Given that the computer is running the Alpha v4 monitor for EEPROM at 0x0000, and given that a level-change from low to high triggers an essentially call to fixed address 0x3C
then a user module, whether in ROM or in RAM, doesn't have the opportunity to install its own interrupt handler, since the 0x003C address is a fixed jump to the serial status routine.
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0036 SYSTAB: |
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0036 C3 00 00 JMP RESET |
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0039 C3 B9 00 JMP WARM |
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003C C3 AD 00 JMP SERST |
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003F C3 A4 00 JMP SERIN |
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0042 C3 8A 00 JMP SEROUT |
Other interrupts are also pointing in the middle of some routine.
It would be nice to change monitor to e.g. make it fetch the ISR routine address from RAM so that user modules can respond to interrupts, too.
Given that the computer is running the Alpha v4 monitor for EEPROM at 0x0000, and given that a level-change from low to high triggers an essentially call to fixed address 0x3C
then a user module, whether in ROM or in RAM, doesn't have the opportunity to install its own interrupt handler, since the 0x003C address is a fixed jump to the serial status routine.
alpha/sw/Monitor/v4/alpha-mon4.lst
Lines 38 to 43 in bcbedb1
Other interrupts are also pointing in the middle of some routine.
It would be nice to change monitor to e.g. make it fetch the ISR routine address from RAM so that user modules can respond to interrupts, too.