★ HARDWARE ★ MONTAGES ★ The proof is in the printing: expand your Amstrad DMP 2000 s buffer to 8K ★ |
| Expand Your Amstrad Dmp 2000 Buffer To 8k (Popular Computing Weekly) | Hardware Montages |
Dave Race explains how to expand your Amstrad DMP 2000's buffer to 8K Amongst other great features the Amstrad DMP 2000 printer comes complete with a 2K buffer, which siores characters sent from the computer and allows the computer to carry on computing instead of having to wait for the printer to finish printing. In fact the actual printer buffer is only half a kilobyte which obviously won't store very much text at all. slightly less than this paragraph in fact. This means that in reality your computer will still have to wait for the printer to catch up with it. Figure two - printer PCB However, I have discovered that it is possible to expand the printer buffer some seven fold, thus allowing reasonably large chunks of text to be sent to the printer without holding up the computer. It should be noted that fitting this extra memory will almost certainly invalidate the Amstrad warranty and so should only be carried out on machines over a year old, or by owners who don't mind paying for any repairs if their printer goes wrong. That warning out of the way, on with the instructions. To begin with ensure that the mains lead is unplugged. It is not sufficient to simply switch the printer off, and you must check there is no paper or ribbon in the printer. Now turn the printer over so you have access to the bottom (you'll probably want to put the lid to one side). You will be able to see six Posidrive screws, three at the front and three at the back, unscrew and remove these - and put them somewhere safe Turn the printer back over and remove the top half; this is best done with the friction/tractor switch in the friction position. Lift the top half up, tilt it forward, and you will see that there is a ribbon cable going from the push button panel to a printed circuit board in the bottom half. Unplug this at the PCB end and you will be able to remove the top completely. Figure one — J3 viewed from solder side of board If you examine this PCB you will see six more leads going 10 it. Remove all these carefully, making note of where each goes. You also need to unscrew the two Posidrive screws that seem to be holding the Centronics connector in place. The PCB can now be removed by lifting it up from the rear and pulling it out backwards. Place the PCB on your work-surface, preferably on a piece of cardboard to give it some protection. It should not be placed on a metal surface. Remove the 2K Ram chip (see figure two). This is best done by levering the chip up at both ends in turn with the flat bladed screwdriver until it comes free. The 8K chip goes in the socket you have just emptied. If you look closely at the chip you will see it has a small indentation at one end, which must be orientated the same way as in the diagram, ie, with the indentation towards the rear of the board. When inserting the chip it is very important to check that no legs are bent. It is also a good idea to touch something that is earthed before hand ling the chip as it is quite sensitive to static electricity. The printer can be put back together now in the reverse order to' the instructions above, being careful not to damage any of the cables going to the PCB. Once back together power the printer up and try sending a listing to it. You should be able to see quite an improvement.
|
