INMC 80 News


May–September 1981 · Issue 4

Page 59 of 71

It would not be out of place to list here the various control codes and their functions:

Code 02 (CTRL B) sets bidirectional print. This mode gives maximum throughput – say 65 chars per second!

Code 03 (CTRL C) sets unidirectional print. This gives best alignment for columns of figures. The command is obeyed immediately on receipt.

Code 04 (CTRL D) sets double width printing. This character is queued in the buffer, and only takes effect in its appropriate place. It is automatically reset at the end of a line.

Code 05 (CTRL E) sets single width characters. All lines start out in this condition, so you must reindicate by a CTRL D if you want double width after each line feed.

Code 08 (CTRL H) Backspace. This will only backspace within a line. It will not pass a Line Feed (0A), a Carriage Return (0D) or a Form Feed (0C).

Code 09 (CTRL I) Horizontal Tab. This will cause the print head to print spaces until it is at the next column which is a multiple of 8.

Code 0A (CTRL J) Line feed. This prints any preceeding characters in the buffer, and advances the paper by one line.

Code 0C (CTRL L) Form Feed. This causes 6 line feeds in succession.

Code 0D (CTRL M) Carriage return. This causes any preceeding characters in the buffer to be printed, and if the strap option is set in the IMP, causes a line feed.

Code 1F (CTRL _) Graphics Mode. Prints out the Buffer, and puts head at lefthand side on a fresh line. Then it interprets the next 760 Bytes as a dot pattern, and prints them across the page. At the end of the line, it feeds enough for another graphics line to join below the last one, and the IMP returns to the normal type mode. It is necessary to reinvoke the graphics option at the start of each line of graphics.

These are the options, with the addition of the self test on reset. Without any doubt, the Imprint is a very worth while addition to any IMP. The alteration to the rub out character to allow continuous bi-directional printing alone allows the throughput of the IMP to be nearly doubled (38 chars per sec to 65 chars per sec from my measurements!) and may put off the evil hour when a faster printer becomes essential. Those who have had to wait two hours for the latest edition of a printout will know what I mean (and sympathise?).

The Imprint comes with a well commented and well printed set of documentation. There is one error in it that I found. The reference on page 3 to code 04 should be to code 02. With my copy, there was no mention of how to put the EPROM in position. I hope that this will be rectified shortly. To open the IMP, you will need a 3/32″ Allen hex key. Unplug the IMP from the mains (dying is something you usually only get one chance at!) and open the two little black studs on each side with the Allen Key, which can be got in any good toolshop or engineers providers. Very carefully, slip the case off, and lay it on its back beside the machine. It is still connected to the IMP by a loom of wire, so try not to put too much tension on these wires. Then, with a long handled fine screwdriver, working from the front of the machine, insert the screw driver under the EPROM, which is about 1/3 of the way across the machine, pointing front to back. Very gently, you can twist the blade to free this EPROM, until it can be lifted out. It should be held only by the ends, not by the pins. The new EPROM can be placed in position, holding in the same manner, with the orientation dot or dimple on the end facing the print mechanism, and pushed down gently into position. The old EPROM should be placed into a piece of antistatic foam, or foil wrapped airfoam, and kept until a use arises for it. It could be reprogrammed with a new character set for an N2, or an N1 with Econographics. Having inserted the EPROM, now is the time to lubricate the innards of the IMP. A drop of oil on the polished guide rail, the frame edge, the helical cam, and the ribbon driver are all that is required. Now put the top back, screw in the screws, thread the paper, and plug in. Turn on, hit reset, while holding down the Line feed button. The machine will enter self test mode, and print away busily for about 25 seconds. The rest is up to you!

The Imprint is available from Interface Components (and possibly other Nascom distributors ?), costing #30 plus VAT. The author, David Parkinson, is to be congratulated on having got so much into so little.

Page 59 of 71