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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 5th Oct 2023, 4:32 pm   #1
Join Date: Aug 2023
Location: Gateshead, Tyne and Wear, UK
Posts: 11
Default Nec v25

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This SV25 microcontroller card dates back to the early 90s. So maybe not quite vintage but getting there.

It makes use of an NEC V25 microprocessor which is a microcontroller version of the V20.
(Which is in turn an 8088 machine code compatible processor with additional functionality).

The V25 contains twin RS232 interfaces and assorted extras:
* 2 16-bit timers
* DRAM refresh control unit
* 4 Input lines and 20 I/O lines
* 2-channel DMA controller
* 8-level interrupt controller

Bit of a latterday RaspberryPi ;-)

The card accepts an assorted range of RAM and PROM devices which are selectable using the links on the pcb.

The SV25 card has an STE bus connector with a terminator adapter which is also used to connect the 5v power rail.

We made use of these cards in a real time project as part of my job during the early 90s. I saved this one from the skip during a building move.

Sadly I did not hang on to the documentation. I have traced the board jumpers for RAM and ROM so have the relevant info for those, as well as the serial interfaces. The rest will be worked out as and when (and if) I need to use it.

It has the original monitor program in eprom which was never really used. This provided basic memory access and a data load facility.

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Still a nice piece though.
terrystokoe is offline  
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