ZX Spectrum

• Microprocessor: Zilog Z80.
• ROM: 16 KBytes organized from address 0000h, which contained a BASIC interpreter and some usefull features, e.g. the computer's typeset, which could be customized.
• RAM: 48 KBytes, counting the video memory.
• Video: 256 x 192 pixels screen eating up 6 KBytes of RAM, plus a color map of 768 bytes.It was fashioned in away that each group of 8x8 pixels (a character cell) could have a foreground and a background color and the attributes of Bright (lighter colors) and Flash (quickly exchanging the foreground and background colors).
• Sound: It had a built in speaker, that had to be activated "by hand" by the microprocessor, much like nowadays (as of 2001) winmodems. I.E., if you wanted a 440Hz beep, you had to activate the sound I/O port 440 times in a second. The ROM provided a routine to which you could specify frequency and duration of a beep.
• IO: It featured:
  • modulated PAL video out, ready to TV
  • input and output jacks for connection with a tape recorder, its default storage device
  • a Sinclair Interface 2 joystick port, which I soon realized was compatible with the ATARI 2600 joystick.
  • An expansion slot, to which one could connect all sort of stuff, including the multiface one. Well, the multiface deserves a node of itself.I didn't had one - it was more or less like today's game shark's, just more powerfull.
• BASIC interpreter: This mostly peculiar BASIC would not let you type any commands on a letter by letter basis. The text cursor had different modes that changed more or less automatically according to the context in a command or program line. Depending on the mode,a BASIC keyword would them appear as a whole, and the cursor would change to the text mode (L). Thanks to this feature, each keyword would take just one byte of memory, which was very important. It was changed in later models (spectrum + and spectrum 128). And when you had a program typed in, it could be edited in a menu like form.

There was a clone of it, the TK90X in Brazil, but no clones of the subsequent models. Today, one can see and play Spectrum games on several emulators that can be found for free on the Internet. The emulators will not do for the rubber keyboard, tough. *grim*

Spectrum variants:

• 1982 - ZX Spectrum 16k
• 1982 - ZX Spectrum 48k
• 1984 - ZX Spectrum + - 48k RAM, essentially a 48k with a new case.
• 1985 - ZX Spectrum 128 - Spectrum + Case with the addition of a huge heatsink on the edge, 128K RAM, 128K Basic introduced, AY-8192 sound chip gives three-channel sound for the first time, and through the TV too!
• 1986 - ZX Spectrum +2 - Case similar to Amstrad CPC464, Built-in tape drive, 128K RAM
• 1987 - ZX Spectrum +2A - As +2, but with a new motherboard, black case and +3 ROM
• 1987 - ZX Spectrum +2B - As +2A, but made in Taiwan, not Hong Kong
• 1987 - ZX Spectrum +3 - Case similar to Amstrad CPC6128, Built-in 3 inch disk drive, 128K RAM

Spectrum-related products:

• ZX80 - 1k RAM, Membrane Keyboard
• ZX81 - 1k RAM, Membrane Keyboard
• QL - 16-bit 68000 based machine
• DKTronics Keyboard - A keyboard with 'proper keys' which took the innards of a ZX Spectrum for all rubber key haters.
• Sam Coupe - A bit of an oddity, with 3.5 inch disks, up to 2mb RAM (512k internal), and better graphics and sound.

The 16K-RAM and original 48K-RAM "Speccy" models' keyboard was lovingly described as "dead flesh" due to its feel. DKTronics made replacement keyboards with proper keys, and later 48K Spectrums (the "Spectrum + 48K") were released with rounded-key keyboards (as seen on the QL, I believe).

Early 128K Spectrums were released by Sinclair Research, and featured sound chips (like the Amiga's), VDU and keypad connectors, a ramdisk, "calculator" mode, "tape tester", test card screen, and 48K-mode for the more obstinate games. They had a Spectrum Plus-style keyboard, with all the 48K-mode keywords on, and an additional heatsink down the side. The BASIC interpreter was still keyword-driven, with a couple of new additional commands (PLAY, to drive the sound chip, being one of them), but the new full-screen editor did the tokenisation for you.

However, the Sinclair Research bubble was soon to burst, and Alan Sugar (of Amstrad fame) took over production of the 128K spectrum, as it shared the same Z80 CPU as his CPC range of computers. For cheapness' sake, the "Spectrum 128+2", "Spectrum 128+3" and "Spectrum 128+2A" also shared the same keyboards with integrated tape drives (which were notoriously unreliable) and disk drives (which were the doomed 3in-wide variety). (Re-)design issues meant the pinouts on the expansion ports differed in subtly incompatible manners between models, and the new cases meant some peripherals were no longer connectable anyway.