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TIMEX Sinclair 1000
Additional pictures. Note that loading the page could take a while...
(pictures copyright by M.A.Grundke)

FCC ID: CEC8E4TS1000R1 Timex Computer Corporation Made in Portugal

TS1000 board overview: well, it's just a ZX81-board with some modifications. Beginning from the lower right, you can see the usual foil connectors for the keyboard. Above them, the major difference to the ZX81: a 6116 CMOS RAM (IC4) , prodiving the machine with double the amount of memory. Still above, the (ZX81-compatible) expansion port. Left from the RAM, the TS1000's BASIC ROM (IC2), a D2364C labeled SINCLAIR RESEARCH, the CPU (IC3) and the SCL (IC1). Still left, the RF-modulator, with DC in-, MIC- and EAR-connectors below. At the board's lower left is the voltage regulator with its heatspreader (you can see only a part of it). Now there are still two major differences to the ZX81: there's a CHANNEL 2/3 switch soldered to the TS1000's lower boardside, and (what's more important) the TS1000's case is completely covered by an aluminium (?) layer from the inside (shielding!)

board silkscreening, part 1 (board's lower side): sinclair 1981 © ISS 3 PCIB

board silkscreening, part 2: 1981 © ISS 3 SINCLAIR ZX81 Yep, it's just a ZX81...

board silkscreening, part 3: sinclair Left and above, the two keyboard connectors (without the foil cables, which were by far the most sensitive part of the machine)

The D780C is a NEC-manufactured Z80A-CPU. Like all Z80-CPUs, it is (to a certain extent) compatible with its ancestor, the Intel 8080. In the Sinclair ZX micros, however, the CPU was also used for outputting the TV signal - a dedicated GPU was unnecessary, reducing the production cost. On the other hand, with graphics enabled, it would consume about 75% CPU power, meaning the machine runs like a (hypothetical) 900 KHz Z80 (the so-called 'SLOW mode). An additional 'FAST mode' was implemented, in which graphics output was disabled for the sake of making full CPU speed available to programs

The Ferranti 2C210E 'ULA' ('Uncommitted Logic Array'). This custom-chip reduced the production-cost of the ZX81 (and thus the TS1000) in comparison to the ZX80 by integrating its entire TTL on one chip

The 2Kx8 CMOS RAM (6116-type, looks like a NEC) is responsible for the machines incredible amount of memory: 2 KBytes! It was enough for some BASIC programming and simple games, and double the amount of RAM compared to the ZX81. Like there, a RAM expansion at the expansion connector entirely disables the internal RAM. Also true for the TS1000 is the RAM limit, 56 KBytes. Although there were expansions with up to 64 KBytes RAM, 8K were covered by the BASIC ROM and thus unusable. But you won't complain if you only had 2 KBytes before!

That's the TS1000's Sinclair BASIC ROM, 8 KBytes in size and of course identical to that used in the ZX81. In later machines like the TS2048 and TS2068, however, TIMEX modified the ROM for compatibility (but I don't know exact details about that - do you?). As already mentioned, the ROM occupies 8K of the machine's memory map, and there's no way of changing that (unlike in other Z80-designs, such as AMSTRAD's CPC-series)

The machine's CHANNEL 2/3 switch, which can be operated from the machine's bottom. This is a difference to my ZX81, which doesn't have one (depended on the country the machine was produced for)

The TS1000's expansion port. Of course, there were also TIMEX memory-expansions for the machine. Because of the ZX81 board's properties, the internal 2KB were disabled when memory was present at the expansion bus

Also see the Sinclair ZX81, from which the TS1000 was 'cloned'!

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