Genicom 3600 manual Memory, Static RAM, RAM Access Time, Eprom Access Time

Appendix A

Memory

The MC68332 has separate address busses and data busses. All I/O is memory mapped and the SIM chip selects are used to select program space, data space, and I/O.

Static RAM

The 3600 comes with 128K of battery backed static RAM. The RAM is configured as 128Kx8. The chip select for accessing SRAM should be configured to at least one wait state. The RAM can also be upgraded to

512K x 8 by swapping the component at location U6. The jumper between pins 1 and 2 of J3 must be removed and placed across pins 2 and 3.

RAM Access Time

Processor access time >= RAM access time

3 x CLK >= Tcslow + Tramaccess + Tsetup + Thc32

3 x 1/16 MHz >= 30 ns + 120 ns + 5 ns + 18 ns

187.5 ns >=173 ns

EPROM

The EPROM for the 3600 consists of two 512K x 8 EPROMs configured as 512K x 16, giving a total of 1M of EPROM space. The EPROMs have an access time of 150 ns and do not require wait states.

EPROM Access Time

Processor access time >= EPROM access time

2 x CLK >= Tcslow + Tepromaccess + Tsetup

2 x 1/16 MHz >= 30 ns + 70 ns +5 ns

125 ns >= 105 ns

DRAM

The main memory consists of 256K of dynamic RAM. The DRAM is configured as 256K x 16, IC U26. To support the DRAM interface, GAL U13 is used to handle refresh and control lines between the DRAM and the processor. See Part II, Appendix A for GAL listings of the current configuration. Multiplexors U16, U18, and U20 are used to generate the row and column addresses for the DRAM.

A-9