Date: 27 Sep 1995 From: Oliver Kellogg To: Jaap van Ganswijk Subject: Re: Chip Directory >Interesting, I can't remember having heard of them before... >They are quite expensive, I guess. Or are there also commercial versions? >Can you explain what the 'MIL-STD-1750 family of processors' is? This is definitely a very-special-purpose chip. I think the total number of users can't be more than a couple dozen people. There are no commercial (non radiation-hardened) versions, and AFAIK prices start at US$ 5000 per chip. I am appending some info on the 1750 architecture. Cheers, Oliver -- The MIL-STD-1750 is a microprocessor architecture standard (by the U.S. Air Force.) The standard encompasses not only the instruction set, but also things such as floating-point formats and operations, interrupt structure, I/O calls, and hardware signals. The 1750 is a 16-bit architecture. In its basic layout, the processor can only address 64k 16-bit words. The instruction set is somewhere between RISC and CISC, and has been designed with special regard to hard real-time applications. An MMU for addressing up to 1 Mwords is optional, but it functions non-transparently (i.e. requires explicit programming for page changes.) Address counting is a bit unusual on the 1750: the unit of address is 16 bits, thus "addr+1" is 16 bits above "addr". In other words, it is not possible to address bytes. (However, there exist special instructions for Load/Store Upper/Lower Byte from a 16-bit word. ) The peculiarity about the MIL-STD-1750 is that most of its chip implement- ations are manufactured to endure cosmic radiation and radioactivity. These chips are therefore used mainly in military and space projects, and nuclear power plants. Examples of implementations are: McDonnell-Douglas MDC281, Fairchild F9450, IBM GVSC, Performance Semiconductor PACE, Marconi 31750.