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27

I found this page on the motherboard, which says they are some sort of "32-bit external memory card." What are these slots? They are exactly that, memory expansion. This is a rather early 386 board from before memory modules became a thing. The mainboard can be fitted with 1 MiB using 256 KiBit chips (41256), so any expansion has to go on cards. ...


14

There's basically two possibilities you may find: The ISA card is a fairly trivial piece of hardware, using I/O ports or memory-mapping only. In this case, it is pretty likely an USB-to-ISA or PCI-to-ISA adapter will work. It is, however, also pretty likely a modern PCI-express or USB replacement is cheaper, thus rendering the adapter useless. The ISA card ...


13

No, this sound card is definitely not intended for such a slot that expands the ISA slot to 32 bits. This is a Compaq-specific sound card meant for a Compaq-specific ISA slot extension. There is no more than the six pins for Compaq-specific audio extensions. Based on a few pictures of the card, it simply routes some audio signals between card and backplane. ...


10

Were those slots manufacturer-specific or was there some kind of (unofficial) standard? Manufacturer specific. (Well, there was EISA, but I guess it's safe to assume that this question is explicitly not about EISA) What additional signals were available in these slots? Most likely D16..31 and A24..31. Plus maybe BE0..3 - and that's where the main issue ...


10

Photos of the manual of (nearly) that board appeared on the VOGONs forum in https://www.vogons.org/viewtopic.php?p=844188#p844188 . They clearly spell out that these slots are 32-bit memory slots combined with 8-bit ISA slots. The pinout is included. A single slot has the pins equivalent to two banks of (double-sided) PS/2 SIMMs. So a board with two of those ...


9

If it works and the voltages are within tolerance then it should be OK to use it. The only thing that might affect things is that normal ATX supplies may regulate voltages according to 3.3 V output, so normal ATX supplies may not work properly of there is no load on 3.3 V as AT does not use 3.3 V supply. The PicoPSU may work without 3.3 V load just fine. And ...


8

A proper ISA IDE interface is quite simple, but not as easy as it might sound. There are some strange corner cases you should consider for full AT compatibility. You can find schematics for ISA IDE interface adapters in service manuals of computers slightly newer than you MFM portable computer. For example, check volume II of the Compaq Deskpro 386 technical ...


7

Pull-ups are required (for the lines that are used) but the series resistors are optional. You may wish to place 0Ω links (on /IORC et al.) between the processor's bus and the ISA bus; if you encounter problems these could be replaced with series resistors (e.g. 22Ω, as suggested by Intel). A more common technique1 for bus termination is to use a resisitve ...


6

The classic ISA bus has very little need for bus termination. For example the first IBM PCs, such as the PC, XT and AT for example did not use any bus termination, and their ISA bus worked fine. So, in short the answer is, no you don't have to terminate the bus, as depending on how you do it, it might just make things worse. The cards on the bus are ...


6

The 32-bit extension to ISA was Extended ISA but it doesn’t add any additional connectors, instead adding extra pins to the part of the existing edge connector that is reserved for insulation.


4

As mentioned is a comment above by @scruss, some manufacturers (such as ARS Technologies) have created a USB device that provides an USB-ISA bridge and an ISA slot. It is an expensive option, as it's a niche product, and most people needing this kind of item will be in a position where they have to support some old mission-critical peripheral that can't ...


3

How to build an ATA controller for the AT bus? You can't, as there isn't any. You want to connect IDE-Drives, right? IDE stands for Integrated Device Electronics. Which simply means that the full host controller is already part of the drive. It contains everything that is on your MFM controller, except for bus-buffering, address selection and extension ROM. ...


2

I think this swapbox could be connected to a more modern machine, but it'd require some soldering work to achieve. From looking at the connectors on the cable and card reader, it appears to use a pair of 50-pin IDC ribbon cables. PCMCIA / Cardbus cards have 68 connectors each, however. There doesn't appear to be any duplication of pins (e.g. multiple ...


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