DRAMS

DRAMS

Dynamic Random Access Memories used in ZX Spectrum machines.

4116

16Kx1 bit DRAM chip

8 of this IC make the lower 16k part of the ZX Spectrum 16K/48K RAM.

e.g. NEC D416C-2

Pinout:

(-5V) VEE DIN WE RAS A0 A2 A1 (+12V) VDD

1 °     16 2       15 3       14 4       13 5       12 6       11 7       10 8        9

GND (0V) CAS DOUT A6 A3 A4 A5 VCC (+5V)

4532

32Kx1 bit DRAM chip

The addressing logic uses 8 line (A₀ to A₇) for row address (RAS) and 7 line (A₀ to A₆) for column address (CAS). At CAS the A₇ line has to be fixed at logic 0 or 1 depending on chip type.

8 of this IC make the upper 32k part of the ZX Spectrum 48K RAM.

e.g: TI TMS4532-20NL3 or OKI M3732-L TI TMS4532-20NL4 or OKI M3732-H

Pinout:

NC DIN WE RAS A0 A2 A1 (+5V) VCC

1 °     16 2       15 3       14 4       13 5       12 6       11 7       10 8        9

GND (0V) CAS DOUT A6 A3 A4 A5 A7

A₇ should set logical 0 at CAS for TI TMS4532-20NL3 and OKI M3732-L chips, and logical 1 for TI TMS4532-20NL4 and OKI M3732-H chips.

The A₇ line is omitted for refresh address.

4164

64Kx1 bit DRAM chip

16 of this IC make the 128K RAM of the ZX Spectrum 128K and ZX Spectrum +2 (except ZX Spectrum +2A/2B).

e.g:NEC D4164C-3

Pinout:

NC DIN WE RAS A0 A2 A1 (+5V) VCC

1 °     16 2       15 3       14 4       13 5       12 6       11 7       10 8        9

GND (0V) CAS DOUT A6 A3 A4 A5 A7

4464

64Kx4 bit DRAM chip

4 of this IC make the 128K RAM of the ZX Spectrum +2A/2B, +3/3B.

e.g:MICRON MT4067-15

Pinout:

OE DQ1 DQ2 WE RAS A6 A5 A4 (+5V) VCC

1 °     18 2       17 3       16 4       15 5       14 6       13 7       12 8       11 9       10

GND (0V) DQ4 CAS DQ3 A0 A1 A2 A3 A7