ZX Spectrum Guide

The ZX Spectrum are a series of 8-bit computers first released in the UK in 1982. They were sold first by Sinclair Research and later by Amstrad. Similar to the C64 in America, the ZX Spectrum was one of the first computers aimed at the general public and it kickstarted interest in computers and the software industry. It sold around 5 million units, not counting unofficial clones.

Hardware-wise, the ZX Spectrum is build around a Zilog Z80 at 3.5 Mhz and came with either 16 Kb. or 48 Kb. of RAM. Models Spectrum 128 and + 2/3 had 128 Kb. RAM.

The Spectrum could display color graphics at a resolution of 256×192, using 7 colors with two brightness levels and black. The Spectrum color graphics had important limitations, which resulted in a very recognisable aesthetic.



Many games have monochrome graphics, with some color touches reserved to the scoreboard.

Original Spectrums had little to offer in the sound department, but starting with the Spectrum 128 they included the General Instrument AY-3-8910 sound chip, featuring a 3-voices Programmable Sound Generator.

Variations.

Sinclair Research produced three versions of the Spectrum: the Spectrum 16/48k, the Spectrum+ and the Spectrum 128. The later is the most advanced model, with 128 Kb. RAM and the General Instrument AY-3-8910 sound chip.

These Sinclair Research models have flat, black cases with rubber keys.

Amstrad bought the Spectrum rights in 1986 and released different models they labeled as + 2 and + 3. These models use taller cases with a full-stroke keyboard and an embedded cassette player (+ 2) or disk unit (+ 3). Amstrad likely reused the cases of their CPC computers for these. They all come with the enhancements of the Spectrum 128, with extra RAM and sound capabilities.



Around 1982 Sinclair started cooperating with Timex, in order to introduce the Spectrum into the American market. Several Timex Sinclair computers exist, and they are the only licensed Spectrum clones.



Of these computers, the 2068 and 2048 models are the closest to the ZX Spectrum, but they are not entirely compatible because of hardware changes.

A further variation of the Spectrum would be the unlicensed eastern Europe clones. These were a series of computers built in different countries of the Communist block during the 1980s and 1990s, like the Didaktic in Czechoslovakia and the Scorpion and Pentagon in Russia. The Scorpion in particular is interesting because of its numerous enhancements: Up to 2 Mb. RAM, IDE controllers and TR-DOS, CP/M and IS-DOS operating systems.


How to load games.

We load Spectrum games from either tape or disk images. Disk images are only supported by the + 3 model.

1) Tapes.

In 48k models, we enter the LOAD"" command from the BASIC prompt.



The usual shortcut is J followed by MAYS+P, twice.

In 128k models we have the luxury of a start menu:



So we press ENTER and the tape will start loading.

In both cases, we may need to press PLAY to start the tape.

2) Disks.

As I said, disks are only supported by + 3 models. We use the first option in the start menu to load them.



Most games will run better un a Spectrum 128 model.

Then there's the subject of joysticks. Except the Amstrad models, Spectrums plugged joysticks through a series of external interfaces, such as a Sinclair or Kemspton interface. My advice is to map the joystick to the keyboard and emulate a Kempston interface. However, some games won't support this configuration, so be prepared for alternatives.


Recommended emulators.

Want a solid, simple and reliable ZX Spectrum emulator? Then my first option would be Klive by Steve Snake.



A more complex -and satisfying option- would be Retro Virtual Machine. It has a very funny interface where you need to drag and drop files into a virtual computer, and video emulation so good you'll think you're using the actual machine.



Both Klive and Retro Virtual Machine emulate official Spectrum models only. If you want to emulate unlicensed clones like the Pentagon or the Scorpion you need to check out more advanced emulators, such as Speccy or Spectaculator.

 

Now let's see what the machine can do... MobyGames lists nearly 3.500 ZX Spectrum games available, but here are two of my favorites...

Isometric adventures were very popular in the Spectrum. You may remember titles like Alien 8, Knight Lore, Head over heels or Batman (the second game, not the movie adaptation). This one is called The Final Matrix and I find it criminally underrated. In it you play a little robot, whose mission is to rescue several of his companions from a chain of prisons known as the Matrix.

Every jail consists of a series of isometric cells, filled with enemies, traps and simple puzzles. Your robot can use and fire weapons, but I think you're supposed to avoid confrontation whenever possible, because those aliens are tough and ammo is scarce. Once you locate the prisoner, you need to return to the beginning of the level and teleport to your ship. Yep, with the prisoner in tow. This is not an easy game.

But it has plenty of cells, enemies and puzzles. And you can also play ANY level you want, in any order. Cool, huh?

My second recommendation is a far more popular game, RoboCop. British developers Ocean were known at the time for their movie licenses, and this is one of their better ones. It's loosely based on the arcade by Data East, but with a few unique twists, like 3D shooting levels and a puzzle where you need to recreate the face of a suspect. Top notch stuff, and action packed too.

 

Since I already mentioned the Spectrum clones... here's the SAM Coupé.


This computer was released in 1987 by Miles Gordon Technology, and it was designed by former Sinclair employees. It was both a Spectrum 48k clone and an attempt to update the Spectrum hardware. For instance, it supports the same graphic modes of the Spectrum, but now they can display 16 colors simultaneusly. It had a Z80B CPU at 6 MHz, 256 Kb. RAM, and a Philips SAA1099 sound chip. Software was loaded through an integrated disk drive with 800 Kb. of capacity.

The SAM Coupé used SAM BASIC as an OS, but it was also compatible with CP/M v2.2.



Unfortunately for MGT, the SAM Coupé sold very poorly, around 12.000 units in total. It was buggy, its compatibility with Spectrum 48k software was overvalued and computer users preferred to buy the new 16-bit computers instead.

Most software for the SAM Coupé was created after the demise of the system and runs from disk, either directly booting from disk or entering the BOOT command from BASIC.

Its best known game is probably its version of Prince of Persia:

 

I just got sunburned after visiting a local swimming pool. If happens when you underestimate the sun and you're too stingy with the protective cream. So, where was I? Oh, yeah, the Spectrum.

You may think the ZX Spectrum appeared out of nowhere in 1982. I don't blame you. Hell, most of you were probably born after that year (shudders) and have only heard of these machines through older relatives, the retro-scene or who knows why. Anyway, no, the ZX Spectrum wasn't the first computer by Sinclair Research. It was the Sinclair ZX80, in 1980, back when Sinclair Research was still called Science of Cambridge Ltd. And it was also a predecessor to the ZX Spectrum, which makes these two machines related.



Before it was released, British computer enthusiasts had to rely on American imports such as the Apple II or the Tandy TRS-80. The ZX80 was also the first computer to be released in the UK for less than 100 pounds. It could even be bought in the shape of a kit for around 80 pounds. It was so succesful that soon there was a waiting list in order to obtain it.

But don't be fooled by its futuristic looks. Compared with the next Spectrum models its capabilities were rather insignificant. And compared to today's computers? The comparison would be very cruel. The ZX80 was so basic that if you pressed any key the screen would blink. Because the computer couldn't receive data and update the screen at the same time!

These computers employed a Zilog Z80 CPU at 3.25 - 3.55 Mhz., had 1 Kb. RAM (which could be upgraded to 16 Kb.) and had no dedicated video or sound hardware. They could show text in 32x24 characters and extremely basic graphics at a 64x48 resolution. In black or white. Software was loaded and saved from / to an external cassette unit. Yet these specs weren't bad for the time, and the ZX80 was very successful.



The Sinclair ZX81 was released in 1981, and it improves on the ZX81 in several ways. It had a better keyboard and was more reliable than the ZX80. Its ROM was revised and now was twice the size of the original, going from 4 to 8 Kb. It even could work in "slow mode" while the keyboard was pressed.

Both systems had numerous clones, but official and unlicensed. The ZX80 can also be found as the MicroAce, as the TK80 or as the NE Z80. The ZX81 was cloned officially as the Timex Sinclair 1000 and 1500, and unofficially as the Microdigital or Prologica (in Brazil) or Czerweny (in Argentina).

Apart from MAME, I've only tried two emulators for these systems. The first one is EightyOne by Michael D. Wynne, and the other one ZesarUX by César Hernández Bano. Both emulators also offer ZX Spectrum emulation among others.

If you use any of these two emulators you won't need to type anything to load games. In any other cases, you load programs with the LOAD"" command.

So... are there any games for this systems? Yes, naturally. But you need to consider how basic these machines were. Things like scroll were beyond their capabilities. So we're talking about stuff like text adventures or action games with graphics reduced to their minimal expression.


Adventure D: Espionage Island


Star Trek (19xx)(Gemini Marketing)

You may also stumble into versions of classics like Breakout, Kong or Space Invaders.

 

Today, just a quick note on one of the most common issues with ZX Spectrum graphics. Yes, I'm talking about color / attribute crash.

Because the ZX Spectrum was one of the first popular home computers, it was also designed to be cheap and affordable. It didn't have graphic chips as we know them today. I don't even think they had a CTRC (Cathode Ray Tube Controller) like the Amstrad CPC did.

Despite this, the ZX Spectrum could display graphics at a 256×192 resolution with 15 colors. In order to create these graphics, the Spectrum divided the screen are into 8x8 "regions". Inside a "region", only two different colors could be used. This created the color crash problem: In a moving screen, if a single pixel inside a "region" entered another "region", the first one changed colors.


Color clash in "Treasure Island Dizzy"

Of course, there were a few solutions to prevent color clash:

1) To ignore it. This was the usual behaviour in the first years of the platform.

2) Monochrome display. As we say in Spain, if you kill the dog you get rid of rabies. So, no color, no color clash. Clever, isn't it? That's why so many ZX Spectrum games are in monochrome.


"After the War" keeps the main game area in monochrome to prevent color clash

3) Limiting sprite movement. Okay, so the problem comes from a sprite entering another "region", right? So what if that's not possible? Problem solved!

4) Transparent sprites! Essentially, you get sprites in two colors, usually black and whatever color is used in the background. And when the color in the background changes, so does one of the sprite colors.


"Chase H.Q.": notice how sprites change color on the upper half of the screen

5) The most creative solution: creating a border around the offending sprites. Then the colors don't collide and the problem is solved. Of course, this requires a lot more work.


"Golden Axe" draws a black border around sprites