Updated the source after the previous bug in addressing the videoram vanished. I tried to add Cluso99's PASM debugger to q6502.spin and in the course broke the emulation. After reverting to the q6502 from version 0.1.3 and applying some of the changes I had done for the debugger, now the bug is gone. I don't have a clue yet which of the changes made the difference. It could be one of moving the io_command and irq variables to the DAT section, or moving the videoram and graphicsram into the io.spin object instead of microtan.spin.
Anyway, now scrolling works as expected. However the output of Tanbug listing memory with e.g. LC000,0 is ultimately slow. I don't know if this is due to another emulation bug, or if perhaps Tanbug itself is slowing down the output. Does anyone remember using Tanbug?
Did you say you needed a joystick for this emulation? Just brainstorming what could be done with 8 new digital inputs and 8 digital outputs on a new board design...
Dr_Acula said...
Did you say you needed a joystick for this emulation? Just brainstorming what could be done with 8 new digital inputs and 8 digital outputs on a new board design...
All available programs rely on two 6522 VIAs and one or two joysticks connected to the parallel ports. I have yet to emulate the 6522 registers and their function: timers, parallel in/out, interrupts on trigger pins etc. - not easy to squeeze this into io.spin.
I found the cause for the tremendous slowdown: the interrupt request wasn't cleared by the take interrupt function, because usually an interrupt handler de-asserts the IRQ on its own. For some reason this doesn't seem to be the case with the keyboard IRQ (the only one in Microtan) and so the interrupt code was executed over and over again, executing only one non-interrupt instruction in between IRQs.
Now the output of listing a memory block is reasonably fast.
Next thing to do is add the VIA 6522 emulation to get the joystick(s) simulated.
I just saw a post by Holly about the 6502 and the Apple over on the sandbox forum. Back in the day, like VHS vs Beta, you were 65xx or xx80 and I fell into the latter group - 8080, Z80, 8086 etc, so I'm not as familiar with the 65xx group of computers.
But from my limited recall, I think it was this Microtan, Apples, Commodores? and I'm sure there are others.
When pullmoll got CP/M working, suddenly we saw new computer emulations every few days. So I'm eagerly looking forward to the microtan working as I think it might pave the way for another burst of activity and new emulations.
The Microtan is basically working. There are most probably bugs to fix in the 6502 (6510) emulation. I should look out for some 6502 exerciser program to run and see where it fails. The second thing to do is to emulate the VIA 6522, because it seems to be vital for the existing games on the Microtan.
Comments
Anyway, now scrolling works as expected. However the output of Tanbug listing memory with e.g. LC000,0 is ultimately slow. I don't know if this is due to another emulation bug, or if perhaps Tanbug itself is slowing down the output. Does anyone remember using Tanbug?
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Pullmoll's Propeller Projects
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www.smarthome.viviti.com/propeller
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Pullmoll's Propeller Projects
Now the output of listing a memory block is reasonably fast.
Next thing to do is add the VIA 6522 emulation to get the joystick(s) simulated.
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Pullmoll's Propeller Projects
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http://www.propgfx.co.uk/forum/·home of the PropGFX Lite
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I just saw a post by Holly about the 6502 and the Apple over on the sandbox forum. Back in the day, like VHS vs Beta, you were 65xx or xx80 and I fell into the latter group - 8080, Z80, 8086 etc, so I'm not as familiar with the 65xx group of computers.
But from my limited recall, I think it was this Microtan, Apples, Commodores? and I'm sure there are others.
When pullmoll got CP/M working, suddenly we saw new computer emulations every few days. So I'm eagerly looking forward to the microtan working as I think it might pave the way for another burst of activity and new emulations.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.smarthome.viviti.com/propeller
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Pullmoll's Propeller Projects