Schematics and description of an acoustic memory (1k byte, Display terminal, 1969)

Eric Smith eric at brouhaha.com
Sun Apr 13 04:36:22 CDT 2008


Jean-Marie Pichot wrote:
> This display terminal was designed in 1969,  [...]  Remember,
> in that time, there are no micro-processor, neither RAM chips!

There were RAM chips in 1969.  Most of them stored 16 bits or
less.  I have not been able to determine when the first 64-bit RAM
appeared, but it might have occurred by then.

Examples of RAM chips available in 1969 were the Fairchild U6A903059X
8-bit RAM and U6A903359X 16-bit RAM.  The base part numbers were 9030
and 9033, respectively.  These were part of the CTuL Complementary
Transistor Logic (CTuL or CTL) family.  Don't get confused by that
name; these were complementary *bipolar* transistors, not CMOS.  Many
years later Fairchild reused the CTL abbreviation for something entirely
different, Current Transistor Logic.

By the time of the 1972 Fairchild TTL Data Book, the 9033 designation
was changed to 93433.

The 9030 was used in the KM10 fast memory "option" for the DEC KA10, the
first PDP-10 processor, designed in 1967.

For a raster display terminal in 1969, delay line memory was obviously
more practical than semiconductor memory, since the density of available
RAM chips was too low.  This started to change in 1970 when Intel
introduced the 1101 static RAM (256 bit) and the 1103 dynamic RAM
(1024 bit), though there were initially a lot of reliability problems
with the latter.

The next generation of raster display terminals used MOS dynamic
shift register memory, which was less expensive than RAM.  As far
as I'm aware, not many display terminal designs used RAM chips before
1977, and MOS shift registers were still being sold into the mid 1980s.

Eric




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