Chicony NB5620

About the laptop

NB5620 with Okolopoly

 There is very little known about this equipment; i got mine from second hand, and including all what i digged out from the wast Internet, the information materializing in the actual equipment (One laptop plus one power supply unit) still weighted more. The information i list here is either my own find, or collected from a few summaries (Mostly battery selling sites).

Specifications

 My particular unit was probably thrown out long before i got it due to it's HDD failure. It had not got any expansion (So no coprocessor, and only 640Kb of RAM). Otherwise it works OK with a(n old) standard 110Mb laptop HDD. The LCD panel is a little dim and sometimes has stripes across it, probably due to the early design.

Playing around - Ökolopoly

 For a nice demonstration i had an another extremely rare relic: An original boxed copy of a German game Ökolopoly. Well, it fits me well, too bad i do not speak German, and had not got any serial mouse around... The game was released in 1989 (See disk image below), and offers nice EGA graphics. The package contained a demo (!) diskette - yes, that massive box and manual came with just a lousy demo (Or back then even a lousy demo did worth such attention - well, you decide), then you could order the full version. The demo was on a poor quality blue 720Kb disk while the full came on two which work fine even today. This software is so rare that apart from the board game from which it was converted you are not likely to find any other information on it.

 One of the other pictures below show a 3D attempt in QBasic (It was out under some name like Cheetah RPG experiment in the Running Cheetah Software era). It may seem sluggish with that 4 FPS, but it is still respectable considering that it uses floating point for the 3D (which is emulated by the 20MHz main CPU as there is no floating point unit installed), and that a Pentium 133 failed at a miserable 6 FPS with the same.

Okolopoly game disk label Okolopoly playing Okolopoly manual and disks QBasic struggling with 3D King Cheetah pic. shown with LxPic

Using the Fn keys

 You will not likely see any manual for this laptop any more, so to save you some time and nerves, here i list the most important Fn key combinations (I figured these out myself as well). If the key has a blue function printed on it, then holding the Fn key while pressing it will activate that (Like the '+' and '-' symbols on the arrow keys). Most of the keys however lack this information. Here are those keys:

Diassembling

Popping the hood

 Sometimes you may need to replace something (Like the HDD) under the hood. So here i provide some details, and well, pictures, of what you will find in there. Note that this procedure is not easy, it needs care and patience, so it is not recommended if you have no previous experience working with hardware.

 First of all you need to locate all the screws. To do it right even before that you need to remove the keyboard unit. Two screws hold it in place which are covered by small plastic pieces. To remove the unit, you also need to unplug the wiring from the underlying circuit board. Do not pull these with force, try to slowly work them out from the connectors. Note that plugging them back might be a little tricky! When the keyboard is loose, you can turn the box around, and after removing the rubber foots, unscrew all screws what you see including the three ones sitting under the battery. Those all fix the top part of the housing.

 Now you should see a mess of wires and boards sitting in the bottom of the cover. The two black connectors on the big green board (The video board) were where the keyboard was plugged in. Also notice the two white cables going to the LCD, and their initial placement - replacing them to allow the cover shutting again is the trickiest part of the whole assembly (You may help yourself with some glue tapes. Once for me it took more than a half hour to get over this part).

 To get any further you will need to remove the power distributor unit as it also covers the fourth screw fixing the hard disk, and it's connector. Apart from the yellow "spaghetti" cable, you should disconnect everything from it before (And the black cable pack going to the LED board as well). Two screws hold it in place. After you had done with these, gently lift it from the middle; note that a little force may be necessary. This unit is plugged in two connectors on it's bottom. When replacing you need to be very (!) careful to not bend or break those pins!

 Now you can replace the hard disk if you want to do so. The notebook should accept any old style laptop HDD at least up to a size of 110Mb (The Maxtor one you see here is a 110Mb one). Note that you must determine the appropriate BIOS settings for the HDD since it does not offer automatic detection.

 At this point if you want, you may even remove and check out the two boards consisting the actual computer, but beforehands be sure to record your HDD settings in the BIOS since it will forget if you seperate the two boards. I can not help you this case as i do not know the specifications of the original Conner HDDs. Alternatively you may try to reverse what you just did, hope successing (If not, well, i am in the need of a RAM expansion unit, so as you happen to have a defective laptop i won't ask much if i borrowed it, not? :) ).

Screws holding the keyboard Keyboard wiring Back side of the laptop Popping the hood Video board and the back of the motherboard The motherboard

Warnings regarding usage

 There are a few things you may need to pay attention to if you want to longer the life of your old equipment. First the fact that it tends to get a little hot during operation. Do not place it on heat - insulating material for long (like what i did above for the photographs). The power supply unit is even more prone to this, you might even want to keep it in some ventilated place during operation. An other problematic part is the power supply connector on the laptop's back. This part seems to be a little fraigle, and to make things worse the power cord needs considerable force to plug in or out. If possible, do not do these if it can be avoided (Or prepare to resolder loosened contacts on the power distributor board... Or as i told, i really need a RAM expansion unit :3 ). I store the laptop with it's power supply left plugged in it (but of course not on the mains).

Programming speculations

The internal RAM's size

 As it is certainly visible on the motherboard, the laptop contains eight RAM chips soldered on it. This means that they should be of 128Kb capacity each (All chips are the same), which sums up to a total of 1Mb. It is still unclear how the 384Kb UMB area can be accessed: the BIOS does not offer any feature enabling RAM there (Except for shadowing), and tries shown that normally there are no writeable areas enabled above 640Kb (Except for the video RAM, but that's an entirely different thing). UMBPCI and the few other existing hardware UMB providers does not support this laptop.

Programming the Cirrus VGA

 It was a nice find when browsing the Ralph Brown Interrupt List i found functions relating to Cirrus video BIOSses. This includes a bunch of references regarding the operation of LCD panels. It is very likely that this laptop's VGA will also answer these calls, so it is programmable from software (This mostly means it should be possible to access those functions the Fn keys provide). This still needs verification though, but why wouldn't it work?

 It should be noted however that the LCD may or may not like tricky VGA programming. I did not test as the least thing i want is damaging it. It is fine if you keep the VGA standard timings (This means avoiding changes on the Horizontal Total and Vertical Total registers only putting values there matching to the standard 640/720px width and 400/480px height).