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Commit Graph

13 Commits

Author SHA1 Message Date
Peter Evans
978ad1faaf Formerly "BAD" instructions are now forms of NOPs
But weird forms. In most cases they basically are NOPs, except with
different opcodes. In other cases, we call them NP2 and NP3s, and do so
because they consume 2 or 3 bytes respectively (vs. just 1 with NOP).

We had to teach some arcane magic to the emulator for this to work. We
may want to refactor to decouple the number of bytes consumed from the
address mode.
2018-02-22 14:07:05 -06:00
Peter Evans
90892c32e4 Add TSB (Test and Set Bits) instruction
This commit also moves the TRB code from loadstor to bits, which is
where it should have been all along.
2018-02-22 13:39:48 -06:00
Peter Evans
a4c3d1c4ef Implement the TRB (Test and Reset Bits) instruction 2018-02-22 00:39:33 -06:00
Peter Evans
807362e871 Add STZ instruction (to store zero) 2018-02-22 00:02:57 -06:00
Peter Evans
8e1ab0e950 Add support for PHX, PHY, PLX, PLY
These instructions allow you to push and pull (pop) the X and Y
registers via the stack.
2018-02-21 23:32:57 -06:00
Peter Evans
f9a277e7bc Add new Branch Always instruction 2018-02-21 21:57:21 -06:00
Peter Evans
7b65dc1657 Add new BIM instruction (BIt imMediate mode)
This is not a real instruction in the 65c02 processor; I invented it for
the sole purpose of handling the specialized logic that is performed by
BIT in IMM mode. To be fair--I can imagine this really _was_ implemented
as a "separate" instruction on the chip! But I don't know that for sure.
2018-02-21 21:01:46 -06:00
Peter Evans
945bf23f22 Use correct default status and memory mode 2018-01-21 21:33:12 -06:00
Peter Evans
ecd8a7974a Add "BAD" instruction to crash when we hit an invalid opcode 2018-01-21 12:48:34 -06:00
Peter Evans
2f777ce881 Several core changes to status, soft switches
Regarding soft switches, we had several we should have been listening
for on both reads and writes, but were only doing so on writes; this is
now fixed.

Regarding statuses, we were incorrectly calculating both carry and
overflow. This should now be fixed, although some quick examinations of
disassembly output suggest there is something else amiss. Debugging will
continue shortly.
2018-01-20 21:01:26 -06:00
Peter Evans
1de1e7788a Rename status flags to MOS_ 2018-01-05 14:18:39 -06:00
Peter Evans
8cd9c5ffab Documentation, lacking 2017-12-06 21:25:47 -06:00
Peter Evans
3cebed2377 Adding all of the instruction files 2017-12-02 13:05:53 -06:00