A converter

D / A converter Burr-Brown have introduced a 16-bit monotonic D/A converter which incorporates its own calibration circuitry. Known as the DAC 74, it is designed for use in applications that demand high resolution and accuracy and is particularly suitable when the equipment is remotely located, making access for calibration difficult. Such equipment includes displays, frequency synthesizers, automatic test equipment, analytical instruments and high-resolution controllers. Providing either a unipolar ( 0 - 1 0 V ) or bipolar (-10-10 V) voltage output, the DAC 74 will maintain gain, offset and linearity errors to a minimum over the 15-45 °C temperature range. Maximum nonlinearity is specified as +-0.5 LSB, differential nonlinearity is -+1 LSB (maximum), maximum gain error is +0.00075 per cent and maximum offset error (unipolar) is +-40 UV. The microprocessor-controlled calibration circuit is the result of a

Bit-slice development The AmSYS29/10 development system offers significant enhancements to the bit-slice developer. A key option to the system is an integrated logic analyser. The system offers symbolic development of microcode, high speed control-store emulator, target system clock control and logic-state monitoring. During hardware and software integration, AmSYS29/10 reduces debug time by emulating critical parts of the target system. In particular, a writeable control store replaces control-store PROM with high speed RAM and clock control logic adds breakpoint and single-step capability. A single-card microprogram sequencer is provided as an evaluation vehicle for microprogram familiarization and software module testing. When combined with control store and control logic, the microprogram

vol 5 no 10 december 81

development project at Burr-Brown. It trims the analogue output to maintain this accuracy in spite of drift caused by temperature changes and long term effects. The DAC 74 will operate within the temperature range for at least a full year before manual recalibration is required. The DAC 74 comprises a 16-bit latched input D/A converter, which performs the conversion; a stable temperature-compensated voltage reference; an error measuring circuit which compares the D/A converter output to known references; and a microcomputer-based controller that stores the output of the error measuring circuit and calculates correction factors for offset, gain and linearity. The controller stores these correction factors in RAM and they are used to adjust errors when an input data word selected by the user is presented at the input to the main D/A converter. (Burr-Brown Inter-

national L td, Cassiobury House, 11-19 Station Road, Watford, Herts WD1 IEA, UK. Tel: (0923) 33837. Telex: 922481)

sequencer forms a complete microprogrammed controller that is useful for testing and debugging prototype hardware. AmSYS29/10 provides the designer with the industry-standard AMDASM meta-assembler to support microcode development. The recta-assembler allows definition of a mnemonic instruction set for any microinstruction format. In addition, support is provided for an optional high speed trace unit with logic-state analyser capabilities. The trace unit has been designed to allow tracking of microinstructions and the many bus paths found inside complex bit-slice architectures. Thus, the development system provides complete hardware and software tools for the development of microprogrammed target systems. A single Am96/1064 board containing 64 kbyte of dynamic RAM and autorefresh provides memory support.

(Advanced Micro Devices (UK) Ltd, Goldsworth Road, Woking, Surrey GU21 liT, UK. Tel: (04862) 22121. Tel: 859103)

Instant speech one-off component The TDS934 is a set of microcircuits for generation of the spoken word using Triangle's proprietary Instant Speech method. Previously offered only as a complete assembly (see

Microprocessors & Microsystems May 1981), this is the first time that Instant Speech has been available at the one-off component level. The new TDS934 chip set comprises a speech synthesizer (TDSg0) and speech memory (TDS92-001) and four normal ICs which provide voltage regulation and analogue filtering. Together with resistors, etc, found in the general-purpose laboratory, the purchaser has all the components needed to build his own system. (At £39, it forms a low cost basis for an expandible system.)

Sixteen utterances No microprocessor drive is needed (although it interfaces easily in serial or parallel if required). Simple switch closures select up to 16 different utterances. The Speech Memory supplied with the TDS934 chip set has the digits 0 to 9 as well as other useful words. The Instant Speech service offered by Triangle provides analysis of the users own vocabulary. High quality synthetic speech retaining the emphasis of messages in any language can be delivered in TDS292 speech memories with 48 hours. (Triangle Digital

Services Ltd, 23 Campus Road, London EI7 8PG, UK. Tel: 01-520 0442)

Instant Speech off the shelf 487