy. It generates the voltages on different lines to a DIN connector, instead of the barrel connector used for the UK1400.

The +3 PSU is much larger than the earlier Spectrum PSUs. The voltages and current rating are shown in the photos above, and described below.

It generates:

  • +5V at 2A
  • +12V at 700mA
  • -12V at 50mA

These are connected to the pins on the DIN connector. Different voltages are needed for different functions of the +3.

The ratings are VERY SIMILAR, but NOT IDENTIAL to the +2 PSU. The +3 needs more current, so the +3 power supply can be used on a Black +2. BUT NOT THE OTHER WAY AROUND. The Black +2 PSU should NOT be used on a +3.

This article will be updated with some photos of the internals, in the near future.

If you are looking to buy any Sinclair power supply or want one checked, please get in touch. I will happily sell you one – fully tested and working – for the Spectrum 16/48k/Plus, for the grey +2 or the black +2 or +3. I also have a lot of other Spectrum parts, working computers and games for sale. I will happily put together a custom bundle for you.

I will be writing more about the Spectrum power supplies in the near future. This series will conclude with the Amstrad-era models of the Spectrum, the Black +2 (Part 4) and the +3 (Part 5). When I finally get my Spectrum Next (that I’ve already paid for via the Kickstarter 2), I might even do an article on that, too! Watch this space!

Horace Goes Skiing Disassembly – READ_KEYBOARD routine at 28234.

hgskiing_fully_ldirs_run.skool: Routine at 28234
Prev: 28182 Up: Map Next: 28480
28234: READ_KEYBOARD Keyboard detection routine. Also does other things BEFORE looking at the keyboard. Uses documented QZIP keys. Also allows Interface 2 1234 and 6789 keys to be used instead (undocumented). And allows S key to pause, any bottom row key resumes (also undocumented). Also checks H and G keys – if both are pressed, restarts the game by setting 24249 Uses variable at 24248 and DEMO_OR_GAME_MODE variable at 24249 INPUT: no parameters OUTPUT: B = ONE and only ONE of 0 (UP), 1 (RIGHT), 2 (DOWN), 3 (LEFT) on RETurn Game variables changed: 24262 – these probably all relate to the location of Horace 24261 24260 24220 24249 DEMO_OR_GAME_MODE CALLS: 28077 Call DO_SOME_ATTRIBUTE_WORK Game variables read but not changed 24248 only BITs 210 used ?
28234 LD BC,1271 B = 4, C = 247 – C used for keyboard check later
28237 LD DE,24248 Check 24248
28240 LD A,(DE) A = (24248)
28241 AND A Test if any bits are set, result in A
28242 JR Z,28335 If 24248 is zero, A AND A is 0, then jump to 28335 (CHECK_PAUSE_ACTIVATE)
28244 BIT 0,A 24248 is not zero, at least one bit was set in 24248, so check BIT 0
28246 JR NZ,28256 If BIT 0 of 24248 is 1, jump to 28256
28248 CP 2 BIT 0 is zero, so check if BIT 1 is set (only BIT 1)
28250 JR Z,28297 If 24248 = 2 (10 binary), then jump to 28297
28252 LD B,0 If A (24248)!= 2 set B = 0
28254 JR 28299 Jump to 28299
28256 CP 5 BIT 0 of 24248 is 1 if we are here, is A = 5?
28258 JR Z,28285 If A (24248) = 5 BIN 00000101 then jump to 28285
28260 LD HL,24262 HL = 24262
28263 LD A,(HL) A = (HL)
28264 AND A A AND A
28265 JR NZ,28269 If A AND A is non-zero (any of the bits set), jump to 28269
28267 LD (HL),20 24262 is 0, so set 24262 = 20
28269 DEC (HL) (HL)–
28270 LD A,(24261) A = (24261)
28273 JR NZ,28279 If (24261) is non-zero, go to 28279
28275 XOR 3 A is 0, so 00 XOR 11 is 11 (3 decimal)
28277 OR 1 A = 3 (11 binary), so 11 OR 01 is 11
28279 LD B,A B = A = 3 (11)
28280 LD (24261),A Set 24261 = A = 3 or non-zero original value of 24261 from 28270
28283 JR 28299 Jump to 28299
28285 CALL 28077 A was 5 from 28258, so now DO_SOME_ATTRIBUTE_WORK
28288 AND 3 Only want bits 10 of A, discard the rest
28290 BIT 0,A Test only BIT 0
28292 JR Z,28318 Jump to READ_KEYBOARD if BIT 0 of A is ZERO
28294 LD B,A If BIT 0 of A is 1, set B = A
28295 JR 28299 Jump to 28299
28297 LD B,2 24248 = A = 2, jump here from 28250
28299 LD HL,24260 24248 != 2, B already set to 0
28302 DEC (HL) 24260–
28303 JR NZ,28318 If A != 0, jump to 28318
28305 LD (HL),90
28307 LD A,(DE) A = 24248 (again)
28308 INC A A = A + 1
28309 CP 5 Subtract 5 from A to compare
28311 LD (DE),A 24248 = A + 1
28312 JR C,28318 If A > 5 then jump to 28318
28314 XOR A A <= 5, so set A = 0
28315 LD (24220),A Set 24220 = 0
28318 XOR A READ_KEYBOARD A !=0 if came from 28303, so set A = 0
28319 IN A,(254)
28321 AND 31 Use only 5 rightmost bits
28323 CP 31 If all 5 43210 bits are 1 then no key pressed
28325 RET Z If no key pressed then return
28326 XOR A A = 0
28327 LD (24220),A Set 24220 to be zero
28330 INC A A = 1
28331 LD (24249),A Set DEMO_OR_GAME_MODE to be 1 (GAME)
28334 RET And return (GAME must have started?)
28335 LD A,253 CHECK_PAUSE_ACTIVATE 24248 was zero, so jumped here
28337 IN A,(254) Read keyboard A – G half-row
28339 AND 2 Use only S key (BIT 1)
28341 JR NZ,28363 If S key is pressed, BIT 1 is zero, so AND 2 is non-zero, so go to 28363
28343 LD A,127 S_KEY_PRESSED Bottom right half-row B to SPACE
28345 IN A,(254)
28347 AND 31 Discard bits 765 as meaningless. Use only bits 43210
28349 CP 31 If all bits 43210 are 1 = 31, and no key pressed.
28351 JR NZ,28363 If zero, all bits 1. Otherwise at least one key was pressed, so jump to CHECK_H_KEY
28353 LD A,254 Bottom left half-row CAPS SHIFT to V
28355 IN A,(254)
28357 AND 31 Discard bits 765 as meaningless
28359 CP 31 If all bits 43210 are 1, no key pressed
28361 JR Z,28343 LOOP_PAUSE If no key pressed, jump back to S_KEY_PRESSED – 28343 – no bottom row key pressed
28363 LD A,191 CHECK_H_KEY This is H to ENTER half-row
28365 IN A,(254)
28367 AND 16 Check only bit 4 which is H key
28369 JR NZ,28383 If H is pressed, bit 4 is ZERO, AND 16 is ZERO – jump to CHECK_MOVEMENT_KEYS
28371 LD A,253 CHECK_G_KEY H key has been pressed
28373 IN A,(254) Read keyboard A – G half-row
28375 AND 16 Check only bit 4 which is G key
28377 JR NZ,28383 If G is pressed, bit 4 is ZERO, AND 16 is ZERO – jump to CHECK_MOVEMENT_KEYS
28379 INC A A is zero if 28377 did not jump, so set A = 1
28380 LD (24249),A DEMO_OR_GAME_MODE set to GAME Mode = 1 which starts a new game
28383 LD DE,57327 CHECK_MOVEMENT_KEYS D = 223, E = 239
28386 LD A,D CHECK_RIGHT_KEYS Y to P half-row of keyboard
28387 IN A,(254)
28389 BIT 0,A Check P key
28391 JR Z,28407 If BIT 0 is ZERO, P was pressed, then jump to 28407
28393 LD A,E Top right half-row 6 to 0
28394 IN A,(254)
28396 BIT 3,A Check 7 key
28398 JR Z,28407 If BIT 3 is ZERO, 7 was pressed, then jump to 28407
28400 LD A,C C = 247
28401 IN A,(254) Read from top right half-row 1 to 5 keys
28403 BIT 1,A Check 2 key (BIT 1)
28405 JR NZ,28409 If 2 key was pressed, BIT 1 is ZERO, jump to 28409
28407 LD B,1 GO_RIGHT_KEY_PRESSED One of the “Go right” keys was pressed (P,7,2) – set B = 1
28409 LD A,C CHECK_LEFT_KEYS C = 247 from first LD BC at 28234
28410 IN A,(254) Read from top right half-row 1 to 5 keys
28412 BIT 0,A BIT 0 is 1 key
28414 JR Z,28430 If 1 key is pressed, BIT 0 is 0, jump to GO_LEFT_KEY_PRESSED
28416 LD A,D D = 223 from 28383 which is executed in all cases
28417 IN A,(254) 223 represents Y to P keys
28419 BIT 2,A BIT 2 is the I key
28421 JR Z,28430 Bit 2 will be 0 if I key is pressed, so jump to GO_LEFT_KEY_PRESSED
28423 LD A,E E = 239 from 28383
28424 IN A,(254) 239 represents 6 to 0 keys
28426 BIT 4,A BIT 4 is the innermost (leftmost) key, which is 6 key
28428 JR NZ,28432 If it is pressed, it will be zero, so do not jump and enter GO_LEFT_KEY_PRESSED
28430 LD B,3 GO_LEFT_KEY_PRESSED – set B = 3
28432 LD A,E CHECK_UP_KEYS E = 239 from 28383
28433 IN A,(254) Checking 6 to 0 half row of keys
28435 BIT 1,A BIT 1 is 9 key
28437 JR Z,28454 If 9 key is pressed, BIT 1 will be zero, so jump to UP_KEY_PRESSED
28439 LD A,251 Checking 1 to 5 half row of keys
28441 IN A,(254)
28443 BIT 0,A BIT 0 is outermost key which is Q
28445 JR Z,28454 If Q key is pressed, BIT 0 will be zero, so jump to UP_KEY_PRESSED
28447 LD A,C C = 247 from first LD BC at 28234
28448 IN A,(254) Checking 1 to 5 half row of keys
28450 BIT 3,A BIT 3 is 4 key
28452 JR NZ,28456 If it is pressed, it will be zero, so do not jump and execute next line
28456 LD A,C CHECK_DOWN_KEYS C = 247 from first LD BC at 28234
28457 IN A,(254) Checking 1 to 5 half row of keys
28459 BIT 2,A BIT 2 is 3 key
28461 JR Z,28477 If 3 key is pressed, BIT 2 will be zero, so jump to DOWN_KEY_PRESSED
28463 LD A,254 CAPS SHIFT to V half-row of keys
28465 IN A,(254)
28467 BIT 1,A Check BIT 1 which is Z key
28469 JR Z,28477 If Z is pressed, A will be 0, so jump to DOWN_KEY_PRESSED
28471 LD A,E E = 239 from 28383
28472 IN A,(254) Check 6 to 0 keys
28474 BIT 2,A BIT 2 is 8 key
28476 RET NZ If BIT is NOT zero, then return without signalling down key.
28479 RET B = ONE and only ONE of 0 (UP), 1 (RIGHT), 2 (DOWN), 3 (LEFT) on RETurn
Prev: 28182 Up: Map Next: 28480

Hungry Horace Goes Skiing? on the Sinclair ZX Spectrum

Is it Hungry Horace
or Horace Goes Skiing?
Photo Courtesy of Martin Russell

Horace is one of the most famous, iconic even, characters of games on the Sinclair ZX Spectrum. There were three official titles in the Horace series from Australian software house Melbourne House:

  1. Hungry Horace (1982)
  2. Horace Goes Skiing (1982)
  3. Horace and the Spiders (1983)

But what is the game in the photo at the top? Is it Hungry Horace? Is it Horace Goes Skiing? Or is it Hungry Horace Goes Skiing?

It is a misprint and is a rarer find in the world of collecting Spectrum games!

PopeyMon is currently working on a disassembly of Horace Goes Skiing. A disassembly is a reverse engineering of the machine code programming that makes up a Spectrum program.

It is being done using SkoolKit, the excellent software tools written in Python by Richard Dymond. Richard has done a disassembly of Hungry Horace, as well as other iconic Spectrum games like Skool Daze, back to Skool, Manic Miner (more articles are on PopeyMon about Manic Miner – see the tags) and Jet Set Willy.

Manic Miner

Richard has also made another great contribution to Spectrum programming by publishing an online version of The Complete Spectrum ROM Disassembly, originally published by Melbourne House of Horace fame.

UPDATE (29/4/21): Undocumented features and keyboard controls found! Possible “missing” 11th ZX Spectrum ROM Cartridge game? The READ_KEYBOARD routine has been disassembled. I have published it at this link here. There is some tidying up that is needed, and the non-keyboard sections need to be understood more clearly, but I wanted to report some interesting news for Horace fans! The inlay for Horace Goes Skiing only reports four keys to play the game – QZIP for up/down/left/right.

BUT… In doing the disassembly, I discovered more keys. 1234 and 6789 can also be used to control Horace. In fact, all three key combinations QZIP/1234/6789 can be used simultaneously.

To me, this suggests that Horace Goes Skiing was considered for a release on the ZX Spectrum ROM cartridge format. It is by no means definitive proof – just a theory. But there are other reasons – please see below. I have discussed it with the author of the definitive website on ZX Spectrum ROM cartridges here – Paul Farrow. I have also published it to a couple of the Spectrum forums, and it has generated some interest. More on that another time.

Undocumented Keys for Horace Goes Skiing

I have tested my disassembly findings by loading Horace Goes Skiing from tape onto a proper Spectrum instead of an emulator. I attached my Kempston Joystick Interface with ROM cartridge – this is very similar to the ZX Interface 2. I have confirmed my findings on the undocumented keys:

  1. I have confirmed that all three key combinations and/or the Interface 2 joystick ports can be used simultaneously.
  2. The S key can be pressed to PAUSE Horace Goes Skiing. Keys on the bottom left half-row can be used to resume.
  3. The ENTER key can be used to “toggle” (turn off and turn on) the Ambulance sound. This seems to have an effect on the running of the game too, but whether it can be used as a CHEAT to slow the Ambulance down is unknown so far.
  4. Pressing the G and H keys simultaneously ABORTS THE GAME.

In addition to this, there are also the following reasons to support my theory that Horace Goes Skiing was going to be the 11th ROM cartridge game, but was abandoned:

Horace Goes Skiing Is A Possible 11th ZX Rom Cartridge

I believe that Horace Goes Skiing may have been a candidate for ROM cartridges, as:

  1. Skiing is the “sequel” to Hungry Horace.
  2. Horace and the Spiders and Hungry Horace were released on ROM cartridge, but Skiing was not.
  3. Skiing is a 16k game, which was required for the ROM cartridges.
  4. Skiing was released at about the right time, on the Sinclair label.

Paul Farrow has come back with his views as to why Skiing may or may not have been intended for a ROM cartridge. We have continued the conversation, but he says that:

“Iā€™m not so sure it does suggest that, but neither do I rule out the theory off hand. I think more evidence would be required to draw that as a definite conclusion.”

I will keep following up on my theory and diassembling the rest of the game. But for now… that is all!

UPDATE (23/4/21): The .skool files have been updated to document a lot more of the disassembly. The purpose of around 50% of the routines has been determined and many routines have now been fully understood and documented.

At the time of writing, my disassembly of Horace Goes Skiing has made substantial progress:

  • The initial trickery of game loading and movement of data and code, after the game has loaded, has been hurdled.
  • The main game loop has been found and some of the sub-routines have been documented such as the squelchy sound of the attract mode and the colour attribute animations.
  • The main text strings for the game messages have been found.
  • And the SkoolKit tool has been mastered to enable publishing of the disassembly on the PopeyMon Games and Fun website.

So keep ’em peeled for the disassembly, if you want to learn more about Horace and his games.

You might even learn some machine code and how to use SkoolKit!

What Kind of Spectrum Would You Like?

An Original 48k Sinclair ZX Spectrum
Refurbished For A Happy Customer

Above is a photo of an original 48k Sinclair ZX Spectrum with the rubber keys, which has been refurbished to a very high standard by PopeyMon Games and Fun.

It was sold in a package which was put together by PopeyMon following a request by a customer for a custom bundle, so that he could get the joy back from having a Spectrum just like the one he had almost 40 years ago. The Spectrum was released in 1982.

It is the customer’s own photo, which he has given permission for me to use. PopeyMon has been given the following endorsement by the customer, Mr. L. Stevenson of Essex:

“I received my Speccy bundle today all packaged and looking amazing… everything is in great working order as promised and I can now enjoy playing my spectrum 48k once again after 40 years! Extremely happy with the service and delivery of such a special machine. Thank you”

PopeyMon has put together many Spectrums, and custom bundles, and many types of Spectrum, for a lot of happy customers over the past two years.

So what kind of Spectrum would you like?

Do you want it to be like the original Spectrum above, or another model as shown below? PopeyMon has expertise in all models of Sinclair ZX Spectrum, in repairing them and refurbishing them.

Would you like it to be refurbished?

If you do want it to be refurbished, you can choose any of the following options, and I will give you a good price on the work and an agreed timescale for delivery. I also package things up properly, as shown in the endorsement above.

The above Spectrum + (Plus) has been opened up, as shown in the last photo. The machines are nearly forty years old now, so it is unsurprising that most will need some work.

This Spectrum + has been refurbished to a very high standard, with the following work done by PopeyMon:

  1. all electrolytic capacitors have been replaced with high quality Vishay capacitors. This is not absolutely necessary, because a Spectrum can operate successfully with the old ones, but they can deteriorate over time with heat, age, usage and under bad storage conditions. They can then damage other components, such as the RAM chips that are more difficult to replace,
  2. a better ULA chip, the 6C0001E-7 model which was the last one for the original rubber key models and Spectrum Plus,
  3. a new modern voltage regulator which means the Spectrum runs cooler and the heatsink can be removed,
  4. a new keyboard membrane, not shown in the photo above. These are manufactured new. The old ones usually dry out and stop working, and the ribbons that attach them to the computer’s board inside, become brittle and break. It is fitted for the customer,
  5. the TV display has been modified to be a composite video output, instead of the traditional
  6. the case and keys have been thoroughly cleaned, including every single key
  7. the edge connector has been tested with a joystick interface and with a modern SD-card solution such as DivMMC, Interface 1.bis or Retroleum Smart Card
  8. very thorough testing

Would you like a repair done? Send me some details of your machine to get the conversation going, with as much detail as you can of the symptoms and photos if possible. I can also do a part-exchange.

Would you like a tape player to load and save games?

Would you like a joystick and joystick interface to play games without using the keyboard?

What games would you like to play? I have a large stock and can get games in for you on commission.

Would you like your power supply checked and refurbished? These are old now. Do you really know that it is safe to use? I am PAT trained and have a lot of experience with these power supplies. I have a comprehensive guide to all Spectrum power supplies on this website. Be VERY careful what you might buy on eBay or cheap from China, without checking. What might seem OK could kill your Spectrum! Do get in touch.

PopeyMon offers all of the above services and products, plus more. I also buy Spectrums and anything Spectrum-related. I offer other products and services too.

Get in touch with PopeyMon – Contact Details at the link – for all your Spectrum needs!