Review: The Timex Sinclair 1000

Timex Corporation has joined the ranks of manufacturers offering personal computer by making a close relative of the Sinclair ZX81 under agreement with Sinclair Research.

Like the ZX81 (IA Oct 82), the TS1000 uses a Zilog Z80A or equivalent processor with clock speed of 3.25MHz. It has the same smallpressure sensitive membrane keyboard. Those who are used to regular keyboards will find it annoying, but novices will find it easy enough to use. The TS1000 has an ” enter” key instead of the ZX81’s “newline.”

We found no differences between the Basic interpreters on the two machines. The display-black-on-white-is generated by the internal RF generator. As with the ZX81, this tends to roll and pitch a little-a problem all Sinclair users seem to complain about.

The TS1000 comes with a 2K built-in memory, twice the size of that in the ZX81. Clearly, the manufacturers have realized that 1K was just too
small for any worthwhile programs. The 2K workspace allows serious calculations to be performed. All this is not a bad value at the $99.95 listed price. The memory expansion to 16K lists at $49.95. (We suspect this is the same as the ZX81 RAM pack, which seems to contain 16K.)

The TS1000 comes with a starter program tape containing the game of Life, a simple Math tester and a program for calculating Averages. All seemed to work as claimed, though the instructions are printed so small they will boost the business of the ophthalmic-profession. The programs are presumably included to show novice users some of the capabilities of the TS1000.

The TSlOOO will no doubt run any peripherals designed for the ZX81 such as the printer and forthcoming modem. We cannot be sure what will happen if any of the third-party memory packs are attached, but suspect that they will work satisfactorily.

The new machine can be faulted for using the same loose jacks as the ZX81 for power and cassette connections. We experienced one or two glitches, due to jacks being only partially seated. This could be especially difficult to sort out for the novice user. Similarly, the adjustments to the television set may be quite complicated. We had to adjust the brightness, contrast, fine tuning, horizontal hold and vertical hold-in short, everything but vertical height and linearity.

To give an appreciation of the serious capabilities of the TSlOOO, we can best present some examples. First, we have found it possible to put the Hooke and Jeeves functions minimizer (“Micro Mathematician” IA Mar 82) into the TSlOOO without need of the extra RAM pack. However, we did drop REMs and also simplified the PRINTs. The resulting program can minimize simple functions of up to 20 parameters. More complicated functions reduce the space to hold data, thus reducing the number of parameters allowed.

Running in FAST mode, the TS1000 approaches function minima at a respectable speed. Moreover, its arithmetic using 4 bytes for the mantissa and one byte for the sign and exponent-usually allows functions to be accurately evaluated. This is not the case for many, much
more expensive, personal computers. The IBM PC running Microsoft Basic, for example, cannot compete for function accuracy (in single precision at least) with the TS1000/ZX81 in such calculations as log (1 + epsilon) or sin(n PI + epsilon), where epsilon is very small and n is a
whole number. This is simply because the arithmetic used in the Microsoft Basic has a smaller mantissa, so that the calculations used in approximating log or sin cannot be carried out without losing accuracy.

Another calculation that fits easily into the TS1000 is quadrature-the evaluation of definite integrals. An important integral is the one defining the area under the normal distribution. P gives the probability that a random normal variate having mean zero and variance 1 will lie between a and b. Any random normal variate x, having mean M and standard deviation s can be transformed.

By careful programming, we do not have to store the m function values, but can calculate them as needed. The whole program for m-as large as desired- can be easily fitted in the TS1000.

For smooth functions such as the normal distribution, m need not be large. The TS1000 can compute normal probabilities in a few seconds, even in slow mode. For functions with many ups and downs, m will have to be correspondingly larger.

The third program used to test the performance of. the TS1000/ZX81 was a numerical linear algebra package. Here we needed the 16K RAM pack. The machine was then capable of handling quite large problems (up to 20 by 20 matrices) requiring the solution of linear equations; linear or nonlinear least squares; matrix inverses or generalized inverses, and matrix eigenvalue problems.

This program package was implemented on the ZX81 first, but loaded on first try in the TS1000. It is worth noting that we tried putting these programs on such small machines only as a test of capacity. The use of tokenizing in the Sinclair Basic is such that a 16K memory on the ZX81/TS1000 allows user programs to operate that could require twice that memory on other microcomputer systems. The success of the ZX81 implementation was such that we took it to the Society for Industrial and Applied Mathematics (SIAM) Linear Algebra Meeting, where it attracted much interest.

The Timex Sinclair 1000 adds to the range of microcomputers available to consumers. Its strength are the solid Basic interpreter, a well-prepared manual, good computing speed and low price. Its weaknesses-the same as those of the ZX81-are the flimsy hardware and awkward keyboard. The lack of true data storage is also an obstacle to data processing, such as bookkeeping or text editing. The TSlOOO will certainly find a use as a learning tool and as a calculating engine. Buyers who purchase it for these purposes will probably be well satisfied with
its value for money.