Imlac assembler almost ready...

Ben Franchuk wrote: <snip> Clearly you haven't looked at the Imlac schematics! Engineers designed lots of hardware of the same era without resorting to the kinds of tricks used in the Imlac. Did you know that each Imlac had to have RC networks that control its clocks and timing signals tuned by hand, for each unit? The components used were garden variety ceramic caps with very loose tolerances, not poly or other higher quality components. The issue here is the quality of hardware engineering. HP machines of the same period are vastly better engineered, as are many other machines To suggest that nothing better was available to the engineering team at Imlac is laughable at best. The vector display has nothing to do with the design quality whatsoever! What makes you say something like this Ben? For what the Imlac did, when it did it, VECTOR was FAR SUPERIOR to raster displays. Please note, the Imlac had a 1024 by 1024 addressable display, prior to 1970. This greatly exceeds what was possible with raster graphics at the time, and the Imlac was designed for calligraphic applications where its short vectors made for a mugh higher quality display than a pixellated raster display of the same resolution would have. There is also the fact that manipulating raster display is far more computationally intensive than manipulating a vector display list. The Imlac CPU would not be well suited for raster graphics at all, but its more than sufficient for its intended use. The problems with the Imlac are issues of engineering quality, like the total lack of decoupling capacitors, poor grounding, and poor logic design. This is also reflected in the manufacturing of early units in the failue to wash the etchant off the boards (many Imlac boards now have fuzzy green etches, or no remaining etches at all) and poor metal preperation prior to painting, and the fact that the design was very quickly repackaged as the PDS-1D's. The CRT used in the Imlac was common enough in its day, and that same tube was also used in much higher quality products as well. The last comment about the display refesh is hard to understand. The Imlac does not use a storage tube, and it must keep the display refreshed in the same way as any raster graphics display does. I'm not at all sure I understand your point here, can you expand on this point? If your suggesting re-implementing the Imlac with a raster display, this is totally impractical. My ReImlac project will use a real vector display, as that is the only way to duplicate the capabilities of the original machine. Remember, the Imlac does not have jagged vectors even when drawing at any angle. To try to do this on a raster display would reqire a resolution far far greater than 1024 by 1024. The anti-alising along would take more logic than the full original machine does. On the other hand, a Wells Gardner vector monitor is more than able to display the vector video from an Imlac exactly the way a real Imlac does. So will most small oscilloscopes, or even a modified TV monitor. Small vector display monitors are fairly common on eBay at very affordable prices. So whats the problem with a vector display? To be true to the original, I'm sticking with a true vector display. After all, I'm quite addicted to vector (and point plot) displays, and this was my main attraction to the Imlac. If this were replaced by a raster display, you might as well run a software emulator and not bother re-implementing the Imlac in hardware at all. The vector display of the Imlac is a thing of beauty and is a huge part of what makes an Imlac so unique. To call this "...the real problem..." is heracy!