4004 Development System

On 03/13/2014 08:03 PM, Eric Smith wrote: SMS was the designer, all the DIE in the SMS300 were in fact Signetics. At that time Signetics had the foundry and bipolar was their thing that they did very well. No, not 125, I said 150nS! Apparently it took three edges for certain things and the clock was 8mhz. The instructions were executed at a rate of one every 250nS. The difference in timing was due to some internal pipeline. Also it was partly due to the IV interface (their unique IO) and its latency. To say the 8x300 was very unique only scratches the surface. Its associated IV IO parts were equally odd as well. It was bipolar Schottky **, LSI and fast by any standard for the day. Until the early 80s it was either that or 6700 or 2900 bit slice or random logic for speed. At that time signal processing, floppy or hard disk IO and other tasks requiring high arithmetic and logical speed it was the game. Basically other than a small (8bytes if memory serves) register file the 8x300 had no ram nor way to address any the expectation was very little internal storage of intermediate work before output. So most programming was input massage to some small extent and emit while keeping some form of small history (for doing a CRC). Often if intermediate storage of large amounts of data were needed an IV port would be use to create an address and the other ports would serve as data bus under program control. It was awkward but speed made up for it. There are very few micros that stand out as unusual, The 8x300 was one. In my mind the the others were the 6100 (PDP-8 IO is unlike all micros), the 1802 for its simplicity and also unusual IO, plus the TI9900 with its CRU IO (IO address as variable length bit strings). Most of the early microcomputers like the tI1000 were very distinct 4bit data and 8it instruction Harvard machines. The current PIC12,16 series are a direct outgrowth of that. Allison