VLSI Technology Inc, commissioned by Olivetti’s 80%-owned Acorn Computers Plc to manufacture the ARM Acorn RISC Machine microprocessor for the Cambridge company, is taking the part very seriously indeed – so much so that it has designed and brought to market three support chips for the VL86C010. The VL86C110 is a memory controller clocked at 24MHz, with three levels of access privilege supporting content-addressable paged memory, enabling the RISC Machine to access up to 4Mb of memory using 1M-bit memory chips. The VL86C310 is a RISC video controller supporting up to 640 by 480 pixels at a 24MHz pixel rate, and putting up 256 colours from a palette of 4,096; it also supports one, two, four or eight-channel stereophonic sound. The VL86C410 is an input-output controller with four 16-bit counters, bi-directional keyboard input and seven peripheral channels. Samples are available now with the memory controller costing $23.60, the video controller $20.24 and the input-output controller $19.29, for 1,000-up in each case. The Acorn Risc Machine itself is a 32-bit microprocessor with just five instruction types, each with an associated condition code, all of which execute in one 150nS cycle.It has 25 32-bit registers – rather fewer than most RISCs, and 32-bit data and 26-bit address buses with an 18Mbyte-per-second memory band-width (CI No 251). It implements a load-store architecture with part overlapping conditional instruction stream, to deliver an average 3 to 4 MIPS. Fabricated in 2 micron CMOS, it has a 10MHz clock, but 16MHz versions are planned. An development system for the IBM XT or AT is available from the San Jose, California fabricator of the chips that has 8MHz 86C010, 4Mb and interface logic for $3,000, plus $500 each for an array of language compilers for the ARM – Cambridge Lisp, Prolog, Fortran 77, C, Basic.
