Can anybody supply or recommend a 3 or 4 channel 12 bit dac output card for the ISA slots. I need to supply +/-10 volts to control my servo drives.

Cheers !

Check out Contec http://www.contecusa.com/?page=prod_l2&id=58&cat_id=4&CFID=51344&CFTOKEN=77254636 they supply a good line of cards analogue as well as Digital i/o. Some come up on ebay from time to time.
Al

Don't bother to buy an isa card. It is a major problem to deal with and there are alternatives, such as usb. I've been trying to save a machine that uses an Isa card, and there really aren't any good motherboards at this time that have the slots. There's a P4 Soyo that has ISA, but it isn't worth your time and is very expensive. The computers that have ISA slots are pretty much getting to the end of their useful life. They're dying like flys in my labs at work. And ISA is a real resouce hog that slows down your entire system.

Data acquisition will probably move very quickly to PCI express, so USB may be your best bet at this time for new hardware.

unterhaus:

I totally agree with you about these old machines being dead in the water, but that is precisely why I'm interested in them, people are giving them away!
With the addition of a $300 ISA analogue output card I have converted my old 486pc into a dedicated CNC control. It's a case of recycling, teaching old dogs new tricks, etc. As you say ISA cards are becoming rare items and I am looking for alternative suppliers.

If you're up to making PCBs you could put together your own ISA card for very little money. If you use the XT (8-bit) standard and I/O mode under DOS it's actually suprisingly simple, both the software and the hardware.

I made an ISA card as a high school project. It had a chip from the 74HCT series for address decoding (it just matches the address lines on the bus with some pre-set input) and when they match it lets the DATA signals through to a latch. It had two rows of 8 LEDs each that I could make to blink or scroll. (Yep, that's all it did :) .)

Maxim has a lot of DACs - I'm sure you can find a parallel input 4-channel 12-bit DAC (or at least a 2-channel one) on their webpage (www.maxim-ic.com). They send free samples. +/-12 V and +5 V is available from the bus. It really doesn't get any better than this! :D

The software is even simpler - just use the in and out assembler instructions for writing to or reading from the card. But I guess you know this already since you're writing your own software?

Unfortunately I cannot find my software (it was only a few lines of Pascal code), but the reference I used was http://www.hardwarebook.net/ (Connectors -> Buses -> ISA/ISA technical).

Again, "simple" is assuming that you write your own software and run a non-multitasking OS (like DOS).

Arvid

I actually considered making that ISA board. I have the ISA prototype boards and the DACs. The DACs are 'DAC8412F' from analog devices
www.analog.com, they are quad 12 bit dacs with bi-polar +/-10 volt outputs.
The reason I didn't continue was because I needed all the hardware for my project to be available as standard off the shelf items.

I agree that 'simple' does relate to DOS and the ISA addressing mode.Things start to get a bit more complex when you move to the PCI bus and the windows plug and play system, but DOS is good at running these low level motion control routines. I refer to my previous post if a simple DOS machine will run the motors at Maximum speed how can a more powerful computer make them go faster.

If anybody wants to build arvid's board you can have the bits and I'll test it in my system.