Thread: Mk14 vdu
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Old 1st Jul 2020, 7:26 pm   #104
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,482
Default Re: Mk14 vdu

So to fix your problem we need to exclude 0FFF from what is currently the 0F18-0FFF block upload and keep the byte which needs to go into 0FFF somewhere else until the system is under user program control where a write to 0FFF will be just that, a write to a memory location and not to the status register.

However this still doesn't explain my original problem, that of the execution address appearing in 0FFE-0FFF, only if the code has been auto-run. I don't know if you tried it, but if you don't have the program auto-run after upload and instead run it manually from 0880, there is no corruption of 0FFE-0FFF.

For each line of Intel Hex, the send14 script fetches the address from that line and first looks to see if the address is FFFE, if so it captures the first two data bytes from the line to use as the execution address after upload and then it sets the OutputMode variable to 0 (off) so that as it works through the rest of the line checksumming it as usual, no part of it, neither the address or data, is actually sent out to the MK14. It seems as though the script is somehow seeing this line as a normal line and therefore changing to address FFFE before starting to enter the data (2 bytes) from the line as it would for any other line of data.
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