Anyone playing with the 8x300

[Dwight K. Elvey]

>From: "Allison" <ajp166 at bellatlantic.net>
>
>>
>>Subject: Anyone playing with the 8x300
>>   From: "Dwight K. Elvey" <dwight.elvey at AMD.com>
>>   Date: Fri, 13 May 2005 14:29:31 -0700 (PDT)
>>     To: cctalk at classiccmp.org
>>
>>Hi
>> I'm looking at an application of the 8X300 by
>>Signetics. This is for a hard disk controller.
>>Is anyone fiddling with simmulators for this processor.
>>It seems like someone was a while back.
>> My current application is on an Olivetti M20 not
>>a TRS80.
>>Dwight
>>
>
>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