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The TS2068, the TC2068 and the TC2048 each share the same basic internal design, described immediately below:
* The TC2068 is the Portuguese made European version operating at 50Hz on a 230-240v power supply and generates a PAL television signal (used throughout Europe, except in France where SECAM is used instead) with a normal expansion bus. Both machines feature an AY-3-8912 sound chip (not 128 compatible), an extended version of BASIC in 24K of ROM (semi-compatible), two non-standard joystick ports, a cartridge dock (not IF2 compatible), and a new ULA with extra video modes, but some incompatiblities. There is also a Polish clone of the TC2068, called the UK2086, which substitutes an RS232 port for one of the joystick ports.
* The TC2048 was designed and produced in Portugal. Basically, the TC2048 is a TC2068 with all the extra hardware removed, except the new ULA, but a normal BASIC ROM (only slightly modified), a BNC composite out (but no RGB signals on the bus), and a Kempston joystick port (but no +5v as needed by autofire joysticks).* The TS2068 is an American machine operating at 60Hz on a 110v power supply and generates an NTSC television picture (just like the Spectrums sold by mail order in the US by Sinclair) but with a TS1000 (ZX81) compatible expansion bus.
There are also two modified versions of the TC2048; the TC2128 (Rebuiltion or similar) and the TC2144 (by Jarek Adamski). The TC2128 extends the TC2048 to 128K using the Spectrum 128 memory scheme. The TC2144 does the same but provides an extra 16K of memory between 0x8000 and 0xc000. Both upgrades allow the ULA to use the shadow screen in Bank 7 giving the machine a total of four screen areas.