[vcf-midatlantic] 8-bit ISA slot Single Board Computer

Joseph Oprysko joprysko1 at gmail.com
Tue Sep 20 14:49:08 EDT 2016

Thanks Herb. :)

On Tuesday, September 20, 2016, Herb Johnson via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

> Joseph Oprysko posted:
> Is anyone here aware of such a beast?  I have a Heathkit/Zenith Z-150
>> system. It's motherboard is literally just an 8-Bit ISA backplane, the
>> computer occupies 4 of the ISA slots.
> I have Z-150 and related documentation. Zenith/Heath produced a number of
> models of ISA computers which used passive backplanes and several ISA
> boards to complete the PC-nearly-compatible computer. Other Zenith products
> used IBM-type motherboards with most of the PC functions on that board.
> http://www.retrotechnology.com/herbs_stuff/zenith_mans.html#z148
> I'm curious if there exists a Single Board Computer that would work in the
>> 8-bit slots.
>> What I would actually like to try is to have multiple SBC's on the ISA
>> bus,
>> and have them communicate with each other.
> There may be single-board PC's which fit a single 8-bit ISA slot. But many
> were 16-bit ISA, the longer slot. And the PC-104 stackable bus standard, is
> essentially the ISA bus on a different connector. YOu can look up PC-104 if
> that's not familiar.
> Running multiple ISA-bus "masters" on one ISA bus, may be a problem.
> Briefly: they each expect to drive the bus as a single master. There may be
> products that can share the bus with each other.
> (shrug) you'll have to do some homework to become familiar with such
> things; and then of course find now-vintage products which will share the
> bus; and of course determine how to set them up, boot up sequences, who is
> in charge when, and so on.
> Likely more common, are slave CPU boards, where a task or a user gets a
> CPU on a board with memory and I/O; but uses the bus to share resources
> like hard drives. this was common in S-100 TurboDOS systems. Some of the
> S-100 "IEEE-696" CPU boards, can release the bus to another CPU or DMA
> bus-master; some of those boards are fairly functional "computers".
> Multibus did this too.
> But I'm guessing the idea, is to use IBM-PC ISA-class products, to check
> out multiple bus-masters and multiple CPU's, in a vintage way. a modified
> ISA backplane, may be such a way. A custom backplane may be able to adapt
> ISA "no share" bus masters to access common ISA bus devices. But you might
> look at PC-104; they are smaller cards, more integrated and so with more
> features; and they may have a multi-master standard as part of PC-104. And
> of course, they are vintage now. ;)
> Herb JOhnson
> --
> Herbert R. Johnson,  New Jersey USA
> http://www.retrotechnology.com OR .net

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