13 May
2005
13 May
'05
9:11 p.m.
Subject: Re: Anyone playing with the 8x300
From: "Dwight K. Elvey" <dwight.elvey at amd.com>
Date: Fri, 13 May 2005 14:57:09 -0700 (PDT)
To: cctalk at classiccmp.org
It's more of a sequencer or state machine with a crude ALU.
As to those 8 instructions, looks at what the fields are
for each one. I've done horizontal microcode and that is
similar. Due to it's very harvard design it's not one you
will do constans in rom much. Also the IO devices are
really IO specific as in the address of each is coded
into the part.
One use for it was an 8bit wide DSP. I have a real one here
of the later 8x305 I2L that was a bit faster.
Allison
Ah the classic first of the fast microcontrollers.
I'd have to dig but I vaguely remember the 8x300
as a disk controller apnote. Nasty beast to program.
Allison
Hi
Don't know why you'd say this, it only has 8 instructions!
I've got the spec posted to Al's site.
This controller application is a little interesting in that
who ever designed this board, also must have done a bitslice
designs at one time or another. To save a machine cycle, all
I/O addresses are selected by a ROM tied to the instruction
addressing. Normally it would take two cycles, one to write
the I/O address and one to transfer the data. With the
ROM, the address is understood by the program's execution
address location.
Dwight