Monday, 12 January 2009

Sinclair Spectrum 48k

This was the first computer that I got, in 1984, the current keyboard is newer , as it was purchased as a normal sinclair and late converter to the "plus" one (the only difference was the keyboard).

The machine has a zilog z80 microprocessor and has 16kb of ROM and a RAM memory of 48Ks, including 6912 bytes for the graphics display and other system variables so only about 40,5 kb where employed normally for games and software.

The programs where loaded from a tape (I still have too much tapes full of programs ;-), and it was possible to program in BASIC and machine code, the graphic resolution was not great , but some of the programs are still amazing .

In order to save RAM space the BASIC interpreter assingned one of the ASCII code to each of the language keyworks, so for example the "print" command employs only a a byte of memory. A complicated combinations of keystrokes allow to produce all the symbols, one of the various emulator was named "JPP" , due to the fact the "J" key directly puts the "load" command and the double quotes wre in the "P" key so JPP was roughtly load "" , the order to load any program form the tape.

In this picture you can see the power plug for the external power adaptor , the expansion slot and the tape plugs for connecting the machine to and external tape. Later sinclair models (+2) have the
tape incorporated to the machine.

I'll try to find all the hardware (for example a game save device, parallel port, etc) that I 'd for this machines

The most usual problem with this macine was the keyboard, under the plastic cover in the Spectrum 16k and 48k, there were this plastic membrane that was easily broken when you tried to play games, and the only solution was to replace it.

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