Classic programming

Well, I wrote a very big program in 1996 or so in Borland Turbo Pascal. I later updated it in Turbo Pascal for Windows. Later, I ran it on a Linux host using VMWare and Win 2K, but didn't have a way to make any updates. Then, mercifully, fpc came out, specifically for porting old Borland and DEC Pascal programs to the native Linux environment. (I have used the p2c translator for very small programs, but had zero confidence it could handle a major program.) fpc worked AMAZINGLY well at handling a complex set of Pascal files with units and separate compilation. Once I got it running, I fixed a few problems that had been there for some time. This program is a Gerber file to raster converter that I wrote originally for my laser photoplotter. The original version generated plots directly to the plotter using an ISA-bus DMA card under Windows 95. It was all user-mode code and programmed the DMA controller chip. When I moved to 32-bit Windows, it was impossible to determine the physical address of the data buffer, so what I did was create a raster file on Win 2K, and then send the file to the Win 95 computer for plotting. The advantage of the Win 2K environment is HUGELY larger memory space, which was always extremely tight on the Win 95 system. The program has bitmaps of all the defined apertures in memory, and they add up. Since the Win 95 computer was eventually going to die, I replaced it with a Beagle Bone computer, and have a filter that run-length compresses the raw raster output. The Beagle Bone's PRU microcontroller uncompresses the run-length compressed data in real time as it is spoon-feeding the plotter and simulating the old DMA card. It has to feed a pixel to the plotter every 5 us. Well, kind of went off on a tangent there, but that's a case where a really old program got renewed, cleaned up and prepared for another couple decades of life. Jon