Interesting old circuit board -- Any ideas? - Page 1
Forum section: electronics / general

author: Unknown
author_rank: Unknown
timestamp: February 03, 2014, 08:19:19 am
content: Hi everyone,I thought I'd share this with you all as I found it rather interesting; a circuit board from the mid 1980's manufactured by 'Sitec Corporation Pty. Ltd.' right here in Sydney, Australia. I've found no information about this board or the company itself.What's immediately noticeable about this board (apart from the huge 10,000uF cap) are the five 25-pin interfaces along one side. Also featured is an Intel 8085 microprocessor (at a whopping 5MHz clock), an Intel P8273-4 chip (no idea what this is) and five EPROMs (I think I can make out HN482732AG-30 under one of the labels).I have no idea what this board does or what it's part of. Perhaps someone on here could impart their knowledge or maybe point out some other interesting aspects that you can see. Photos are attached (apologies for the low resolution; file size limits).- Michael

author: GeoffS
author_rank: Unknown
timestamp: February 03, 2014, 08:26:49 am
content: Scitec manufactured communications equipment.Those 25 pin connectors are probably RS232.

author: andtfoot
author_rank: Unknown
timestamp: February 03, 2014, 08:41:11 am
content: Quote from: GeoffS on February 03, 2014, 08:26:49 am+1, based on the chips used:http://www.onsemi.com/pub_link/Collateral/MC1489-D.PDFhttp://www.ti.com/lit/ds/symlink/sn55188.pdfBased on an old eBay listing, it is a 'data concentrator'.

author: wiss
author_rank: Frequent Contributor
timestamp: February 03, 2014, 08:49:18 am
content: The structure is somewhat similar to a pdp11 terminal interface card (the one I have has some 12 Dsub25`s, I think).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 03, 2014, 08:54:42 am
content: The INS2651s are programmable USARTs, much like the hardware in an average MCU (and more generic than an 8250/16550 SIO). These interface via SN75188 RS-232 line drivers and MC1489 receivers.The signaling is definitely RS-232, but that other DIP40 is a HDLC/SDLC controller:http://datasheet.elcodis.com/pdf2/75/73/757320/p8273.pdfAs for what the software is doing, you'd have to debug the ROMs and figure it out for yourself. Seems like communication routing, packet switching, passing messages from here to there. Definitely not enough power or memory to do any real processing on the ports, nor an output for data logging purposes or whatever.As for the 10mF cap, with all the roasty-toasty old NMOS chips on there, that board alone will consume about two amperes at 5V. 'Twas the days before CMOS VLSI, and boards were hungry!Tim

author: electronics man
author_rank: Frequent Contributor
timestamp: February 03, 2014, 06:17:42 pm
content: Where did you get it? And I love the mod wires

author: Unknown
author_rank: Unknown
timestamp: February 03, 2014, 06:33:42 pm
content: Quote from: electronics man on February 03, 2014, 06:17:42 pmI actually got it off eBay, I was ordering some cables when I came across it for $3 so I thought "why not". It looked interesting not to mention a great example of 1980's technology on a single board (complete with crinkly solder mask on the other side).

author: SeanB
author_rank: Super Contributor
timestamp: February 03, 2014, 06:45:45 pm
content: I have a similar data concentrator, but this uses a TMS9000 processor and support chips to do the switching between the connected terminals and the modem link to the mainframe. Your one probably served to connect VT100 terminals ( or later PC's running terminal emulation) to an IBM mini.

author: electronics man
author_rank: Frequent Contributor
timestamp: February 03, 2014, 06:51:35 pm
content: It also looks totally auto routed due to the horizontal traces