While searching for the Christmas decorations in the computer graveyard that is our loft I came across my old Psion MC400. This was the spiritual ancestor of the NetBook; a laptop, based on the SIBO operating system that could run for 60+ hours on a single set of batteries.

Psion MC400

Psion MC400

It was a ground breaking machine at the time of its release in 1990, and even today it has some features that cannot be matched by any current machine.

There were four machines in the Mobile Computer (MC) range:

  • The MC200 ran EPOC and had a letter-box 640x200 screen
  • The MC400 ran EPOC and had an almost VGA 640x400 screen
  • The MC Word added a ROM-based Word Processor to the MC400
  • The MC600 had the 640x200 screen but ran MS-DOS 3.2

The MC600 had 768 Kbytes of RAM and an internal 1 Mbyte RAM disk. The MC200 and 400 had 256 Kbyte of RAM and 256 Kbytes of ROM. However in practice the OS and applications ran off an SSD, presumably for easier upgrading.

The MC200 used a Supertwist LCD that displayed text as blue on white, while the 400’s black on white display used a Retardation Film LCD. The MC600 had a black on white Retardation Film LCD, the same size as that of the 400, but with a resolution of only 640x200. None of the displays were backlit and the contrast was much lower than that of modern displays.

Under normal office lighting the MC400’s display is perfectly usable, but on a lap, with your feet up, in front of the television the lighting has to be arranged with a certain amount of care to ensure the display is comfortable to read. That the angle of the screen is not adjustable doesn’t help, though the contrast is adjustable.

The display shows quite a lot of bleed from the corners of dialogs. This is specially noticable from vertical scroll bars that contain a lot of grey. This was a common problem on large LCDs in the late 1980’s and was caused by the way the pixels were addressed. Although ugly it doesn’t effect the usability of the screen.

The lack of backlighting and the slow CMOS processor (a 80C86 running at 7.68 MHz) means that the MC400 is very frugal on battery power. Psion quoted 60 hours of continuous use from one set of eight alkaline AA cells. The smaller display of the MC200 meant that it could run for 75 hours. These were maximum figures based on no use of peripherals such as the serial port.

There were a number of power options. The machine came with a removable battery holder that took eight AA cells. There was also two NiCad battery packs available that could be recharged out of the machine by plugging the mains adapter into the battery pack rather than the laptop.

The MC400’s manual quotes the following battery lives:

  • Ni-Cad 1000 mAh - 25 hours continuous use
  • Ni-Cad 600 mAh - 15 hours continuous use

after a 12 hour charge time.

Currently I have the alkaline battery pack fitted with a set of 2000 mAh NiMH batteries - it will be interesting to see how much usage they provide. I’ve written a short OPL program that monitors the time the machine runs on a battery pack. The system information dialog shows the battery pack voltage but gives no indication of elapsed or predicted run time.

The OPL language built into the MC400 is not quite as extensive as that in the Series 3a or Series 5. For example there is no dialog support, and really strangely, no graphics command - given the machine is GUI based.

The OPL translator is integrated into the text editor and is enabled when a file is saved with the .opl extension. A debugger and a useful reference which lists the syntax of the commands and library calls is also built in.

One of the best features of the MC400 is the keyboard. It is by far the best keyboard I’ve used on any notebook-sized machine. It has full-travel keys that wouldn’t be out of place on a desktop machine. An absolute joy to type on, it makes the MC400 great for wordsmithing. Special and punctuation characters are laid out in a pretty standard manner making it easy to work on program or HTML code too.

Eight special function keys provide the following:

  • Task switching - SIBO is of course fully multi-tasking
  • Delete
  • Home and End
  • Page Up and Down
  • LCD contrast
  • Record (non-functional)

The Record function and the built-in microphone and jacks were for a digital signal processor module which did not see the light of day. Unfortunately without the DSP module the Record button, and the audio note facility in the Diary application do nothing.

MC400 field stripped with a Series 5 for comparison

MC400 field stripped with a Series 5 for comparison

Between the keyboard and screen is a large touch panel. Touching the panel brings up a pointer on the screen in the same relative position. Unlike the touch panel on a modern machine, it represents the whole screen. Touch the top right hand corner and that is where the pointer appears on the screen. Pushing down harder on the panel ‘clicks’ it.

Unfortunately on this example the panel’s digitizer was always a little over-sensitive making the pointer jump about. This made it difficult to use the panel to select text, for example. Luckily there are straight forward keyboard shortcuts for all functions, so the panel is not essential.

Either side of the panel, on the edges of the machine is a door. Each hides two SSD drives - the Solid State Disks used by the S3 and MC families. These were available as ROMs, Flash or battery backed RAM. The adverts at the time said that you could store data on a Flash SSD, remove it from the machine and ten years later it would still be intact. This was true; exploring my old SSDs I’ve found files that were written 12 years ago.

The A: drive holds the system software. the other three drives are available for storage. The ‘System’ disk contained the following:

  • System
  • Text Processor (and OPL)
  • Diary
  • Personal Database
  • Calculator
  • Alarms
  • File Manager
  • The Link
  • Terminal Emulator

The following additional software was also available:

  • Word
  • Spreadsheet

Details of the individual applications will be available on links in the above lists.

In one way the MC400 really shows its age. It only supports filenames in the MS-DOS 8.3 format. Everyone is so used to the more flexible filenames provided by the Macintosh, and latter Windows, that it comes as quite a shock to realise that only a short time ago we were restricted to just eight characters for filenames on many machines.

On the whole the MC hardware was reliable, though early in its life this machine succumbed to that old Psion bug-bear - the disintegrating screen ribbon cable. There are suggestions on the Web that this was not unknown with the MC series. (Unfortunately while taking the photographs for this article the machine began to show the early signs of the cable failing again.)

Parallel and Serial Port in Removable Module

Parallel and Serial Port in Removable Module

At the back of the machine are two removable modules. One is a dummy, the other contains a serial and parallel port. The dummy module could be replaced by a V22bis modem or the DSP module. There was also a high-speed serial port hidden behind a door on the left side of the machine. This could be connected to a PC card for high speed data transfer with a desktop machine.

Finally, on the right-hand side of the machine another door hides sockets for power and sound in and out.

  • Size: 49mm x 314mm x 227mm
  • Weight: 1.9 Kg
  • Screen: 640 x 400 pixels (black and white)
  • Memory: 256K RAM, 256K ROM
  • Drives: 4x SSD (MS-DOS compatible file system). One used for System.