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81 lines
3.7 KiB
Markdown
81 lines
3.7 KiB
Markdown
# Known issues
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The issues of the w11 CPU are listed in a separate document
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[w11a_known_issues.md](w11a_known_issues.md).
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This file descibes general issues.
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The case id indicates the release when the issue was first recognized.
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### V0.73-3 {[issue #11](https://github.com/wfjm/w11/issues/11)}
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The 'state number generator' code in `pdp11_sequencer` causes in vivado
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2016.1 (and .2) that the main FSM isn't re-coded anymore, which has high
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impact on achievable clock rate. The two optional debug units depending on
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the state number, `dmscnt` and `dmcmon`, are therefore currently deactivated in
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all Artix based systems (but are available on all Spartan based systems).
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Issue is still in Vivado 2016.4. `dmcmon` can be enabled if wanted, this
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might require a reduced clock rate. See procedure given in
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[comment to issue #11](https://github.com/wfjm/w11/issues/11).
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### V0.73-2 {[issue #10](https://github.com/wfjm/w11/issues/10)}
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Many post-synthesis functional and especially post-routing timing
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simulations currently fail due to startup and initialization problems.
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Cause is MMCM/PLL startup, which is not properly reflected in the test
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bench. Will be resolved in an upcoming release.
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### V0.73-1 {[issue #9](https://github.com/wfjm/w11/issues/9)}
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as of vivado 2016.2 `xelab` shows sometimes extremely long build times,
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especially for generated post-synthesis vhdl models. But also building a
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behavioral simulation for a w11a design can take 25 min. Even though
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post-synthesis or post-routing models are now generated in verilog working
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with `xsim` is cumbersome and time consuming.
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### V0.66-1 {[issue #8](https://github.com/wfjm/w11/issues/8)}
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the TM11 controller transfers data byte wise (all disk do it 16bit
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word wise) and allows for odd byte length transfers. Odd length transfers
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are currently not supported and rejected as invalid command. Odd byte
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length records aren't used by OS, so in practice this limitation
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isn't relevant.
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### V0.65-2 {[issue #7](https://github.com/wfjm/w11/issues/7)}
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some exotic RH70/RP/RM features and conditions not implemented yet
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- last block transfered flag (in DS)
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- `CS2.BAI` currently ignored and not handled
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- read or write 'with header' gives currently `ILF`
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All this isn't used by any OS, so in practice not relevant.
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### V0.65-1 {[issue #6](https://github.com/wfjm/w11/issues/6)}
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`ti_rri` sometimes crashes in normal rundown (exit or ^D) when
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a `cuff:` type rlink is active. One gets
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```
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terminate called after throwing an instance of 'Retro::Rexception'
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what(): RlinkPortCuff::Cleanup(): driver thread failed to stop
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```
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Doesn't affect normal operation, will be fixed in upcoming release.
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### V0.64-6 {[issue #5](https://github.com/wfjm/w11/issues/5)}
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IO delays still unconstraint in Vivado. All critical IOs use
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explicitly IOB flops, thus timing well defined.
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### V0.64-2 {[issue #4](https://github.com/wfjm/w11/issues/4)}
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rlink throughput on basys3/nexys4 limited by serial port stack
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round trip times. Will be overcome by libusb based custom driver.
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### V0.64-1 {[issue #3](https://github.com/wfjm/w11/issues/3)}
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The large default transfer size for disk accesses leads to bad
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throughput in the DL11 emulation for low speed links, like the
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460kBaud the S3board is limited to. Will be overcome by a DL11
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controller with more buffering.
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### V0.62-2 {[issue #2](https://github.com/wfjm/w11/issues/2)}
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rlink v4 error recovery not yet implemented, will crash on error.
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### V0.62-1 {[issue #1](https://github.com/wfjm/w11/issues/1)}
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rlink command lists aren't split to fit in retransmit buffer size.
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_{the last two issues are not relevant for w11 backend over USB usage because
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the backend produces proper command lists and the USB channel is usually error
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free}_
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