Many years ago I dreamed such machine as TI-89 is: low priced pocket machine that can do symbolic mathematic, contain standard microprocessor and has enough large screen for nice games. The only thing it lacks is embeded modem.

ZX Spectrum (1982) is a machine 16 years older than TI89. Comparing ZX Spectrum with Pentium !!! 500 is silly, but comparing of ZX Spectrum and TI-89 is worth attention.

The CPU on TI89 is Motorola 68000/10 MHz. Spectrum uses Zilog Z80/3.5 MHz. Taking in account sizes of instruction, TI89 is twice faster.

Both machines have small ammount of RAM memory, ZX Spectrum has 48 K, TI-89 has 256 K. Assuming that Motorola 68000 requires more memory than Z80, programmers on both machines must care about memory resources.

ROM on TI-89 is very huge, about 1 M. It is written in C, and contains many mathematic and general purpose routines. ROM on ZX Spectrum is only 16 K long, and contains small, but enough powerfull BASIC interpreter.

TI-89 uses flash memory for storadge. It is fast and limited. ZX Spectrum uses tape recorder, very slow, but capacitty is not limited.

Graphic is better on ZX Spectrum. The resolution is 256x192 while TI89 has 160x100. Converting pictures can cause big losses. Also, ZX Spectrum has colors without software tricks. TI92+ has resolution of 240x128, much closer to ZX Spectrum.

Sound on Spectrum is limited, but still better than on TI89, because Spectrum has small speaker.

Keys are better on TI89, but keyboard layout (QWERTY) is better on ZX Spectrum.

Both machines require purchasing of additional interfaces for connecting with other computers.

The common feature I like on both machines is that it is possible to understand them thoroughly. The dimensions of modern operating systems (Windows, Linux) and software are so huge that one man can not get even 10% of picture of the OS before new release is published. What is purpose of 10000 files in your C:\WINDOWS directory? And, only one of them can contain 1000 API functions. Can you write program to be high top on modern PC, when games like Quake are considered obsolete, and word processors have tons of options?... But, if the hardware has resonable limit, simple man can be in world top. This is a case with TI89, or Spectrum where Phoenix is considered great game, and word processors does not require full programming language included.

The comparation I made proves that writing of Tezxas was hard job, because TI89 is not so much better machine than Spectrum, in some capabilities even it is worse.