|★ HARDWARE ★ MONTAGES ★ Upgrading the DMP 2000 printer ★|
|Upgrading the DMP 2000 printer (Computing With the Amstrad)||Hardware Montages|
FRANK PHILBROW does it himself and quadruples the buffer size
AFTER reading the review of the Amstrad DMP 2000 printer in the May 1986 issue of Computing with the Amstrad I rushed round to my local store and bought one.
I connected it up and started to use it with my favourite word processor. The results were very good, but I found that I was waiting for the printout when I wished to process the next item. Being impatient and rather nosy I decided to take a look inside the printer.
Having established from the technical information in the handbook that there is a 2k buffer I found the relevant chip - a 6116 24 pin static RAM - in a 28 pin socket, and there beside it a space for a two-way selection jumper.
Tracing the tracks of the PCB showed me that this printer can be upgraded easily by replacing the 2k RAM chip with an 8k one and changing the jumper on the PCB.
This can be achieved either by a simple cut and the insertion of a new link, or in certain cases by moving a jumper.
The installation of this upgrade may invalidate your guarantee, so check first with whoever sold you the printer. I was assured by my retailer that he would still honour it if the change was neatly done.
The resulting modifications provide a buffer that will hold four pages of text compared with the original one. Anyone who can link two adjacent solder pads with thin wire and carefully replace a CMOS RAM chip can improve the printer throughput fourfold.
The alterations involve the following simple steps:
Firstly ensure that the mains lead Is unplugged and turn the printer upside down. Then remove the six screws from the bottom of the case. Turn the printer the right way up with the back facing you.
Carefully lift the top cover - the mains cable and switch may stick slightly in the top. Then unplug the ribbon cable going to the cover switches from CN3.
Put the top cover on one side and remove the two screws from the Centronics plug - the inner one is not a self-tapping screw.
Note the position of the missing jumper J3 - indicated in the photograph. If you have a jumper link at J3 change it to the right link and move on to the chip itself. The centre and left pads are connected on the underside of the PCB.
Gently lift the PCB upwards and backwards to view the underside of J3. Then with a sharp scalpel cut the link between J3's centre and left pads and solder a link between J3's centre and right pads.
Carefully replace the PCB and the screws in the Centronics plug. Remove IC10 - the 6116 chip - and insert the 6264 making sure that the notch faces in the same direction, that is to the rear of the machine.
Replace the ribbon connector and the cover, and finally replace the screws in the base.
That completes the upgrade. Now you should carry out a self-test by switching on the printer with the LF button pressed. If all is not well carefully check your work and that the IC is correctly inserted with no bent legs.
Once the test works switch the printer on as normal, load in your favourite word processor, print a long item and notice the speed at which the prompt returns.
If you have any qualms about making these alterations it might help you to know that I carried out the upgrade to my printer over six months ago and it has functioned perfectly ever since.