That darn Intel jingle...

Allison ajp166 at
Thu Nov 3 19:01:38 CST 2005

>Subject: Re: That darn Intel jingle...
>   From: "Chuck Guzis" <cclist at>
>   Date: Thu, 03 Nov 2005 16:17:54 -0800
>     To: cctalk at
>On 11/3/2005 at 6:45 PM Allison wrote:
>>Z80 PIO.
>16 measily bits of I/O in a 40 pin package. :(  What a waste of real

But long lived.

>>D72055 the last version of the part hit 12mhz.  If your going on PCI 
>>why bother and just put a gate array to work
>Mostly laziness.  I could probably also just buy a PCI data acquisition
>board, if I didn't want Mode 2 I/O (which I do).

I used 8155s but then again I also use 8085s which work nicely with it.

>>Well there are plenty of 8251, 8253, 8259 around, then there are the 2681s
>>and (gag) 8250 series. 
>Well, the 8259's a CPU support chip, and I tend to think of the
>8253/54/57/37 the same way.  

the 53 (timer),54(Timer), 57(DMA) and 37(better DMA) are not strongly
related to any specific CPU and work fine with Z80, 808x even 8048.  

>The 51's a peripheral chip that's had its share of warts, however. 

8251 is wartly enough but ok.  The Leading Edge  Model D XT clone used 
it rather than the icky 8250.

> The 8250 is a ridiculous National product that
>can't do sync in a single-channel 40 pin package yet.  The Z80 SIO and the
>Intel 8274 are essentially the same chip that should have probably been
>made part of the PC instead of the 8250.

8274 is the intel branded NEC D7201, and it's not essentually a Z80 sio
it's IS a SIO save for it supports 8080/8085/8088 interrutpts instead.
Even the register addresses and functions are the same save those for
the interrupts.

>Speaking of which--I've got a bunch of Z80 DART chips.  I've been told that
>these are really derated Z80 SIO chips.  Will they do synchronous I/O or
>has that part been disabled?  I can't find my databook for the things any
DART is Async only, still a good part.


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