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RAM Chips in some of your favorite vintage computers!


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After stocking my Atari800XL with new RAM that I had for my C64, I went on a search for some cross-references to find out what other IC's would work as a drop in replacement. I've used several of these types in various C64's (NOT the C64C) with complete success. If you find any errors or additions, please let me know!

 

The 4164 RAM IC has been shown to work in the following computers -

 

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Apple IIe

Apple IIc (Early - Mid production) — late models with 4464 chips, do not work with 4164's
Apple Macintosh 128k

Atari800XL

C64 - (Early - Mid production) — late models with 4464 chips, do not work with 4164's (C64C)
C128 - (Early - Mid production) — late models with 4464 chips, do not work with 4164's
C PET (Replaces 4116's) - See note at bottom for modification?
COCO 2 - (Early - Mid production) — late models with 4464 chips, do not work with 4164's

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4164 64K x 1 DRAM Cross Reference:

Fairchild - MB8264-15

Hitachi - HYB4164P2BD, HM4864

Micron - MT4264-25

Mitsubishi - M5K4164AP-15, M5K4164 ANP-10

Mostek - MK4564N-20

Motorola - MCM4164BP15, MCM6665BP20, MCM6665AP

NEC - D4164C-2, D4164C-15, uPD 4164-1

Samsung - KM4164B-15

OKI - M3764A-15

Toshiba - TMS4164-15NL, TMS4164-20NL

 

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I also found some information on replacing 4116 RAM with 4164/4516 RAM. Here is the info from the C64 Wiki about replacing 4116 RAM with 4164 RAM (I'm not sure if the method is the same for the 4516 RAM):
Some of the systems that use 4116 RAM are the Colecovision consoles, TI 99/4A computers, and some Williams arcade PCB's like - Defender, Joust, Robotron.

How to use a 4164 chip instead the original 4116:

  • Bend pin 1 und 8 upwards so they no longer go into the socket's connectors.
  • Connect Pin 8 and 9 with one another through a short piece of wire.
  • Make sure pin 1 and 8 are not in contact with any other components nearby.
  • Insert the chip like this into the socket.

If you need one of the 4164 chips, you can also use a 41256 instead. You have to solder a short piece of wire between pins 1 and 16 of that chip (these are the pins just left and right of the alignment notch on the chip). This mod will make the chip look just like a '64 chip to the system.

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PLEASE make sure to check my notes before you purchase or install these RAM IC's. It's always good to make double - sure!

I hope this list helps you find the RAM that you need!

Edited by TheRealAnubis
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They're also used in early XE models, later models and XEGS use 4-bit RAM ICs.

 

So long as access time is under about 250 ns 4164 RAM should be good for Atari. C64 requires slightly quicker time.

By the time these ICs were in use, 150 ns or better was a common speed.

 

A common upgrade was to replace 64k with 256k chips and connect the additional address pin, also requires extra external logic.

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