garlick@ecst.csuchico.edu (Jim Garlick) (01/14/91)
I have come across a mystery piece of equipment manufactured by "Acc", circa 1980, that looks like some kind of sophisticated modem. It is a box with four plug-in modules: two "power modules" and two "logic modules". Front panel says "ECU". Lots of led's and toggle switches, plug out the back that says "to host/imp" and "comm line". A big piece of packing tape on the top says "Arpa". Anyone know what this is or how to get ahold of Acc? Jim Garlick garlick@ecst.csuchico.edu Jim Garlick System Software Specialist garlick@ecst.csuchico.edu (916) 898-4635
stjohns@UMD5.UMD.EDU ("Mike StJohns") (01/14/91)
>> >> I have come across a mystery piece of equipment manufactured by >> "Acc", circa 1980, that looks like some kind of sophisticated modem. >> It is a box with four plug-in modules: two "power modules" and two >> "logic modules". Front panel says "ECU". Lots of led's and toggle >> switches, plug out the back that says "to host/imp" and "comm line". >> A big piece of packing tape on the top says "Arpa". >> >> Anyone know what this is or how to get ahold of Acc? Jim, the box you have is an "Error Correcting Unit" one of the last of a dying breed - donate it to your museum. ECU's were used in the old ARPANET and are still used in the MILNET to take an 1822Distant Host interface and extend it over a standard bit-synchronous data stream. The ECU's converted the 1822 control and data signals into an SDLC (I think?) stream. ACC is still on the net - you might check with Gary Krall (krall@acc.com) Mike
rcoltun@NI.UMD.EDU (Rob Coltun) (01/14/91)
Ahh. An error correction unit (ECU). Lets see, it was used to insure reliability between two endpoints of a 50kb analog (line between 316/516 IMPs or maybe between an IMP and a VDH) or something like that. It's been a long time, it's a bit fuzzy. ---rob
enger@SEKA.SCC.COM (Robert M. Enger) (01/14/91)
Rob: Works on DDS circuits too! You and I were on were on the opposite ends of one, in the now distant past :-) Bob
hsw@SPARTA.COM (Howard Weiss) (01/14/91)
The ECU was an Error Control Unit that allowed hosts to be separated from their respective IMPs (now packet switch nodes) on the ARPANET/MILNET. Using the distant host interface, the host to packet switch interface could only drive a signal about 2000 feet (which was a great improvement over the 30 feet that was achievable with local host interfaces). The ECU allowed a host to be separated by a larger distance and still look like it was a locally attached host. Basically, the ECU converted the ARPANET 1822 interface signalling into an SDLC which was then recoverted into 1822 by the distant end ECU. ECU's were always used as pairs - one on the host end and one on the IMP end. ACC at the time was Associated Computer Consultants and they are now known as Advanced Computer Communications. Sorry, don't have a phone number. Howard Weiss SPARTA, Inc. Columbia, MD 21046 hsw@sparta.com