Scor­pio News


October–December 1987 – Volume 1. Issue 4.

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These three problems are the most major ones and (sorry to boast but..) they are ones which I had already dealt with my own version. My complaint regarding the printer dump is also one for which I have devised a solution but I have not yet written the code. When dumping a line to the printer it is necessary to draw three screens on the SVC to get the relvant width. Each screen, however, contains parts of about 30 lines. This program draws all three screens for each line thus plotting each one thirty tines. Consequently it is very very very slow. If the data for all thirty lines were “cached” in memory it would be very much faster.

Another (and perhaps more major) criticism is that no effort is made to ignore totally blank areas. The result of this on a small-ish board, like the demo. file, is that the printer spends several minutes moving the print head from one side to the other and doing nothing with it, even to the extent that I began to wonder whether the machine bad crashed. Surely a the largest Y co-ordinate in the file is 260 there no need to start dumping from 800 down!

A rather obscure change is that pads now have a side code. This is necessary for double sided edge connector pads and nothing else. However, for some strange reason it refers to all pads with the result that holes do not apparently go through the board.

In order to fit the extra program size it now consists of several chained files for the various bits. I have had to do this too, but I think the way they are split is rather silly here and it results in inconvenient command structures and rater slow operation.

Well those are my moans. As I commented regarding the simple version, it helps to be patient with this one, but the basic concept is good, and at this low price you pay your money and make your choice.

The author of the PCB software replies

I would like to comment on the so called ‘Review’ of the SVC PCB program written by myself. I wouldn’t have minded so much reading this ‘review’ if the person who written it had done the review properly, instead he waded straight in to the complaints and failed to mention fully the features of the program and its case of use in relation to its price (see the advert elsewhere in this issue). Instead he just compared it the the small pcb program issued co the Scorpio Systems Disks, which by no means compares anything of all to its big brother.

I do not accept bis argument about the track routines not being able to move outside the currently displayed PCB segment since I did write a version which did allow this feature. Unfortunately this process, where all the tracks had to be checked for clipping against the edge boundary of the screen before they could be displayed, dramatically slowed down the display when it was being updated, and after the initial testing of the program it was decided to use the simpler track routines to keep the speed of the program up.

Other mistakes in his ‘review’ included the inability of the program to plot 20 pin ic layouts, the case being it has always been able to do so, the only area where this is mentioned is in the on-line help file where a syntax error has occurred. He also makes no mention about the numerous types of pads and symbols which are available (12 in total).

Also I cannot make any sense why he doesn’t think that a side flag is required for the pcb symbols – surely if a person requires a through hole on a double sided PCB they would put the appropriate symbol on both sides at the same co-ordinates. This also leads me onto his idea of displaying both sides of the PCB at the same time, if this was done on a fairly packed pcb all this would lead to would be unrecognisable green patch on the screen, instead why not just use the ‘flip side’ key to turn the PCB over for a brief look at the other side.

The only one area with which I could agree with in the ‘review’ concerned that of the printer routine being very slow. This has been cured with each of the PCB segments now being displayed only once and stored in a temporary file which is dumped to the printer as a whole to produce a 1:1 scale quickly is order to review the PCB through its design stage, or to print either to the SVC or printer a complete compressed view of the entire PCB quickly.

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