T1200XE belongs to the first generation of Toshiba portables equipped with 2.5-inch hard drives which allowed to make the machines smaller and lighter (3.6 kg). It has 12-MHz 80C286, at least 1 MB RAM (up to 5 MB) and a gorgeous 9,3-inch sidelit blue-and-white LCD. This LCD has a resolution of 640×400 and it is combined with a graphics chip that can utilize the full resolution for text and graphics (32 kB of video RAM).
“Grayscale” in 320×200 is emulated using 1-bit 2×2 patterns so the picture looks more like on Hercules cards emulating CGA. On the other side the screen is very sharp and blue text and backgrounds look cool.
Switching from passive-matrix to active-matrix LCDs was a big deal for many. However, not everybody in the mid-90s had enough money to afford a color TFT panel in a new laptop as the price premium was still about $1000. Color passive-matrix screens were a solution for those with tight budged.
640×480 monochrome passive-matrix screens needed about 1.800 transistors to control all pixels (n*2+m for dual-scan). Color active-matrix screens (TFT) with the same resolution needed 300.000 transistors as each pixel is controlled by three transistors (3*n*m). That’s why these screens were so expensive.
Color passive-matrix screens (DSTN) were a good low-cost alternative for everybody who wanted colors “on the road”. This technology needed only about 5.000 transistors for the resolution of 640×480 (2*3*n+m). The result was not exceptional but it was good enough for many productivity applications where slow response rate (300-700 milliseconds) was not a problem.
Unfortunately, quality varied a lot between DSTN screens. Although some had a very crisp picture with shiny colors on par with today’s cheap TN panels, some suffered from significantly poorer contrast, washed colors and color bleeding.
The machine on the right is in fact my first own PC compatible laptop. I hated the screen so much back then and I envied others their color-screen portables. The machine on the left has the best DSTN panel I’ve ever seen in the laptop. Although both machines use the passive-matrix technology the difference in picture quality is huge.
UPDATE: (1) I was not completely right with the transistor counts – for passive-matrix displays, there will be at least twice as much transistors (one on Vcc and one on GND for each row/column to output both logic levels 0 and 1). (2) I also forgot to mention that passive-matrix screens don’t have transistors in the panel itself. There are special chips on a separate board which makes the solution much cheaper in comparison with TFT (which has multiple layers with tiny transistors inside the panel).
Apple IIc was designed to be portable. That meant that the computer could be easily carried from work to home or anywhere else where you had a power socket and a composite screen (or TV). I knew about the LCD option offered by Apple but I didn’t know that there were complete kits to make the computer usable everywhere.
A true mobile user could enhance his Apple IIc with a passive-matrix non-backlit LCD (connected to the video port using a ribbon cable) and an external lead acid battery. There were also bags specially designed to carry all this stuff safely.
This option was not very successful, though. Not because of its weight around five kilograms – that was adequate by the standards of the era (there were people carrying Osbornes). The main problem was the LCD screen which could produce a good picture only under direct sun light. The contrast was extremely low and the screen was hardly readable in a dimly lit room. I’ve tried few different laptop LCD screens from the same generation and my eyes almost bled after 30 minutes of work.
Having three separate parts was also not very convenient for frequent travelers. The screen was not designed to cover the keyboard when the computer was being transported and you always had to attach the battery. The first generation of laptops started to appear at the same time. Although they were as heavy as this kit, they had all components in a single briefcase-like package. In 1985, you could buy Bondwell Model 2 (a cheaper CP/M laptop with 64kB of memory) or one of those PC compatible laptops which started to appear at the end of the year (like my Bondwell Model 8).
Although 640×400 (“double CGA”) LCD screens usually could display only “black” and “white” (so the 320×200 4-color mode was handled using multiple 2×2 1-bit patterns) this was an exception. The screen on Olivetti Quaderno can display four shades of grey with a good contrast. It reminds me playing games on old Game Boy handhelds…
IBM PS/2 Model P70 (1989) on the left side and Toshiba T2200SX (1991) on the right side. The IBM machine is equipped with a gas-plasma display and Toshiba has a typical side-lit passive-matrix LCD. The photo can hardly show how superior the plasma screen is. Its black is so deep that it cannot be beaten with any modern LCD. It is as fast as CRT monitors (unlike passive-matrix LCDs with 300ms response time) and as sharp as active-matrix LCDs (that were introduced a year after this machine).
There are no plasma screens in laptops today so where was the catch? It was in power consumption which was significantly higher. Typical machine with a gas-plasma display was either AC-only or with battery life usually up to one hour. Active matrix displays started to be affordable in 1992-1993 and with their color capability and lower power consumption they pushed plasma screens out of the market. Until then gas-plasma displays were the hi-end choice for many portables.
A friend of mine gave me this interesting piece of hardware. SGI 1600SW Flat Panel was introduced in 1998 which was quite before LCDs became common. There were not so many LCD screens for desktop computers before this and those which were available usually had smaller resolution – 1600×1024 is not bad even by today’s standards.
