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Tms9900 based moog: the SL8

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"One of the really cool attributes of the TMS 9900 MCU was it had a considerably faster 3.3 MHz clock than the 8051/8031 MCU used in the Roland and the 8085 in the Korg units at the time. It ran rings around a Z80 because of the 16 bit data path and the unique ability of the 9900 to store all user registers in RAM and update the "RAM Registers" in a single instruction cycle. If you called a subroutine or a NMI call was true, you could update the user register directly. This was how all of the parameters were stored/updated once a program or configuration change was made. It also made complex multi tasked threading for the housekeeping, DCO timing, triggering, MIDI, and controller interaction much simpler to code.



Edited by Elia Spallanzani fdt
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Which brings me to the question - did the author actually measure this performance bonus of the 9900, or just believe it?

Comparing clocks between different architectures does not make sense, and our glorious 16-bit data path brought us read-before-write.

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