14th Apr 2021, 7:13 pm
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#1640
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Octode
Join Date: May 2012
Location: Perth, Scotland
Posts: 1,817
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Re: Non-working Commodore PET 3016
First result 0
Second result 126.
Does that match what is supposed to happen?
Colin.
Quote:
Originally Posted by SiriusHardware
Well, now that you are able to issue BASIC commands you can try these for a first-line check of the IEEE 488 port. This port is probably only important if you plan to acquire a disc drive or something which pretends it is one, such as the SD2PET.
Notice the POKE address is slightly different to the PEEK address in both cases.
Code:
POKE 59426,0
PRINT PEEK(59424)
Result=?
Code:
POKE 59426,255
PRINT PEEK(59424)
Result =?
The IEEE port has an unusually useful structure in so far as the state of the output latches can be read by the input buffers, so you can write a value to the 8 data bits of the IEEE port and read that value back, in the process proving both the output latches and the input buffers - provided the value you read back in is the same as the value you wrote out.
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