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Re: [N8VEM-S100:5290] Re: Ithaca Intersystems DPS-1 Front Panel

I will try to do this tomorrow. One of my systems came from a doctor's office, I bought it from the doctor. It was in daily use generating his billing, back then. I did the usual capacitor change and contact cleaning, and she has been running ever since. This is one of the machines that has no diode pack.


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On Sep 18, 2014, at 10:18 PM, Steven Feinsmith <steven.f...@gmail.com> wrote:


Can you kind to measure your DSP-1 front panel board in length for me then I will get prototype board at correct length. Also check with height too.

I also received email message from my old friend in California and he checked his DSP-1 and said he did not have "Diode Pack" installed. It is possible that part was an optional item.

I will build the prototype without "Diode Pack" and then add it later to compare bus signals.


On Saturday, September 13, 2014 3:00:10 PM UTC-4, Steven Feinsmith wrote:
Hi everyone,

I have very little documentation for Ithaca Intersystems DPS-1 system. This device was last manufactured before S-100 become obsolete due to Apple and IBM hit the market in 1980's. The front panel for DPS-1 system was one of the best designed. Nowdays, there were impossible to find it. I reviewed components that used for the front panel were available from varies sources.

But one component, IC7 as labelled as "Diode Pack". I realized there was no information about it. I looked the schematic showed  "HEADER" contained D0-D7 (Data Bus) to AM25LS2521PC, Eight Bit Equal To Comparator (AM = Advanced Micro Devices) connected for Data Breakpoint (Low) and Breakpoint Enable (Low). Other side connected to front panel DATA switches. Between "Header" and AM25LS2521PC, there are "Diode Pack" as IC7. The "Diode Pack" hook up with D0-D7 bus, +5 volt and ground. That is all what the schematic showed.

What do you think about inside the "Diode Pack". Perhaps array of diodes? Perhaps pull-up or pull-down resistors?

I enclosed a manual, "A FRONT PANEL FOR THE S-100 BUS" by Ithaca InterSystems, Inc, 1979. The company languished in the 1980's, not being part of the domination of the IBM PC and PC clones. The company was dead for more than 30 years ago. Hopefully, you have skill to find out what is inside of the diode pack.

It would be nice for N8VEM group to create clone version of this wonderful front panel. By the way, you know about "Header" is capable to run 16-bit system by add 8 data buses, more data switches and more data LEDs. IT may sounds like a big challenge for us to create new generation of front panel board. Good idea?

Thank you,

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