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Sothius' Home-Museum- Sinclair-Sinclair ZX Spectrum 48K-additional pictures

Sinclair ZX Spectrum logo (10 KBytes)

Sinclair ZX Spectrum 48K


Sinclair ZX Spectrum 48K (78 KBytes)
The tiny ZX Spectrum with its 'rainbow stripes'. Behind you can see part of a ZX81 (for size comparison)
(picture copyright by M.A.Grundke)



Specifications

NameSinclair ZX Spectrum 48K
CodenameZX82 (being the popular ZX81's successor)
Made bySinclair Research Ltd., Cambridge
Released
  • 1984 (this ISSUE 6A machine)
  • the first ZX Spectrum appeared in April 1982
Serial-No.005-511618
Additional infosinclair
ZX SPECTRUM PERSONAL COMPUTER
PATENT PENDING
MADE IN UK
Board-info
CPUZilog Z80A (8080-descendant)
Speed3.54690 MHz
RAMPCF1306P ULA (address decoding/ multiplexing)
  • 48 KBytes:
  • RAM bank 2 is, in most Spectrums, fitted with 64Kx1 DRAMs, although they can only be addressed as 32Kx1 anyway. Reason is that Sinclair bought RAMs of a certain defective charge (the second half of their capacity unaccessible), to reduce the cost
  • the Spectrum 16K was the same but came with only bank 1 fitted
ROM/ Native OSSinclair ZX Spectrum BASIC 16K
  • contains the operating system and BASIC interpreter
  • extended capabilities compared to its ancestors' 8K BASIC, such as an ASCII character set or support for the machine's advanced features
Keyboard/ LayoutRubber keyboard
  • 40 keys/ US (QWERTY)
  • 183 functions, plus 8 for color selection, auto-repeat
  • The later Spectrum+ (1984) had a standard-keyboard similar to that of the Sinclair QL
GraphicsFerranti 6C001E-7 main ULA (TV-output)
  • Max.Res.: 256x192 pixels
  • Text: 32x24 characters with graphical charset
  • Max. Colors: 8 (but only 2 usable per 8x8 pixel-square)
  • this machine's a PAL-version
  • in both Sinclair ZX80 & ZX81, the CPU alone generated the TV-output. Using a dedicated IC here was a great leap forward
Soundcreated by ULA
  • integrated 40 ohm loudspeaker
  • 10 octaves (130 semitones) via BEEP-command (BASIC)
  • can be connected to an external amplifier (via jack-sockets)
Media
  • standard Audio-cassettes (via standard cassette-recorder, 1500 baud)
  • later: Sinclair ZX Microdrive, which stored up to 85 KBytes on a small tape cartridge, transfer speed was about 15 KBytes/s. The microdrive could only be used in connection with the Interface 1, and although being a cheap and fast solution these days, its cartridges were known to be little reliable
Input/ Outputthe 6C001E-7 ULA is also used here (e.g. port I/O)
  • 54 pin male edge conn. expansion slot
  • RF TV-out
  • 3.5mm jack socket headphones-out ('EAR')
  • 3.5mm jack socket microphone-in ('MIC')
  • 9V DC-in
Miscellaneous
  • The ZX Spectrum was the direct successor to the ZX81 (thus also called ZX82) and Sinclair's first bigger success in the computer markets
  • Like its above-mentioned ancestor, it was a low-cost machine. It also used standard audio-cassettes as media and had a cheap rubber keyboard. And just like the ZX81's, the machine's keyboard also provided up to 5 functions per key - some keys even have six!
  • There were two versions:
    • the Spectrum 16K had (as the name implies) only 16 KBytes, but could be expanded to 48 KBytes easily (via empty RAM sockets)
    • the Spectrum 48K was the same, except for it came pre-equipped with 48 KBytes RAM
  • In 1984, Sinclair introduced the Spectrum+ with a QL-like keyboard, because a major complaint about the earlier Spectrum was its bad keyboard. However, a Spectrum+ upgrade kit was available for the old machines (which was more or less a Spectrum+ case and keyboard)
  • Later followed the Spectrum 128K (in 1985) and, after AMSTRAD had bought the rights on Sinclair-computers, the Spectrum +2 and Spectrum +3. All three had a better BASIC and a new three-channel soundchip, similar to that of the ATARI ST. Spectrum +2 and +3 also had an internal cassette-recorder, similar to AMSTRAD's CPC464


'Enduro Racer 128' screenshot  (16 KBytes) 'Salamander' screenshot (21 KBytes)
Because the Spectrum was a very popular game-machine (especially in the U.K.), many arcade-games were ported to it, like Sega's 'Enduro Racer' (left) or Konami's 'Salamander'

All trademarks mentioned on these pages belong to their respective owners (if they still exist). All other content, including pictures is (C) M.A.Grundke (aka Sothius), unless otherwise noted. Unauthorized copying or usage of that content, without former permission from M.A.Grundke or the rightful copyright-holder, is prohibited

Sothius' Home-Museum- Sinclair-Sinclair ZX Spectrum 48K-additional pictures