Re: Faster IEEE routines

From: Mike Naberezny <>
Date: Wed, 24 May 2017 12:07:21 -0700
Message-ID: <>
On 5/24/17 9:52 AM, Jim Brain wrote:
> Write your own parallel routines using the IEEE lines as conduits for your non 
> IEEE protocol.

I suggest that any new protocol using the IEEE-488 lines should be designed to 
be compatible with the 75160/75161 transceivers.  This will allow it to be 
used on the CBM-II computers and also the modern PetSD-based devices.

On the PET/CBM computers, the IEEE-488 lines use MC3446 transceivers.  The 
lines can be controlled independently and used in nonstandard ways.  I believe 
this is true of the drives also, but I haven't checked all of them.  The 
CBM-II computers use the 75160/75161.  They are more restrictive.

The SSE SoftBox is a peripheral designed for PET/CBM only.  It uses the 
IEEE-488 data lines in an interesting way.  It has a mode where six of the 
eight data lines are used as outputs while the remaining two are used as 
inputs.  When I ported the code to CBM-II, I found that the CBM-II hardware 
wasn't capable of doing this because of the different transceivers.


Mike Naberezny (

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Received on 2017-05-24 20:00:02

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