[rescue] Some days ....

Dave McGuire mcguire at neurotica.com
Sun Jun 8 15:37:50 CDT 2003

On Sunday, June 8, 2003, at 04:16 PM, Curtis H. Wilbar Jr. wrote:
>> The original PC has more than enough IRQs and DMA channels for a cheap
>> and nasty home PC ... that's all it was supposed to be. If IBM thought
>> they were designing the future of PC's for the next zillion years they
>> would have been a little more thoughtful; it would probably have been
>> something like the 360 and cost so much that very few would have sold.
> That's fine for the PC... but the AT when it came out (where they did
> that whole two 8 IRQ thingie) was meant to be more serious... it would
> have been better if they adopted a higher capacity IRQ system...  I
> don't even know if in an original AT you populated every slot with a
> card requiring an IRQ that there would have been enough... never mind
> today's boards with all their integrated peripherals...

   It would have been enough.  The original AT had 8 slots if memory 
serves, and there were 15 IRQs available (also if memory serves).

   Keep in mind, though, that their primary limitation in designing the 
AT was to maintain full hardware and software compatibility with the PC 
and XT.  The biggest reason why PC architecture is so fucked up, even 
today, is due to design flaws and limitations in the very first PC 
design and the perceived need for full backward compatibility.


Dave McGuire             "I've grown hair again, just
St. Petersburg, FL           for the occasion."       -Doc Shipley

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