February 12, 2020
The Signetics N8x300
This is a peculiar 1980's era microcontroller manufactured by Signetics (Philips).
It had 16 bit instructions, a 16 bit path to instruction memory, an 8 bit ALU and
registers, and no provision for access to RAM. Some people call it the first DSP.
I have run across it in obsolete hard drive controllers. Apparently it had military
applications and was copied by the Russians.
Learning Assembly Language
The 8x300 is an odd choice for a first processor to learn assembly language on,
but why not?
8x305
I have seen this chip substituted for the 8x300 on some boards. This is an improved chip with 13 registers
instead of 8. It could also run at 10 Mhz rather than 8 Mhz. It was pin compatible and could run 8x300
code just fine, so if availability dictated, it could be purchased and substituted in lieu of the 8x300.
8x3xx family chips
- 8x320 - bidirection ram bus interface
- 8x330 - floppy controller
- 8x36 - 8 bit IO port (sometimes marked 8x376)
Devices based on the 8x300
The Olivetti M20 disk controller used the 8x300, and a manual can be found if you scrounge around.
Feedback? Questions?
Drop me a line!
Tom's Computer Info / tom@mmto.org