
40
Evaluating and Programming the 29K RISC Family
MHz and the DRAM operates with 4–cycle initial access and 2–cycle subsequent
burst accesses. So, although the performance is good, it is not as high as other mem-
bers of the 29K family.
The SA29200 board measures about 3 by 3.5 inches (9x10 cm) and has connec-
tions along both sides which enable attachment to an optional hardware prototyping
board (see following section). This extension board has additional I/O interface de-
vices and a small wire–wrap area for inclusion of application specific hardware.
1.8.11 The Prototype Board
The prototying board is inexpensive because it contains mainly sockets, which
can support additional memory devices, and a predrilled wire–wrap area. The RISC
microcontroller signals are made available on the prototyping board pins. Some of
these signals are routed to the empty memory sockets so as to enable simple memory
expansions for 8–bit, 16–bit or 32–bit EPROM or SRAM. There is also space for up
to 16M bytes of 32–bit DRAM.
Using the wire–wrap area the microcontroller I/O signals can be connected to
devices supporting specific application tasks, such as A/D conversion or peripheral
control. This makes the board ideal for a student project. Additionally, the access
times for memory devices are programmable, thus enabling the effects of memory
performance on overall system operation to be evaluated.
1.8.12 Am29200 Evaluation
The Combination of the GNU tool chain and the low cost SA29200 evaluation
board and associated prototping board, makes available an evaluation environment
for the industry’s leading embedded RISC. The cost of getting started with embedded
RISC is very low and additional high performance products can be selectively pur-
chased from specialized tool builders. The evaluation package should be of particu-
lar interest to university undergraduate and post–graduate courses studying RISC.
1.8.13 The Am29205 Microcontroller
The Am29205 is a microcontroller member of the 29K family (see Table 1-3). It
is functionally very similar to the Am29200 microcontroller. It differs as a result of
reduced system interface specifications. This reduction enables a lower device pin–
count and packaging cost. The Am29205 is available in a 100–lead Plastic Quad Flat
Pack (PQFP) package. It is suitable for use in price sensitive systems which can oper-
ate with the somewhat reduced on–chip support circuitry.
The reduction in pin count results in a 16–bit data/instruction bus. The processor
generates two consecutive memory requests to access instructions and data larger
than 16–bits. The memory system interface has also been simplified in other ways.
Only 16–bit transfers to memory are provided for; no 8–bit ROM banks are sup-