Hello,

 This is a tested and working project.

This A500 2MB Trapdoor memory Expansion is an Easy DIY project, all components are through hole, marked on the PCB, Easy to solder, Easy to make ;)

This Amiga 500 2 Mega Bytes RAM (Random Access Memory) expansion card PCB is designed for Amiga 500 Rev.5 and Rev.6 boards Trapdoor Expansion.

This Amiga 500 2MB memory expansion PCB must be connected to a special GARY ADAPTER circuit for proper operation.

https://www.pcbway.com/project/shareproject/AMIGA_500_2MB_RAM_EXPANSION_GARY_ADAPTER.html

 Components:

74F139 (DIP16)

16pcs. 256K x 4Bit dynamic DIP20 RAMs

16pcs. DIP20 IC sockets (some chips may be defective, sockets make easy to repace them)

13pcs. 68 ohm 1/4 wattt resistances (R1-R13)

2pcs. 10K ohm 1/4 wattt resistances

16pcs. 330nf 50V 5.08mm pitch (0.2inch pitch) ceramic capacitors (C1-C16)

1 piece 2x28 pin female header. (get 2x40 pin female header then cut it)

3pin 2.54 pitch male header

1 piece 3pin 2.54mm SPDT slide SWITCH

Some of compatible 256K x 4Bit dynamic RAMs list: (You can find from Aliexpress)

TMS44C256 (Texas Instruments)

MB81C4256 (Fujitsu)

GM71C4256 (Goldstar)

HM514256 (Hitachi)

HY534256 (Hyundai)

MT4C4256 (Micron)

M5M44256 (Mitsubishi)

MCM514256 (Motorola)

MSM514256 (Oki)

KM44C256 (Samsung)

TC514256 (Toshiba)

LC324256 (SANYO)

UPD424256 (NEC)

In order to protect your electronical devices, always turn off your Amiga before connecting or unconnecting any device.

Gerber files can be changed at any time. Before paying for the PCBs, be sure to update your orders!

Have fun

Thank you