RAM 4 (Discontinued)

IMSAI RAM 4-4  
                 
 

The IMSAI RAM 4 board provides up to 4K bytes of static random access memory. Designed to utilize the Intel 2111 or 8111 chips, the RAM-4 board can be flexibly configured to contain up to 4K bytes in 256 byte increments. The board address can be switch-or jumper-selected to any 4K block of the computer's 64K memory space. Tri-state bus drivers and a fully-decoupled on-card voltage regulator provide plug-in compatibility with either the IMSAI 8080 or the Altair computer systems.

The RAM-4 also features write-protect, a capability useful in the development and debugging of programs. Four separate write-protect switches are provided on the RAM-4 board, each controlling a separate 1K of memory.

The RAM 4 comes in two configurations.

• The RAM 4-4 provides the full 4K of RAM.
• The RAM 4-1 contains 1K of RAM. The board may be fully populated in 1K increments, up to 4K bytes by adding M11-1 sets.
• The M11-1 is used to add storage capacity to the RAM 4-1 board.

Current Status

The RAM 4 board is no longer in production. It was retired in 1975 when the RAM 4A was released.

Successors

The RAM 4 was succeeded by the RAM 4A, which was succeeded by the RAM 16A in 2025.

Resources

Manual

• RAM 4 Rev-1 User Manual

Schematics

• RAM 4 Rev-1 Schematic

Spare Parts

While most of the parts on the RAM 4 are generic and commonly available (except the 8111/2111 RAMs), these parts may be somewhat difficult to source.