RAM 16A Rev-1
RAM 16A
The IMSAI RAM 16A is a 16KB static RAM board for the S-100 bus.
It may be configured by DIP switches to be either IEEE 696 or IMSAI compliant.
It is designed around the popular 2114 1K×4 chips.
These chips have four times the density of the original 8111 and 2102 chips used in previous static RAM boards.
The RAM 16A replaces the discontinued RAM 4, RAM 4A, and RAM-16 boards.
It has four times the memory of the RAM 4A and less than half the access time.
Like the RAM 4A, the board has green LEDs that indicate when the board is being accessed down to the 1K chip level.
The board is organized as sixteen blocks of 1K and may be addressed starting on any of four 16K boundaries.
Each block may be separately enabled or disabled to avoid any address conflicts with existing memory mapped boards.
The RAM 16A supports extended addressing and may be configured for IEEE 696 or IMSAI compliant via DIP switches.
Extended address decoding may be disabled by a DIP switch.
The RAM 16A implements memory overlays with the PHANTOM signal to disable otherwise addressable memory.
It may be configured by DIP switches to be either IEEE 696 or IMSAI compliant.
The address decoding and signal buffering has been carefully designed for the highest possible speed.
IMSAI recognizes that machines being built today may operate at a much higher speed than was originally envisioned for the S-100 bus.
The RAM chips in this kit have an access time of 150 nanoseconds.
With the additional address and data buffering, the access time is 200 nanoseconds.
If this speed does not meet the needs of your system, you may select a wait state for all memory cycles.
The RAM 16A does not depend on the MWRT bus signal (pin 68) for normal operation where optimal write cycle timing is derived directly from the S-100 bus pWR* and sOUT bus signals.
If the front panel stops the system, memory writes are driven by the MWRT bus signal which implement the front panel’s DEPOSIT and DEPOSIT NEXT functions.
Complete Kits
Order one from the list below. The kits are complete with everything you need except solder and tools unless otherwise stated.
They even come with a professionally printed user manual.
Be sure to hover over any  icons for more information.
Most builders won’t need anything else besides one of the above complete kits.
To skip over the options go to More Information to get links to useful resources.
If you're an advanced builder and want to see all the options, read on.
Bare Board
You may order a bare printed circuit board for you to use your own parts.
Be advised that individual parts are not available to bare board customers unless they are explicitly in the parts list below.
IMSAI Parts
Generic Parts
Component Sourcing Statement
All components in the RAM 16A Rev-1 kit are new production with the exception of the 2114L-15 ICs which are new old stock.
Links
IC Datasheets
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