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Thread: Apple IIe clone ASIC STK chips help required

  1. #11
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    My programming needs are simple. Some diagnostic ROMs that I've acquired (including yours) for vintage stuff, burning some new ROMs for Plus hard-cards and, mostly, 27C chip work.

    The worst thing is, all the various and sundry chips have arrived long ago and everything is waiting on the programmer, as per Murphy's Law....
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

  2. Default

    Quote Originally Posted by David_M View Post
    It doesn't require the RAM to be fu7lly functional.
    This is not exactly true. The 6502 needs the first two zero pages ($0000-$01FF) in order to run properly.
    Moreover, the display uses $0400-$07FF for page 1.
    So you do need at least 8K of working RAM to use the ROM diagnostic.
    Antony
    Apple II forever

  3. #13
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    The ROM I was talking about does not require fully functional RAM because it does not use CALLs and as such does not require stack memory to be working.
    I have used the ROM to boot boards with faulty RAM in bank 0, I've even removed one or two RAM's from bank 0 and it still boots.

    Secondly $0400-$07FF falls within the first 2K of RAM, program memory starts at $0800, enabling the normal F8 boot ROM and applesoft or integer basic to run with 4k of RAM. In fact the Apple 2 originally shipped with as little as 4K of RAM.

    Quote Originally Posted by amauget View Post
    This is not exactly true. The 6502 needs the first two zero pages ($0000-$01FF) in order to run properly.
    Moreover, the display uses $0400-$07FF for page 1.
    So you do need at least 8K of working RAM to use the ROM diagnostic.

  4. Default

    Quote Originally Posted by David_M View Post
    I have used the ROM to boot boards with faulty RAM in bank 0, I've even removed one or two RAM's from bank 0 and it still boots.
    Weird, I've tried the F8 ROM in an Apple II+. If I remove one RAM on row C, the only thing I get is a non booting machine.
    Doing the same on row D or E report an error as expected.
    I will try the IIe ROM and report back here.

    Quote Originally Posted by David_M View Post
    ISecondly $0400-$07FF falls within the first 2K of RAM, program memory starts at $0800, enabling the normal F8 boot ROM and applesoft or integer basic to run with 4k of RAM. In fact the Apple 2 originally shipped with as little as 4K of RAM.
    You are right.
    Antony
    Apple II forever

  5. Default

    I have tested the EF ROM in a IIe.
    Removing a single RAM chip results in an non booting machine.
    Antony
    Apple II forever

  6. #16
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    When I tried pulling a ram the 2e lost all video. However on a board with a faulty address line going to RAM the board would boot with thew ROM but not with the standard EF ROM.

    Quote Originally Posted by amauget View Post
    I have tested the EF ROM in a IIe.
    Removing a single RAM chip results in an non booting machine.

  7. #17
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    OK, I finally, finally got my programmer and made up the ROM for the EF replacement and put it in 2764B (I assume that the A ROM is CD) and nothing happened at all.

    I took out each of the 4 ROMs, one at a time and powered up. With the exception of the 2732 at F4, which gave me a black screen, the display stayed the same.

    Removing the "MMU" and "IOU", one at a time, did nothing to change the display (which I'll have to get a picture of today, so you can see what I'm talking about) and neither did removing the CPU.

    I'm beginning to think that the problem may be, as someone suggested, a socket surface, mechanical or solder problem.

    I'll have to look into that, when time lends itself.

    On the plus side, I did source and get pricing on the STK65301 and STK65371 chips.
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

  8. #18
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    I have a ROM I wrote for the diagnostic card I'm designing, it will work in a 2e with RAM faults.

    Use the 2764 version in the EF ROM socket of your 2e.

    This ROM will work in a system with no RAM at all. It will do 4 RAM tests and beep according to the test results.
    It will also set text mode and output messages to the screen, how visible they are will depend on how bad the fault is.
    The order of the sets are as follows...
    Zero fill test - One long beep if this fails.
    Ones fill test - Two long beeps if this fails.
    Walking one - Three long Beeps on fail.
    Walking Zero - Four long beeps on fail.

    If you hear 5 short higher tone beeps then all tests passed.

    If you hear nothing then you should look at the data and address buses or the IOU decoding of the speaker address.

    Here is a link to the ROM
    Diag ROM beta

    I just had a quick look at the photo you originally posted. The ROM on the bottom right of the board is the keyboard translation ROM, the one on the bottom left is the character generator rom. The two ROMS in the middle of the board are the CD and EF ROMS, which of them is the EF ROM I dont know but it is the EF rom that should be replaced with the diag ROM. If you have 2 2764's you can program... put one in each it wont hurt.
    Last edited by David_M; April 5th, 2017 at 09:33 AM.

  9. #19
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    OK, I tried both the EF ROMs, even doing a combination of all 3 in the 2764A and 2764B sockets. No sounds.

    They worked fine in my Apple IIe

    Would these boards use copies of the actual IIe ROMS?

    I ask because the 2732 @ F4 is considerably warmer than the other 3 ROMs.

    I've attached a picture of what I get on the screen below. It is not precisely the same all the time, but, pretty representative.

    I'm going to have to determine if all the IOU pins on the chip are the same as its STK equivalent.
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    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

  10. #20
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    No sound is not as great sign, but it does tell us RAM is not a problem (yet).
    The fact that there is no change on the screen or sound with the ROM in place gives a few clues.
    I'd be looking again at the CPU, data and address buffers. Double check you didnt accidentally bend a pin putting them back after your first round of testing.

    If you suspect the 2732 thats an easy check, just read the data from it in your new eprom burner.

    They do use copies of the IIe ROM's sometimes with a name change patch. However, Apple do a sneaky thing, the masked programmed version of their ROMS use the unused pin as an extra enable line which from memory needs to be tied low. That line is wired up on the mainboard for the masked ROM's and ignored when you use EPROM's in the board. But the masked ROM's read as blank in an EPROM burner because that extra line is not asserted. So you wont be able to read the chips to copy them, download the binary image of the ROM if you need it.

    I have 6 faulty IIe clone boards here but they all have different layouts and missing chips, some don't identify what chip belongs in the empty socket and most have no ROM's.
    What I have tried is putting the STK chips in a real IIe and I found they don't have the same pinout.

    I do have one complete clone mainboard here, it is only populated with a 27128 in the 2764B position, the 2764A position does not have a socket fitted.
    Some good news however, the working board I have happens to be the same as the one you have. So I can assure you that my diag ROM in a 2764 should work in the 2764B socket of your board because it works in mine. If you need working copies of the other ROM's let me know and I can read the data from these ones and upload them.

    Its a shame you are not local, I could test your STK chips in this board.

    Edit: I decided to read the EPROMS for you just in case.
    https://drive.google.com/open?id=0B8...HpjRVJIbDZfNFU

    Quote Originally Posted by Druid6900 View Post
    OK, I tried both the EF ROMs, even doing a combination of all 3 in the 2764A and 2764B sockets. No sounds.

    They worked fine in my Apple IIe

    Would these boards use copies of the actual IIe ROMS?

    I ask because the 2732 @ F4 is considerably warmer than the other 3 ROMs.

    I've attached a picture of what I get on the screen below. It is not precisely the same all the time, but, pretty representative.

    I'm going to have to determine if all the IOU pins on the chip are the same as its STK equivalent.
    Last edited by David_M; April 6th, 2017 at 04:36 PM.

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