Anyone playing with the 8x300

[Allison]

>
>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
>
>>
>>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

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