Hello everyone,
I would like to use my old IIe-compatible motherboard, which I used to run with an external II+ keyboard, in an IIe case.
The original IIe has a 24-pin keyboard ROM, but this motherboard has a 28-pin socket. What kind of EPROM is used there? I assume the content should be Keyboard-German-341-0151-A-2716.bin.I would be grateful for any information.
Best regards,
Wolfgang
Most likely 2764. Do you have the make/model of the motherboard? You might be able to find it on the reverse side.
IIe_comp_back.jpeg
If you are putting a 2716 ROM image into a 2764 ROM chip, make sure to create a new ROM image where the original repeats 4 times. Don't just leave the rest blank.
If it's still not working, try filling the 2764 with completely random data. This will allow you to test that everything is working and that the 2764 is indeed the right chip to use. The keys will not correspond to the correct characters, but pressing the same key should always produce the same character on the screen.
That's how I did it, if I remember correctly. I expressed myself unclearly, sorry.
That's a good tip. I'll give it a try. However, I don't think I'll have time this year, but I'll let you know as soon as I've tested it.
Thank you very much for your help and Merry Christmas.
Wolfgang
In case the random data produces results, there is a test ROM image and a program by S.Elliott you can try that should help you figure out the mapping and make your own custom ROM with the correct mapping. I did this 3 years ago when I wanted to use the keyboard encoder from my Apple II+ in my Apple IIe.
You can find it in this post: https://www.applefritter.com/comment/99793#comment-99793
The Mainboard has a keyboard controller installed. It does not need a keyboard rom since it is integrated inside the keyboard contrller. You simply connect the IIe style Keyboard to the connector besides the keyboard controller. These clone-mainboards are a one-fits-all solution and were designed to be retrofitted into a II+, IIe or clone-case.
-Jonas
It is quite possible that this motherboard doesn’t need a keyboard ROM if connected to an Apple II+ keyboard, which already has a keyboard controller (the AY5-3600-931) with the Apple II+ specific mapping inside the chip itself. However, when used with an Apple IIe keyboard it definitely needs a ROM chip, since the AY-5-3600-PRO's internal mapping is generic and the keyboard ROM is required to remap it to the keyboard of the Apple IIe.
I used to run the motherboard in an external IBM-style case with an external Apple II+ keyboard. I implemented the Apple keys via the joystick.
But the old case has been disposed of and I want to run the board in an IIe case with a corresponding keyboard.
I'm guessing jumpers X5-8 are used to select EPROM size. Might work. with 2716 installed into lower portion of socket.
More likely that it can't use a keyboard ROM if connected to an Apple II+ keyboard. The reverse side of the motherboard suggests that the LS374 is fed from both the keyboard ROM and the LS373 transparent latch from the Apple II+ keyboard socket.
It looks like the circuit can have an LS373 installed or a keyboard ROM installed, but probably not both at the same time. If it was my system, I would use a continuity meter to test if the outputs from the LS373 are interconnected with the outputs of the ROM socket. If any of pins 2, 5, 6, 9, 12, 15, 16, 19 at the LS373 are interconnected with any of the pins 11, 12, 13, 15, 16, 17, 18, 19 at the ROM socket, then both sockets cannot be populated at the same time. (ie: the LS373 must be removed if a keyboard rom is installed)
You are right. I have an identical mainboard that has (on closer inspection) seemingly another keyboard controller in the "3600-pro" socket and no keyboard rom. It works without problems and even has makros (on the keycaps of a IIe style keyboard) that work as well. My keyboard controller has the markings removed with sandpaper. I was a bit thrown off because my IIe clone keyboard works without a rom.
I may have another of these clones-mainboards somewhere. I once bought a batch of these boards from italy. Some had defective STK MMU or IOU clone chips and i got 2 or 3 running after swapping parts around. The defective STK-chips were sent to someone who wanted to decapsulate them. I have not heard back from them, though.
Please excuse the long break; unfortunately, I have only just been able to look at the motherboard.
You are correct, some of the pins listed for the LS373 were connected to pins on the ROM socket.
I removed the LS373 and, as suggested by jeffmazur, inserted a 2716 into the socket. I was unable to make any entries with the connected IIe keyboard. Only the Apple keys, Control and Reset keys worked, which ran a self-test.
I then burned the keyboard ROM twice in a row into a 2732, but that didn't work either. I had deleted the 2764 in the meantime, so now I can't reprogram it. I've ordered a new one.
When I plug a PS/2 adapter into the keyboard connector with an empty keyboard ROM socket, I can type without any problems when the LS373 is inserted. However, since I want to install the motherboard in an IIe case, this is not an option.
Thank you very much for your help and patience. I am now waiting for a new 2764.
Wolfgang