30-pin SIMM Memory Tester

Introduction

I purchased big lot of memory sticks many years ago. Among them is about 30 30-pin SIMM memories. I've modified a ZRC to test these memories.

Engineering Changes

Two SIMM30 sockets are ganged together:

SIMM pins	Signal Names	ZRC Signals
1	5V	T2
2	nCAS	T5
3	D0	RC2014-27
4	MA0	T11
5	MA1	T12
6	D1	RC2014-28
7	MA2	T13
8	MA3	T14
9	GND	T3
10	D2	RC2014-29
11	MA4	T15
12	MA5	T16
13	D3	RC2014-30
14	MA6	T17
15	MA7	T18
16	D4	RC2014-31
17	MA8	T19
18	MA9	T20
19	MA10	T21
20	D5	RC2014-32
21	nWE	R8-2
22	GND	T3
23	D6	RC2014-33
24	MA11	NC
25	D7	RC2014-34
26		NC
27	nRAS	T4
28	Parity RAS	4.7K pull up
29		NC
30	5V	T2

CPLD Modifications

Since ZRC already has a 2megx8 DRAM, the mulitplexed addresses for DRAM are duplicated to drive T11-T21 (MA0-MA10). The RAS, CAS, and WE to DRAM are also duplicated in T4, T5, R8-2, respectively. The control lines to onboard 2megx8 DRAM is negated, so ZRC runs from the SIMM30 memory.

CPLD design files

Retro PCBs Wiki

Table of Contents

Table of Contents

30-pin SIMM Memory Tester

Introduction

Engineering Changes

CPLD Modifications