diff --git a/doc/CHANGELOG.md b/doc/CHANGELOG.md
index 6070364b..d6231e7c 100644
--- a/doc/CHANGELOG.md
+++ b/doc/CHANGELOG.md
@@ -43,7 +43,7 @@ The full set of tests is only run for tagged releases.
   - tools/sys/mcode: added memclr.mac (writes zero into memory)
   - tools/tcode: fast cpu verification codes
   - tools/tests: test programs
-  - tools/bin: added dasm-11, a PDP-11 disassembler
+- tools/bin: added dasm-11, a PDP-11 disassembler
 ### Changes
 - tools changes
   - ci.yml: define TBW_GHDL_OPTS and suppress IEEE package warnings at t=0ms
diff --git a/doc/README_known_issues.md b/doc/README_known_issues.md
index efe530b0..f5fe5bdf 100644
--- a/doc/README_known_issues.md
+++ b/doc/README_known_issues.md
@@ -1,6 +1,7 @@
 # Known issues
-
-The case id indicates the release when the issue was first recognized.
+Notes
+- resolved issues are summarized in [resolved issues](README_resolved_issues.md)
+- the case id indicates the release when the issue was first recognized.
 
 ### V0.791-3 {[issue #35](https://github.com/wfjm/w11/issues/35)} -- MMU: D space used instead of I space for PC deferred specifiers
 
@@ -25,62 +26,6 @@ Clearly a bug.
 Wasn't detected so far because this access mode has no practical value  
 and this therefore not used in normal software.
 
-### V0.791-2 {[issue #34](https://github.com/wfjm/w11/issues/34)} -- MMU: ACF=1 traps on any access
-
-Test 055 of `ekbee1` fails with
-```
-    MEMORY MANAGEMENT TRAP OR ABORT HAD INCORRECT CONDITION
-    EXPECTD ERROR   AUTOI/D VIRTUAL
-    CONDITN REGISTR REGISTR ADDRESS TESTNO  PC AT ABORT
-    020011  030011  013427  054032  000055  054040
-```
-This is caused by a bug in pdp11_mmu. For ACF=1 a trap is taken for any access,
-it should be taken only for read accesses.
-
-### V0.791-1 {[issue #33](https://github.com/wfjm/w11/issues/33)} -- MMU: PDR A bit is set for every access
-
-The `PDR` `A` bit is described in the Technical Manual as
->  A bit (bit 7) - This bit is used by software to determine whether or not  
->  any accesses to this page met the trap condition specified by the Access  
->  Control Field (ACF). (A = I is affirmative). The A bit is used in the  
->  process of gathering Memory Management statistics.
-
-It is set when the page `ACF` enables an MMU trap, thus for
--  ACF=1 and read access
--  ACF=4 and any access
--  ACF=5 and write access
-
-The w11 currently sets the 'A' bit on any non-aborted access regardless of the ACF value.
-
-No practical impact, the 'A' bit in `PDR` is a 11/45 11/70 only feature and not used in OS software.
-
-### V0.79-2 {[issue #30](https://github.com/wfjm/w11/issues/30)} -- SimH scmd files fail on current 4.* version; only 3.* supported
-
-The SimH scmd scripts were originally developed for SimH 3.8, and worked for
-SimH 3.9 and later releases. The SimH 4.* development team decided not to
-provide releases anymore, and over time this version became incompatible with
-the scmd scripts used for w11. That is most pronounced for the RT11 V4.3 oskit.
-A simple
-```
-  cd $RETROBASE/tools/oskit/rt11-53_rl
-  console_starter -s -d DL0  &
-  pdp11 rt11-53_rl_boot.scmd
-```
-works fine for SimH V3.9, V3.10 and V3.11-1, but fails
-- for pdp11-4.0-beta1 with core dump
-- for pdp11-2016-12-26-5ced037b with signal SIGSEGV in pdp11_xu
-- for pdp11-2019-07-28-2f707ffc with signal SIGSEGV in pdp11_xu
-- for pdp11-2020-03-26-261abfc3 with signal SIGSEGV in pdp11_xu
-- for pdp11-2021-08-22-64b12234 with signal SIGSEGV in pdp11_xu
-- for pdp11-2022-04-17-d3f1ee09 with with errors like
-  - Device auto configuration is now disabled
-  - Command not allowed (for set rha enabled)
-  - container incompatible with the RL device
-
-Bottom line:
-- the provided scmd scripts work only with SimH V3.9, V3.10 or V3.11-1
-- an update to the SimH V4.* has low priority
-
 ### V0.50-2 {[issue #28](https://github.com/wfjm/w11/issues/28)} -- RK11: write protect action too slow
 
 Some simple RK11 drivers, especially in test codes, don't poll for completion
@@ -124,43 +69,6 @@ not in the J11, it is not used by common operating systems.
 Therefore this is considered a to be a minor deficit. Will be fixed in an
 upcoming release.
 
-### V0.50-6 {[issue #26](https://github.com/wfjm/w11/issues/26)} -- CPU: MMR0 trap bit set when access aborted
-
-The MMU should set the 'trap bit' in `MMR0` only when the access is not
-aborted. The current pdp11_mmu implementation sets the bit even when the
-access is aborted.
-
-This is the reason why test 064 of the `ekbee1` diagnostics currently fails.
-
-Since the MMU trap mechanism is is only available on 11/45 and 11/70, but
-not in the J11, it is not used by common operating systems.
-
-Therefore this is considered a to be a minor deficit. Will be fixed in an
-upcoming release.
-
-### V0.50-5 {[issue #25](https://github.com/wfjm/w11/issues/25)} -- CPU: The AIB bit in MMU PDR register set independant of ACF field
-
-The MMU should set the AIB A bit in the the PDR only when _"trap condition is
-met by the Access Control Field (ACF)"_. Thus for
-```
-   ACF=001 read-only  trap on read
-   ACF=100 read/write trap on read or write
-   ACF=101 read/write trap on write
-```
-The current pdp11_mmu implementation always sets the bit, the logic is simply
-```
-    if doabort = '0' then
-      AIB_SETA <= '1';
-      AIB_SETW <= CNTL.wacc or CNTL.macc;
-    end if;
-```
-
-Since the MMU trap mechanism is is only available on 11/45 and 11/70, but not
-in the J11, it is not used by common operating systems.
-
-Therefore this is considered a to be a minor deficit. Will be fixed in an
-upcoming release.
-
 ### V0.50-1 {[issue #23](https://github.com/wfjm/w11/issues/23)} -- CPU: several deficits in trap logic
 
 The current w11a implementation has several deficits in the handling of
@@ -250,212 +158,3 @@ _{the last two issues are not relevant for w11 backend over USB usage because
 the backend produces proper command lists and the USB channel is usually error
 free}_
 
-## Resolved Issues
-
-### V0.50-4 {[issue #24](https://github.com/wfjm/w11/issues/24)} -- CPU: src+dst deltas summed in mmr1 if register identical
-
-Test 12 of maindec `ekbee1` fails because it expects after a
-```
-        mov    #100000,@#mmr0
-```
-which sets an error bit in `mmr0` and thus freezes `mmr0`, that `mmr1` contains
-```
-  013427 (00010 111 00010 111) (+2,r7;+2,r7)
-```
-while w11a gives
-```
-  000047 (00000 000 00100 111) (--,--;+4,r7)
-```
-The `mmr1` content is _different_ compared to the original 11/70 behavior,
-but is _logically correct_, fault recovery in OS (like in 211bsd) will work
-correctly.  Therefore this is considered a to be a _minor deficit_.
-
-The 11/70 documentation clearly states that there is an additional state bit
-that counts the write accesses to `mmr1`. This ensures that each of the two
-logged accesses end in separate bytes (byte 0 filled first).
-
-The w11a only uses byte 1 when the register number differs.
-
-Fixed with commit [3bd23c9](https://github.com/wfjm/w11/commit/3bd23c9),
-see [ECO-032](ECO-032-MMR1_fix.md).
-
-### V0.79-1 {[issue #29](https://github.com/wfjm/w11/issues/29)} -- migrate from Travis to GitHub actions
-
-#### Original Issue
-Travis is now defunct and has been removed in
-[6b8c063](https://github.com/wfjm/w11/commit/6b8c063).
-So it's time to migrate CI/CD to GitHub actions.
-
-#### Fix
-GitHub Actions fully implemented with commit
-[db7556a4](https://github.com/wfjm/w11/commit/db7556a4), fine tuned with commit
-[66f3f5d0](https://github.com/wfjm/w11/commit/66f3f5d0).
-
-### V0.76-1 {[issue #16](https://github.com/wfjm/w11/issues/16)} -- Help wanted: Testing with Nexys4 DDR appreciated
-#### Original Issue
-The w11a design for Nexys4 DDR, see
-[rtl/sys_gen/w11a/nexys4d](https://github.com/wfjm/w11/tree/master/rtl/sys_gen/w11a/nexys4d),
-was provided to support also an up-to-date Nexys4 board. It is so far only
-simulation tested.
-
-Testing done with a real Nexyx4 DDR, or a newer Nexys A7-100T, would be highly
-appreciated. Please double check the pin assignments
-(see _mig_a.prj and nexys4d*.xdc_) with the documentation of your board
-to avoid potential damage.
-
-Looking forward to receive test reports.
-
-#### Fix
-The Nexys4 _(classic, with 16 MByte PSRAM)_ board, on which most of the recent
-w11 was done, broke in late July 2019
-(see [blog](https://wfjm.github.io/blogs/w11/2019-07-27-nexys4-obituary.html))
-and a Nexys A7 was ordered as replacement.
-
-Basic tests with the test designs
-[sys_tst_serloop2](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/tst_serloop/nexys4d/sys_tst_serloop2_n4d.vhd) and
-[sys_tst_rlink_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/tst_rlink/nexys4d/sys_tst_rlink_n4d.vhd)
-and the BRAM-only w11 design
-[sys_w11a_br_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/w11a/nexys4d_bram/sys_w11a_br_n4d.vhd) worked fine.
-
-But all tests involving the DDR2 memory interface failed. The culprit was
-quickly found, it was a mistake in the MIG configuration
-[mig_a.prj](https://github.com/wfjm/w11/blob/master/rtl/bplib/nexys4d/mig_a.prj),
-the polarity of the `SYS_RST` signal was `ACTIVE LOW` instead of `ACTIVE HIGH`.
-After fixing this, the test designs
-[sys_tst_mig_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/tst_mig/nexys4d/sys_tst_mig_n4d.vhd) and
-[sys_tst_sram_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/tst_sram/nexys4d/sys_tst_sram_n4d.vhd)
-as well as the w11 implementation
-[sys_w11a_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/w11a/nexys4d/sys_w11a_n4d.vhd) worked right away.
-
-The [tst_sram](https://github.com/wfjm/w11/tree/master/rtl/sys_gen/tst_sram)
-designs show nicely that the DDR2 on the Nexys A7 board is slightly slower
-than the DDR3 on the Arty A7 board
-```
-   Board     test time   clock period     UI_CLK
-  Nexys A7     37.36 s        3333 ps   75.0 MHz 
-  Arty A7      35.77 s        3000 ps   83.3 MHz
-```
-
-Closed with commit
-[563e230](https://github.com/wfjm/w11/commit/563e230).
-
-### V0.66-1 {[issue #8](https://github.com/wfjm/w11/issues/8)} -- TM11 controller doesn't support odd transfer size
-#### Original Issue
-The TM11 controller transfers data byte wise (all disk do it 16bit 
-word wise) and allows for odd byte length transfers. Odd length transfers
-are currently not supported and rejected as invalid command. Odd byte 
-length records aren't used by OS, so in practice this limitation 
-isn't relevant.
-#### Fix
-Odd record length support added with commit
-[5b52e54](https://github.com/wfjm/w11/commit/5b52e54).
-
-### V0.742-1 {[issue #14](https://github.com/wfjm/w11/issues/14)} -- SEGFAULT core dump after detach
-#### Original Issue
-The detach of a `tcp` type virtual terminal or a `tap` type virtual
-ethernet device can lead to a SEGFAULT core dump, e.g. after a
-`cpu0ttb0 det` command.
-This is caused by a race condition between the detach run-down and the
-implementation of `ReventLoop::RemovePollHandler()`.
-#### Fix
-The culprit was a design error in the `RemovePollHandler` flow, which
-allowed that `DoPoll` returned while poll list updates were still pending
-and the subsequent execution of `DoCall` called removed handlers.
-`DoPoll` now loops until there are no pending poll list updates and
-`DoCall` quits processing poll change notifications when it detects
-pending poll list updates.
-
-Fixed with commit [6f56f29](https://github.com/wfjm/w11/commit/6f56f29).
-
-### V0.64-1 {[issue #3](https://github.com/wfjm/w11/issues/3)} -- Bad throughput for DL11 emulation for low speed links
-#### Original Issue
-The large default transfer size for disk accesses leads to bad
-throughput in the DL11 emulation for low speed links, like the
-460kBaud the S3board is limited to. Will be overcome by a DL11
-controller with more buffering.
-#### Fix
-Fixed Resolved with buffered DL11 in commit
-[1c9dbeb](https://github.com/wfjm/w11/commit/1c9dbeb).
-
-### V0.50-10 {[issue #20](https://github.com/wfjm/w11/issues/20)} -- DL11: output chars lost when device polling used
-#### Original Issue
-Part of the console output can be lost when `xxdp` test `eqkce1` is
-run on FPGA, also some kernel messages during the 2.11bsd boot sequence.
-In both cases very simple polling output routines are used. Most likely
-cause is that device ready polls timeout before the rlink interface can
-serve the output request.
-#### Fix
-Is overcome with buffered DL11 controller with much higher throughput and
-improved interrupt rate control.
-
-Fixed with commit [1c9dbeb](https://github.com/wfjm/w11/commit/1c9dbeb).
-
-### V0.77-1 {[issue #19](https://github.com/wfjm/w11/issues/19)} -- tcl getters accessing a const reference crash with a SIGSEGV
-#### Original Issue
-tcl commands like
-```
-  cpu0 get type
-  cpu0rka get class
-  rlc get timeout
-```
-crash with a `SIGSEGV`. Apparently all getters which internally return a
-const reference are affected. Observed with gcc 5.4.0. Unclear whether this
-is a coding bug introduced when `boost::bind` was replaced by lambdas
-(in commit [1620ee3](https://github.com/wfjm/w11/commit/1620ee3)) or a
-compiler issue.
-#### Fix
-The culprit was that automatic return type determination for the getter
-lambdas was used. This fails when the called method returns a reference of
-an object. The deduced lambda return type will the object, not a reference.
-Unfortunately this doesn't lead to a compile time error but to a run time error.
-
-Bottom lime is
-- automatic return type detection for lambda's can be error prone
-- it is safer and also more compact to use `std:bind` as method forwarder
-
-Fixed with commit [6024dce](https://github.com/wfjm/w11/commit/6024dce).
-
-### V0.73-3 {[issue #11](https://github.com/wfjm/w11/issues/11)} -- dmscnt and dmcmon disabled in Vivado based flows
-#### Original Issue
-The 'state number generator' code in `pdp11_sequencer` causes in Vivado
-2016.1 (and .2) that the main FSM isn't re-coded anymore, which has high 
-impact on achievable clock rate. The two optional debug units depending on 
-the state number, `dmscnt` and `dmcmon`, are therefore currently deactivated in
-all Artix based systems (but are available on all Spartan based systems).
-#### Fix
-At least mitigated with [d14626c](https://github.com/wfjm/w11/commit/d14626c)
-which allows to use `dmcmon` without the full state number generation logic
-in `pdp11_sequencer`. Reintroduced `dmcmon` in `sys_w11a_n4` again. `dmscnt` is
-still deconfigured for Vivado designs, but this has much less practical impact.
-
-## Closed issues
-
-### V0.73-1 {[issue #9](https://github.com/wfjm/w11/issues/9)} -- Vivado xelab sometimes extremely slow
-#### Original Issue
-as of Vivado 2016.2 `xelab` shows sometimes extremely long build times,
-especially for generated post-synthesis VHDL models. But also building a
-behavioral simulation for a w11a design can take 25 min. Even though
-post-synthesis or post-routing models are now generated in Verilog working
-with `xsim` is cumbersome and time consuming.
-
-#### Reason for closure on 2022-07-05
-Re-checked with Vivado 2022.1.
-Building models with `xelab` is now quite fast.
-The issue disappeared somewhere between Vivado 2016.3 and 2022.1.
-
-### V0.76-2 {[issue #17](https://github.com/wfjm/w11/issues/17)} -- Help wanted: Testing with Arty S7 appreciated
-#### Original Issue
-The w11a design for Arty S7 (50 die size), see rtl/sys_gen/w11a/artys7,
-was provided to support also an up-to-date Spartan-7 based board. Turned
-out that speed is equivalent to Artix-7. It is so far only simulation tested.
-
-Testing done with a real Arty S7, would be highly appreciated. Please double
-check the pin assignments (see _mig_a.prj and artys7*.xdc_) with the
-documentation of your board to avoid potential damage.
-
-Looking forward to receive test reports.
-
-#### Reason for closure on 2020-04-20
-Apparently nobody invested into an Arty S7.
-The sys_w11a_as7 will be marked untested, removed from the default build
-and test flows, but kept in the repository.
diff --git a/doc/README_resolved_issues.md b/doc/README_resolved_issues.md
new file mode 100644
index 00000000..5bbd4852
--- /dev/null
+++ b/doc/README_resolved_issues.md
@@ -0,0 +1,316 @@
+# Resolved issues
+
+### V0.791-2 {[issue #34](https://github.com/wfjm/w11/issues/34)} -- MMU: ACF=1 traps on any access
+
+Test 055 of `ekbee1` fails with
+```
+    MEMORY MANAGEMENT TRAP OR ABORT HAD INCORRECT CONDITION
+    EXPECTD ERROR   AUTOI/D VIRTUAL
+    CONDITN REGISTR REGISTR ADDRESS TESTNO  PC AT ABORT
+    020011  030011  013427  054032  000055  054040
+```
+This is caused by a bug in pdp11_mmu. For ACF=1 a trap is taken for any access,
+it should be taken only for read accesses.
+
+Fixed with commit [1644863](https://github.com/wfjm/w11/commit/1644863),
+see [ECO-033](ECO-033-MMU_AFC-1_PDR-A.md).
+
+### V0.791-1 {[issue #33](https://github.com/wfjm/w11/issues/33)} -- MMU: PDR A bit is set for every access
+
+The `PDR` `A` bit is described in the Technical Manual as
+>  A bit (bit 7) - This bit is used by software to determine whether or not  
+>  any accesses to this page met the trap condition specified by the Access  
+>  Control Field (ACF). (A = I is affirmative). The A bit is used in the  
+>  process of gathering Memory Management statistics.
+
+It is set when the page `ACF` enables an MMU trap, thus for
+-  ACF=1 and read access
+-  ACF=4 and any access
+-  ACF=5 and write access
+
+The w11 currently sets the 'A' bit on any non-aborted access regardless of the ACF value.
+
+No practical impact, the 'A' bit in `PDR` is a 11/45 11/70 only feature and not used in OS software.
+
+Fixed with commit [1644863](https://github.com/wfjm/w11/commit/1644863),
+see [ECO-033](ECO-033-MMU_AFC-1_PDR-A.md).
+
+### V0.50-6 {[issue #26](https://github.com/wfjm/w11/issues/26)} -- CPU: MMR0 trap bit set when access aborted
+
+The MMU should set the 'trap bit' in `MMR0` only when the access is not
+aborted. The current pdp11_mmu implementation sets the bit even when the
+access is aborted.
+
+This is the reason why test 064 of the `ekbee1` diagnostics currently fails.
+
+Since the MMU trap mechanism is is only available on 11/45 and 11/70, but
+not in the J11, it is not used by common operating systems.
+
+Therefore this is considered a to be a minor deficit. Will be fixed in an
+upcoming release.
+
+Fixed with commit [1644863](https://github.com/wfjm/w11/commit/1644863),
+see [ECO-033](ECO-033-MMU_AFC-1_PDR-A.md).
+
+### V0.50-5 {[issue #25](https://github.com/wfjm/w11/issues/25)} -- CPU: The AIB bit in MMU PDR register set independant of ACF field
+
+The MMU should set the AIB A bit in the the PDR only when _"trap condition is
+met by the Access Control Field (ACF)"_. Thus for
+```
+   ACF=001 read-only  trap on read
+   ACF=100 read/write trap on read or write
+   ACF=101 read/write trap on write
+```
+The current pdp11_mmu implementation always sets the bit, the logic is simply
+```
+    if doabort = '0' then
+      AIB_SETA <= '1';
+      AIB_SETW <= CNTL.wacc or CNTL.macc;
+    end if;
+```
+
+Since the MMU trap mechanism is is only available on 11/45 and 11/70, but not
+in the J11, it is not used by common operating systems.
+
+Therefore this is considered a to be a minor deficit. Will be fixed in an
+upcoming release.
+
+Fixed with commit [1644863](https://github.com/wfjm/w11/commit/1644863),
+see [ECO-033](ECO-033-MMU_AFC-1_PDR-A.md).
+
+### V0.79-2 {[issue #30](https://github.com/wfjm/w11/issues/30)} -- SimH scmd files fail on current 4.* version; only 3.* supported
+
+The SimH scmd scripts were originally developed for SimH 3.8, and worked for
+SimH 3.9 and later releases. The SimH 4.* development team decided not to
+provide releases anymore, and over time this version became incompatible with
+the scmd scripts used for w11. That is most pronounced for the RT11 V4.3 oskit.
+A simple
+```
+  cd $RETROBASE/tools/oskit/rt11-53_rl
+  console_starter -s -d DL0  &
+  pdp11 rt11-53_rl_boot.scmd
+```
+works fine for SimH V3.9, V3.10 and V3.11-1, but fails
+- for pdp11-4.0-beta1 with core dump
+- for pdp11-2016-12-26-5ced037b with signal SIGSEGV in pdp11_xu
+- for pdp11-2019-07-28-2f707ffc with signal SIGSEGV in pdp11_xu
+- for pdp11-2020-03-26-261abfc3 with signal SIGSEGV in pdp11_xu
+- for pdp11-2021-08-22-64b12234 with signal SIGSEGV in pdp11_xu
+- for pdp11-2022-04-17-d3f1ee09 with with errors like
+  - Device auto configuration is now disabled
+  - Command not allowed (for set rha enabled)
+  - container incompatible with the RL device
+
+Bottom line:
+- the provided scmd scripts work only with SimH V3.9, V3.10 or V3.11-1
+- an update to the SimH V4.* has low priority
+
+Fixed with commit [35453c4](https://github.com/wfjm/w11/commit/35453c4)
+
+### V0.50-4 {[issue #24](https://github.com/wfjm/w11/issues/24)} -- CPU: src+dst deltas summed in mmr1 if register identical
+
+Test 12 of maindec `ekbee1` fails because it expects after a
+```
+        mov    #100000,@#mmr0
+```
+which sets an error bit in `mmr0` and thus freezes `mmr0`, that `mmr1` contains
+```
+  013427 (00010 111 00010 111) (+2,r7;+2,r7)
+```
+while w11a gives
+```
+  000047 (00000 000 00100 111) (--,--;+4,r7)
+```
+The `mmr1` content is _different_ compared to the original 11/70 behavior,
+but is _logically correct_, fault recovery in OS (like in 211bsd) will work
+correctly.  Therefore this is considered a to be a _minor deficit_.
+
+The 11/70 documentation clearly states that there is an additional state bit
+that counts the write accesses to `mmr1`. This ensures that each of the two
+logged accesses end in separate bytes (byte 0 filled first).
+
+The w11a only uses byte 1 when the register number differs.
+
+Fixed with commit [3bd23c9](https://github.com/wfjm/w11/commit/3bd23c9),
+see [ECO-032](ECO-032-MMR1_fix.md).
+
+### V0.79-1 {[issue #29](https://github.com/wfjm/w11/issues/29)} -- migrate from Travis to GitHub actions
+
+#### Original Issue
+Travis is now defunct and has been removed in
+[6b8c063](https://github.com/wfjm/w11/commit/6b8c063).
+So it's time to migrate CI/CD to GitHub actions.
+
+#### Fix
+GitHub Actions fully implemented with commit
+[db7556a4](https://github.com/wfjm/w11/commit/db7556a4), fine tuned with commit
+[66f3f5d0](https://github.com/wfjm/w11/commit/66f3f5d0).
+
+### V0.76-1 {[issue #16](https://github.com/wfjm/w11/issues/16)} -- Help wanted: Testing with Nexys4 DDR appreciated
+#### Original Issue
+The w11a design for Nexys4 DDR, see
+[rtl/sys_gen/w11a/nexys4d](https://github.com/wfjm/w11/tree/master/rtl/sys_gen/w11a/nexys4d),
+was provided to support also an up-to-date Nexys4 board. It is so far only
+simulation tested.
+
+Testing done with a real Nexyx4 DDR, or a newer Nexys A7-100T, would be highly
+appreciated. Please double check the pin assignments
+(see _mig_a.prj and nexys4d*.xdc_) with the documentation of your board
+to avoid potential damage.
+
+Looking forward to receive test reports.
+
+#### Fix
+The Nexys4 _(classic, with 16 MByte PSRAM)_ board, on which most of the recent
+w11 was done, broke in late July 2019
+(see [blog](https://wfjm.github.io/blogs/w11/2019-07-27-nexys4-obituary.html))
+and a Nexys A7 was ordered as replacement.
+
+Basic tests with the test designs
+[sys_tst_serloop2](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/tst_serloop/nexys4d/sys_tst_serloop2_n4d.vhd) and
+[sys_tst_rlink_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/tst_rlink/nexys4d/sys_tst_rlink_n4d.vhd)
+and the BRAM-only w11 design
+[sys_w11a_br_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/w11a/nexys4d_bram/sys_w11a_br_n4d.vhd) worked fine.
+
+But all tests involving the DDR2 memory interface failed. The culprit was
+quickly found, it was a mistake in the MIG configuration
+[mig_a.prj](https://github.com/wfjm/w11/blob/master/rtl/bplib/nexys4d/mig_a.prj),
+the polarity of the `SYS_RST` signal was `ACTIVE LOW` instead of `ACTIVE HIGH`.
+After fixing this, the test designs
+[sys_tst_mig_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/tst_mig/nexys4d/sys_tst_mig_n4d.vhd) and
+[sys_tst_sram_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/tst_sram/nexys4d/sys_tst_sram_n4d.vhd)
+as well as the w11 implementation
+[sys_w11a_n4d](https://github.com/wfjm/w11/blob/master/rtl/sys_gen/w11a/nexys4d/sys_w11a_n4d.vhd) worked right away.
+
+The [tst_sram](https://github.com/wfjm/w11/tree/master/rtl/sys_gen/tst_sram)
+designs show nicely that the DDR2 on the Nexys A7 board is slightly slower
+than the DDR3 on the Arty A7 board
+```
+   Board     test time   clock period     UI_CLK
+  Nexys A7     37.36 s        3333 ps   75.0 MHz 
+  Arty A7      35.77 s        3000 ps   83.3 MHz
+```
+
+Closed with commit
+[563e230](https://github.com/wfjm/w11/commit/563e230).
+
+### V0.66-1 {[issue #8](https://github.com/wfjm/w11/issues/8)} -- TM11 controller doesn't support odd transfer size
+#### Original Issue
+The TM11 controller transfers data byte wise (all disk do it 16bit 
+word wise) and allows for odd byte length transfers. Odd length transfers
+are currently not supported and rejected as invalid command. Odd byte 
+length records aren't used by OS, so in practice this limitation 
+isn't relevant.
+#### Fix
+Odd record length support added with commit
+[5b52e54](https://github.com/wfjm/w11/commit/5b52e54).
+
+### V0.742-1 {[issue #14](https://github.com/wfjm/w11/issues/14)} -- SEGFAULT core dump after detach
+#### Original Issue
+The detach of a `tcp` type virtual terminal or a `tap` type virtual
+ethernet device can lead to a SEGFAULT core dump, e.g. after a
+`cpu0ttb0 det` command.
+This is caused by a race condition between the detach run-down and the
+implementation of `ReventLoop::RemovePollHandler()`.
+#### Fix
+The culprit was a design error in the `RemovePollHandler` flow, which
+allowed that `DoPoll` returned while poll list updates were still pending
+and the subsequent execution of `DoCall` called removed handlers.
+`DoPoll` now loops until there are no pending poll list updates and
+`DoCall` quits processing poll change notifications when it detects
+pending poll list updates.
+
+Fixed with commit [6f56f29](https://github.com/wfjm/w11/commit/6f56f29).
+
+### V0.64-1 {[issue #3](https://github.com/wfjm/w11/issues/3)} -- Bad throughput for DL11 emulation for low speed links
+#### Original Issue
+The large default transfer size for disk accesses leads to bad
+throughput in the DL11 emulation for low speed links, like the
+460kBaud the S3board is limited to. Will be overcome by a DL11
+controller with more buffering.
+#### Fix
+Fixed Resolved with buffered DL11 in commit
+[1c9dbeb](https://github.com/wfjm/w11/commit/1c9dbeb).
+
+### V0.50-10 {[issue #20](https://github.com/wfjm/w11/issues/20)} -- DL11: output chars lost when device polling used
+#### Original Issue
+Part of the console output can be lost when `xxdp` test `eqkce1` is
+run on FPGA, also some kernel messages during the 2.11bsd boot sequence.
+In both cases very simple polling output routines are used. Most likely
+cause is that device ready polls timeout before the rlink interface can
+serve the output request.
+#### Fix
+Is overcome with buffered DL11 controller with much higher throughput and
+improved interrupt rate control.
+
+Fixed with commit [1c9dbeb](https://github.com/wfjm/w11/commit/1c9dbeb).
+
+### V0.77-1 {[issue #19](https://github.com/wfjm/w11/issues/19)} -- tcl getters accessing a const reference crash with a SIGSEGV
+#### Original Issue
+tcl commands like
+```
+  cpu0 get type
+  cpu0rka get class
+  rlc get timeout
+```
+crash with a `SIGSEGV`. Apparently all getters which internally return a
+const reference are affected. Observed with gcc 5.4.0. Unclear whether this
+is a coding bug introduced when `boost::bind` was replaced by lambdas
+(in commit [1620ee3](https://github.com/wfjm/w11/commit/1620ee3)) or a
+compiler issue.
+#### Fix
+The culprit was that automatic return type determination for the getter
+lambdas was used. This fails when the called method returns a reference of
+an object. The deduced lambda return type will the object, not a reference.
+Unfortunately this doesn't lead to a compile time error but to a run time error.
+
+Bottom lime is
+- automatic return type detection for lambda's can be error prone
+- it is safer and also more compact to use `std:bind` as method forwarder
+
+Fixed with commit [6024dce](https://github.com/wfjm/w11/commit/6024dce).
+
+### V0.73-3 {[issue #11](https://github.com/wfjm/w11/issues/11)} -- dmscnt and dmcmon disabled in Vivado based flows
+#### Original Issue
+The 'state number generator' code in `pdp11_sequencer` causes in Vivado
+2016.1 (and .2) that the main FSM isn't re-coded anymore, which has high 
+impact on achievable clock rate. The two optional debug units depending on 
+the state number, `dmscnt` and `dmcmon`, are therefore currently deactivated in
+all Artix based systems (but are available on all Spartan based systems).
+#### Fix
+At least mitigated with [d14626c](https://github.com/wfjm/w11/commit/d14626c)
+which allows to use `dmcmon` without the full state number generation logic
+in `pdp11_sequencer`. Reintroduced `dmcmon` in `sys_w11a_n4` again. `dmscnt` is
+still deconfigured for Vivado designs, but this has much less practical impact.
+
+## Closed issues
+
+### V0.73-1 {[issue #9](https://github.com/wfjm/w11/issues/9)} -- Vivado xelab sometimes extremely slow
+#### Original Issue
+as of Vivado 2016.2 `xelab` shows sometimes extremely long build times,
+especially for generated post-synthesis VHDL models. But also building a
+behavioral simulation for a w11a design can take 25 min. Even though
+post-synthesis or post-routing models are now generated in Verilog working
+with `xsim` is cumbersome and time consuming.
+
+#### Reason for closure on 2022-07-05
+Re-checked with Vivado 2022.1.
+Building models with `xelab` is now quite fast.
+The issue disappeared somewhere between Vivado 2016.3 and 2022.1.
+
+### V0.76-2 {[issue #17](https://github.com/wfjm/w11/issues/17)} -- Help wanted: Testing with Arty S7 appreciated
+#### Original Issue
+The w11a design for Arty S7 (50 die size), see rtl/sys_gen/w11a/artys7,
+was provided to support also an up-to-date Spartan-7 based board. Turned
+out that speed is equivalent to Artix-7. It is so far only simulation tested.
+
+Testing done with a real Arty S7, would be highly appreciated. Please double
+check the pin assignments (see _mig_a.prj and artys7*.xdc_) with the
+documentation of your board to avoid potential damage.
+
+Looking forward to receive test reports.
+
+#### Reason for closure on 2020-04-20
+Apparently nobody invested into an Arty S7.
+The sys_w11a_as7 will be marked untested, removed from the default build
+and test flows, but kept in the repository.