[Coco] 6309/6809 opcodes with mixed 8/16 bit registers

[jdaggett at gate.net]

On 22 Nov 2012 at 11:31, Luis Antoniosi wrote:

> 
> in theory a Core-Memory computer could literally catch fire if the
> processor is halted reading the same address...
> 
> but this must be another urban legend...  :P

Actually the term Halt and Catch Fire is a misidentification. It was the first attempt to put 
some sort of test routine within the processor to aid testing the address bus. 

Later processors that included internal RAM and a boot ROM code like the HC11's allowed 
one to download small test programs into RAM and exercise the ports and functionality of the 
processor before shipping. This was often done at die probe and after packaging. Back then 
ceramic packaging was very expensive. Even Injection molded plastic was not real cheap. 
The plastic package was around $0.10 per pin then. So 40pins was $4. You don't make a lot 
of profit if you put to many bad die into $4 packages.

In 2000, when I worked in Paging Products we were using an HC11PH8 in an 80pin BGA 
package. The packaged part was costing us nearly $7 at a run rate of 1 million per year. 
About 40% of that cost was packaging if I remember correctly.

james