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Re: Ithaca Intersystems DPS-1 Front Panel

Thank you for a quick responded and I did look TID126 datasheet and then compare between IC7 for front panel against the datasheet. I realized they were not same and they were not compatible. Perhaps you may correct this diode array was possible that Ithaca InterSystems engineer designed for the DSP-1 board.

I tried to blow up the pix from internet website to see component labeled. Unfortunately, they were blurred and no way to read the label. I do not know if anyone may own DSP-1 based computer system and then can look IC7 and find what this chip labeled would be much help.

What I can find from schematic for IC7 connected as follows:

1      +5
2      D1
3      D2
4      NC
5      D4
6      NC
7      D6
8      D0
9      D5
10    NC
11    D3
12    NC
13    NC
14    Ground

Meanwhile, it may take tremendous time to search anf find correct component for IC7. I will try to use 16 pieces of diodes and see if it will work as much as like the original ones.

Thank you,


On Saturday, September 13, 2014 3:48:41 PM UTC-4, yoda wrote:
If you use google and look for tid126 you will find the data sheet - could easily replicate this manually - they are also available on eBay as well.  If doing a new board would be cheaper to use 16 diodes as the data sheet shows  - I think they are just for signal protection.

On Saturday, September 13, 2014 2:00:10 PM UTC-5, 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,