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       #Post#: 174--------------------------------------------------
       Timex TS 1000, Microdigital TK83 and Czerweny CZ 1000
       By: IngDuenas Date: November 16, 2016, 9:03 pm
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       The Timex TS 1000 and its clones (yeah, clone of a clone,
       wondering if its electronics DNA was faithfully copied) were
       basically a ZX81, the only noticeable difference was the amount
       of RAM, 2Kb (TS1000 and CZ1000) instead of 1Kb!. Both the Timex
       and the Czerweny have the same ULA the ZX81 carried, same power
       supply but the modulator was "tuned" for NTSC instead of PAL so
       the Xtal was also for NTSC standard (about 3.57Mhz instead of
       3.58Mhz of PAL systems). While Timex sold the official ZX81
       clone, renamed TS1000, Microdigital of Brasil and Czerweny of
       Argentina (mostly an induction motors manufacturer) produced the
       TK83 and the CZ1000, respectively. If I recall correctly, the
       TK83 did not have ULA but discrete logic as the ZX80 had.
       The extra Kb was welcomed but did not make a big difference
       unless you could program in Z80 assembly language where 1Kb was
       a lot of more memory to do things. All those companies produced
       16Kb RAM packs which also have the same issues the Sinclair RAM
       expansions had, hours of programming could be lost in a blink if
       the darn thing moved... So the usual solution, for the folks
       handy with a soldering iron, was to remove the board from the
       expansion and solder it straight to the main board.
       I did not own a CZ1000 but a TS1000, at the time I bought it I
       was a young guy starting to learn electronics at a technical
       high school in Argentina. After going through the user manual
       and learning BASIC and I could not fail to notice the weird
       writing at the right side of the character codes in the Appendix
       A of the manual. HEX? Z80 Assembler? After CBh? I actually had
       to go to the Engineering Faculty of the University in the city I
       live to find out! There, a physics proffesor, an Electrical
       Engineer, explained the meaning of all that to me and pointed me
       to the right literature...
       ... 30+ years later I am still proffiting from what the TS1000
       taught me. Countless nights spent (or is it invested?) trying
       machine code routines. I even managed to fit a Pac-Man like game
       in the available Kb! Awesome. Years later, I was able to apply
       the memory saving techniques and smart programming when writing
       firmware for the very limited Microchip PIC microcontrollers...
       Many thanks to Sir Clive! :)
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