Out in Front: March 1, 1996
The Am186ES/Am188ES from Advanced Micro Devices (AMD) maintains software and feature compatibility with the long-lived 80C186/188 but delivers higher performance and greater functionality than the older devices. The company based the processors on a 20-MHz 80C186 core, which will eventually reach 40 MHz. The core requires a 20-MHz crystal (1×) and uses an internal PLL to double the duty cycle. On standard 186s, the crystal must be twice the core operating frequency.
In addition to the 186's standard features, the ES devices have two asynchronous serial ports that perform 7-, 8-, and 9-bit data transfers with full-duplex operation. AMD designers have enhanced the DMA controller to allow you to perform DMA transfers to and from these serial ports. The watchdog timer, adjustable down to microsecond granularity, is programmable to generate a nonmaskable interrupt (NMI) or a reset. If you program the watchdog to generate an NMI and your system can't find the NMI routine, the watchdog performs a reset.
AMD designers added a simple pulse-width demodulator, two additional external interrupts that are multiplexed with internal DMA interrupts, and an asynchronous interface that allows you to attach 68K-style peripherals, as well as the standard x86 peripherals. The ES devices have a glueless interface to ROM, SRAM, pseudo-SRAM (PSRAM), and flash. Because of the 186's 1-Mbyte address-range limitation, PSRAM is more appropriate than DRAM because of the PSRAM's smaller granularity.
The ES devices also have 32 programmable I/Os with integrated pullups or pulldowns and are multiplexed with other functions to save pins. On the 186ES, the bus width for the upper-chip-select region is always 16 bits, forcing you to use 16-bit memory for boot code. However, you can configure the lower-chip-select memory region independently as 8 or 16 bits. Unlike the standard 186/188, both the 186ES and 188ES have nonmultiplexed address/data buses. The 186ES and the 188ES, available in 100-pin TQFPs and PQFPs cost $8.80 and $8.50 (10,000), respectively.
—by Markus Levy
Advanced Micro Devices, Austin, TX. (512) 462-4360.