Lots and lots! Many of my (personal) VAXen and PDP-11s have cards from Emulex, Dilog, etc. One of my PDP-8s has a card from Data Systems Design. That's just some DECworld examples, but there were tons of third-party peripherals for most minicomputers. -Dave On 5/22/23 22:09, Douglas Crawford via vcf-midatlantic wrote:
Thanks that a great short overview of the DEC side, thanks. Did the minicomputers gather much 3rd party support for cards on their buses? I'm going to guess some, but not near as much as what happened in microcomputers, perhaps simply due to installed base/market size being relatively larger on the microcomputer platforms.
On 5/22/2023 8:00 PM, Ethan Dicks via vcf-midatlantic wrote:
On Mon, May 22, 2023 at 11:58 AM Douglas Crawford via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
Slots were important to make these machines versatile and created entire sub industries around each machine that had slots. I'm less versed in the slot systems of the minicomputers; I imagine a certain amount of this dynamic occurred there too.
Depends on the specific minicomputer, and to an extent, the era, but starting in 1970, DEC went from random-wired logic to a bus system with the Unibus in the PDP-11/20. They started with backplane-scale "system modules" that were bridged together such that the Unibus was at the start and end of a backplane block (and the middle could still be random-wired logic) but that quickly (1972) evolved to one slot after another just being "Unibus" (there are some power supply pin variations but the basic signals are the same from slot to slot). The CPU goes at the top but I/O cards follow a set of priority rules as to the order that follows. From the top side, the slots all look the same, like an embedded PC backplane that is 100% ISA slots with the CPU on an ISA card.
Following from the PDP-11 Unibus is the PDP-8 Omnibus (a bus of busses) where all the slots are exactly identical.
Then the Qbus came along and though there are a couple different wiring schemes (Q18, Q22, CD-slots, straight-down vs serpentine) but it's not a free-for-all - there are really only a handful of arrangements one encounters.
There are details that one might recognize from microcomputer "slots" and there are some differences. In broad terms, with minicomputers, it's not unusual to see the CPU and memory and peripherals either on the same bus structure, or sometimes there are dedicated memory slots and dedicated peripheral slots that may or may not use the same connectors. It's not as straightforward as, say, the ISA bus or the Apple II slot scheme. The closest examples of structural resemblances that come to mine are, for one, the Omnibus and the S-100 bus.
This is just one vendor. There is something visually similar with Data General Nova systems but I'm not experienced enough to comment on them.
There's more but I wanted to at least throw some words out there about some of the more popular minis.
-ethan
-- Dave McGuire, AK4HZ New Kensington, PA