

>>>>>>>>  TEST6000


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TARGET
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This is 32 KB sized code to go into ROM U18 (which is 32 KB sized) on an IBM 5160 (IBM XT) motherboard.

If your IBM 5160 motherboard is a 64-256KB type, the TMM23256/MK37000/MK38000 ROM's can in most cases be replaced with 27C256 EPROM's,
but some brands of 27C256 may be unsuitable for the 64-256KB motherboard - see http://www.minuszerodegrees.net/5160/motherboard/5160_u18_u19_sockets.htm
     
If your IBM 5160 motherboard is a 256-640KB type, then you can use a 27C256 (or 27256) EPROM, or a Winbond W27E257.
      
For the IBM 5160, use EPROM's that are rated at 250 ns, or faster.
See http://www.minuszerodegrees.net/5160/motherboard/IBM%205160%20motherboard%20-%20ROM%20description%20from%20TR.png


The code also suits XT clones that have a single 32 KB sized BIOS ROM (e.g. 27256 or 27C256).
If the XT clone has instead, a single 8 KB sized BIOS ROM (e.g. 2764 or 27C64), then use the 8 KB sized ROM images at http://www.minuszerodegrees.net/5150/code/IBM%205150%20-%20Some%20test%20code%20for%20U33.htm


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REQUIRED
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1. A parallel (LPT) port POST code reader.
   See http://www.minuszerodegrees.net/images4/Parallel%20port%20monitoring%20POST%20board.jpg

2. A parallel (LPT) port on your computer that is at one of the following I/O addresses: 378 or 278 or 3BC

3. A way of putting TEST6000_32KB_SIZED.BIN into a suitable ROM/EPROM/EEPROM.


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WHAT DOES THE CODE DO ?
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All that the code does is send the 4 bytes of {00}{FF}{55}{AA}, in that order, to LPT ports 378, 278, and 3BC, then it halts the CPU.

(There is a small delay between the 4 bytes, otherwise, as I discovered, the parallel port code reader misses bytes.)


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WHAT YOU SHOULD OBSERVE
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The last (repeat: last) 4 codes/bytes seen on your parallel port code reader should be {00}{FF}{55}{AA}, in that order.


If you are using the aforementioned reader:

1. [55][AA] will be the final display shown.

2. You then use the NEXT button as many times as required to see a history of the bytes received (received after power on of the reader).
   Example follows:
   [00][65]  <---- First byte received was 65 hex. Noise? Ignore it.
   [01][FF]  <---- Second byte received was FF hex. Noise? Ignore it.
   [02][E3]  <---- Third byte received was E3 hex. Noise? Ignore it.
   [03][44]  <---- Fourth byte received was 44 hex. Noise? Ignore it.
   [04][00]  <---- GOOD
   [05][FF]  <---- GOOD 
   [06][55]  <---- GOOD 
   [07][AA]  <---- GOOD 

   Above, I used the NEXT button to go back all the way to the first byte received.
   I did not need to do that.
   I really only needed to push the NEXT button four times, to see the LAST four bytes received.



