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IBM 5160 Slot 8 MOD

ibmapc

ibmapc

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Anyone with access to schematic for the 5160 motherboard and the ability to interpret same feel like answering a question?
I'd like to know if it is possible to modify slot 8 to work the same as the others so that most any card can be used there. Maybe with some cutting and jumping of some traces?
All other slots are full, and my joystick adapter won't work in slot 8. Maybe one of the other cards could work there, but I have not yet tried.

Thanks

Greg
 
The problem with slot 8 is that it's on a whole different bus than the other slots. While slot 1-7 is on the main bus, slot 8 is on the parallel system bus.

Slot 8 is not actually that different otherwise. Cards using it has only two special requirements: 1. They need a piece of logic that generates the /cardselect signal on reads (for the bus transceiver between the two busses), and 2. They must not use DMA at all. As mentioned, more or less any 8-bit async adapter or half-length modem fulfills both these requirements.

It should, however, be possible to modify the joystic adapter to work in slot 8. Just OR together the /CE signal generated somewhere on the card and the /IOR signal from the ISA bus (they may even have been OR-ed together somewhere on the card already), and return the output on the /Cardselect line of the bus.
 
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Chuck(G) said:
If you've got an IBM async card, that will work just ine in slot 8, if that's any help.
Click to expand...

The closest thing I have in there is a Kouwel serial/parallel card. I wonder if that will work in slot 8?

per said:
The problem with slot 8 is that it's on a whole different bus than the other slots. While slot 1-7 is on the main bus, slot 8 is on the parallel system bus.

Slot 8 is not actually that different otherwise. Cards using it has only two special requirements: 1. They need a piece of logic that generates the /cardselect signal on reads (for the bus transceiver between the two busses), and 2. They must not use DMA at all. As mentioned, more or less any 8-bit async adapter or half-length modem fulfills both these requirements.

It should, however, be possible to modify the joystic adapter to work in slot 8. Just OR together the /CE signal generated somewhere on the card and the /IOR signal from the ISA bus (they may even have been OR-ed together somewhere on the card already), and return the output on the /Cardselect line of the bus.
Click to expand...

Thanks Per, I didn't realize that it was "That different". I'll look at my Joystick Adapter to see if I can figure out what you are talking about.
 
ibmapc said:
Thanks Per, I didn't realize that it was "That different". I'll look at my Joystick Adapter to see if I can figure out what you are talking about.
Click to expand...

Try to trace the address lines used by the card, and figure what chips they go into. The typical address it decodes for is 0x201h, so the card wil activate some output somewhere* when the address present is something like xxxx xxxxxx10 00000001.

(* On the original IBM game controller, this is output 15 of U1, which is OR-ed together with the /IOR signal in U3, and the signal you want to send to /Cardselect is then the signal that outputs at pin 11 of U3.)

Do you have a picture of the card? I guess some later cards uses a PAL for address decoding, which makes it just a little bit harder to figure out, but not much. The chip you should look for is still where the /IOR line and the signals from the address lines meet.
 
per said:
...Do you have a picture of your card?
Click to expand...

I actually have two game adapters. One is a basic one port card and the other is this one:
View attachment 11924View attachment 11926View attachment 11925

Sorry about the lighting on these. I'll get my Good camera out later and take some better pics that will let you see the numbers on the chips.

I'll try to get a picture of the other one later. It may be easier to modify because it's just a basic single port, single speed card and the chips and traces are not as closely spaced.
 
One of the problems with the card pictured, is that only the necessary edge connector traces are present. That makes things a bit difficult because the "card selected" trace isn't one of them. Let's see what else you have with more-or-less complete edge connector traces.
 
I decided to use the "BRUTE FORCE" Technique. I put each card that would fit in slot 8 (pretty tight in my 5155) and tried it out. Results are a little surprising to me. The only card that I have that will work in Slot 8 is the one that I was sure would not. It's the AST HotShot/286 Accelerator Board. This is a good thing. The board is now right next to the CPU socket that it must plug into. A future project is to make a new CPU ribbon cable that is the perfect length. The original one is folded up quite a bit and consumes a fair amount of space. So the problem is "Worked Around".

Thanks for the replies

Greg
 
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I thought the IBM 5161 extender card could go into slot 8, but if that is so, then how would the hard drive controller in the expansion unit, which uses DMA, function?
 
When this came up before, the conclusion was that the card in the 5161 went in the right-most slot, and the card in the 5160 went in the left-most slot. Definitely, DMA transfers *to memory* are not possible from slot 8; the result is that nothing drives the data bus and a parity error NMI is generated.

DMA transfers *from memory* might work, I've not tested that.
 
Great Hierophant said:
I thought the IBM 5161 extender card could go into slot 8, but if that is so, then how would the hard drive controller in the expansion unit, which uses DMA, function?
Click to expand...

The extender/receiver cards only forwards the /cardselect line, so if you place the extender card in slot 8 of the
XT then all the slots in the expansion unit will act like slot 8 of the XT. As mentioned by Peace_jj, that's a really bad idea and should absolutely be avoided.

The confusion problably arises from that IBM may have been suggesting to place the Receiver card in slot 8 of the Expansion Unit. It is not mentioned anywhere at all that the Extender card should be placed in slot 8 of the XT.
 
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