Zap bug?

I’ve been using Zap (1.49 13-Jun-20 rick-07) for a while now and no issues. However I changed the order in which I opened a number of programs and I encounter a crash with Zap. I’m running RISC OS 5.29 (15-Dec-20) so it could be related to that. Machine RPi4.

The issue for me is repeatable. I open an Obey file to open a taskwindow and I then go into a .c directory and open a file called main. I get a crash and Zap opens not the program file, but another taskwindow. It might sound daft, but if I change the order or open other programs or a file the issue isn’t present.

excdump

Error block: 80000001 Internal error: abort on instruction fetch at &00000000
R0 = 0002acc4
R1 = 00000000
R2 = 00000000
R3 = 0003425c
R4 = 02051008
R5 = 00035e8c
R6 = 0003411c
R7 = 00035e8c
R8 = 0002ba28
R9 = 0002bd64
R10 = 00036061
R11 = 00000000
R12 = 20365db4
R13 = 000086cc
R14 = 2040745c
R15 = 00000004
CPSR = 40000110
R13_usr = 000086cc
R14_usr = 2040745c
R13_svc = fa208000
R14_svc = 20371590
SPSR_svc = 80000110
R13_irq = fa102000
R14_irq = 40000113
SPSR_irq = 40000113
R13_abt = fa301fa8
R14_abt = 00000004
SPSR_abt = 40000110
R13_und = fa402000
R14_und = fc166780
SPSR_und = 60000113
OSMem16: 2 = fa100000, 00002000, 00002000
OSMem16: 3 = fa200000, 00008000, 00008000
OSMem16: 4 = fa300000, 00002000, 00002000
OSMem16: 5 = fa400000, 00002000, 00002000
Memory: fa100000 - fa102000
Memory: fa200000 - fa208000
Memory: fa300000 - fa302000
Memory: fa400000 - fa402000
Memory: ffff0108 - ffff010c
OSRSI6: 69 = ffff0108

R15 = 00000004 is system workspace
R14_usr = 2040745c = ZapMJE +2bc8

USR stack:
000086cc : 00000000 :
000086d0 : 0003411c :
000086d4 : 20372410 : - Return to 20372410?
         :          : | = Zap +19bc
         :          : | = redraw_cache_line +80
000086d8 : 00000148 : - R2
000086dc : 00000001 : | R3
000086e0 : 00000001 : | R4
000086e4 : ffffffff : | R5
000086e8 : 00034114 : | R6
000086ec : 00000000 : | R10
000086f0 : 20372184 : | R14: 20372184 (ASM call to 20372390)
         :          : | 20372184 = Zap +1730
         :          : | = red_cache_lines +84
         :          : | 20372390 = Zap +193c
         :          : | = redraw_cache_line +0
000086f4 : 00000000 :
000086f8 : 00000000 :
000086fc : 00000000 : - R2
00008700 : 00000001 : | R3
00008704 : 00000000 : | R4
00008708 : 00000000 : | R5
0000870c : 2037201c : | R14: 2037201c (ASM call to 20372100)
         :          : | 2037201c = Zap +15c8
         :          : | = update_cache +13c
         :          : | 20372100 = Zap +16ac
         :          : | = red_cache_lines +0
00008710 : 20365e0c :                                            - R1
00008714 : 00000000 :                                            | R2
00008718 : 00000001 :                                            | R3
0000871c : 00000000 :                                            | R4
00008720 : 00000000 :                                            | R5
00008724 : 00015a2c :                                            | R6
00008728 : 0000c220 :                                            | R7
0000872c : 0002ba28 :                                            | R8
00008730 : 0002bd64 :                                            | R9
00008734 : 00009498 :                                            | R10
00008738 : 20409160 : - Return to 20409160?                      | R11
         :          : | = ZapMJE +48cc                           | 
0000873c : 20371350 :                                            | R14: 20371350 (ASM call to 20371ee0)
         :          :                                            | 20371350 = Zap +8fc
         :          :                                            | = redraw_window +c
         :          :                                            | 20371ee0 = Zap +148c
         :          :                                            | = update_cache +0
00008740 : 00009108 : - R1
00008744 : 00000010 : | R2
00008748 : ffffffde : | R3
0000874c : 00000000 : | R4
00008750 : 20372a0c : | R14: 20372a0c (ASM call to 20371344)
         :          : | 20372a0c = Zap +1fb8
         :          : | = update_window +14
         :          : | 20371344 = Zap +8f0
         :          : | = redraw_window +0
00008754 : 00009108 : - R1
00008758 : 203729dc : | R14: 203729dc (ASM call to 203729f8)
         :          : | 203729dc = Zap +1f88
         :          : | = update_area +4c
         :          : | 203729f8 = Zap +1fa4
         :          : | = update_window +0
0000875c : 00009108 : - R1
00008760 : 00000000 : | R2
00008764 : 00000558 : | R3
00008768 : 00000004 : | R4
0000876c : 20377e64 : | R14: 20377e64 (ASM call to 20372990)
         :          : | 20377e64 = Zap +7410
         :          : | = clear_caret +64
         :          : | 20372990 = Zap +1f3c
         :          : | = update_area +0
00008770 : 00000000 :
00008774 : 0002ba28 :
00008778 : 0002bd64 :
0000877c : 203781dc : - 20377e00 return to 203781dc?
         :          : | 20377e00 = Zap +73ac
         :          : | = clear_caret +0
         :          : | 203781dc = Zap +7788
         :          : | = null_caret +1c
00008780 : 203780e8 : - R14: 203780e8 (ASM call to 203781c0)
         :          : | 203780e8 = Zap +7694
         :          : | = set_caret_mode_from1 +34
         :          : | 203781c0 = Zap +776c
         :          : | = null_caret +0
00008784 : 00000000 :                                            - R1
00008788 : 00000000 :                                            | R2
0000878c : 00000558 :                                            | R3
00008790 : 00000004 :                                            | R4
00008794 : 00000000 :                                            | R5
00008798 : 00015a2c :                                            | R6
0000879c : 0000c220 :                                            | R7
000087a0 : 0002ba28 :                                            | R8
000087a4 : 0002bd64 :                                            | R9
000087a8 : 00009498 :                                            | R10
000087ac : 20409160 : - Return to 20409160?                      | R11
         :          : | = ZapMJE +48cc                           | 
000087b0 : 20377fc4 :                                            | R14: 20377fc4 (ASM call to 203780b4)
         :          :                                            | 20377fc4 = Zap +7570
         :          :                                            | = set_caret_mode +34
         :          :                                            | 203780b4 = Zap +7660
         :          :                                            | = set_caret_mode_from1 +0
000087b4 : 00000004 : - R1
000087b8 : 203783dc : | R14: 203783dc (ASM call to 20377f90)
         :          : | 203783dc = Zap +7988
         :          : | = delete_carets +38
         :          : | 20377f90 = Zap +753c
         :          : | = set_caret_mode +0
000087bc : 20397888 : - R10
000087c0 : 2037b054 : | R14: 2037b054 (ASM call to 203783a4)
         :          : | 2037b054 = Zap +a600
         :          : | = discard_window +84
         :          : | 203783a4 = Zap +7950
         :          : | = delete_carets +0
000087c4 : 00000003 :
000087c8 : 2037c1a4 : - Return to 2037c1a4?
         :          : | = Zap +b750
         :          : | = do_eachwindow +50
000087cc : 00000000 : - R8
000087d0 : 00000000 : | R11
000087d4 : 2039786c : | R14: 2039786c (ASM call to 2037c154)
         :          : | 2039786c = Zap +26e18
         :          : | = discard_file +84
         :          : | 2037c154 = Zap +b700
         :          : | = do_eachwindow +0
000087d8 : 00000000 :
000087dc : 203977ec :
000087e0 : 00000000 :
000087e4 : 20394da0 : - Return to 20394da0?
         :          : | = Zap +2434c
         :          : | = do_allfiles +34
000087e8 : 00000000 : - R9
000087ec : 00008808 : | R11
000087f0 : 2039899c : | R14: 2039899c (ASM call to 20394d6c)
         :          : | 2039899c = Zap +27f48
         :          : | = dump_file +170
         :          : | 20394d6c = Zap +24318
         :          : | = do_allfiles +0
000087f4 : 20371344 : - R10
000087f8 : 2039f528 : | R14: 2039f528 (ASM call to 2039898c)
         :          : | 2039f528 = Zap +2ead4
         :          : | = clean_up +1c
         :          : | 2039898c = Zap +27f38
         :          : | = dump_file +160
000087fc : 203a9040 : - R14: 203a9040 (ASM call to 2039f50c)
         :          : | 203a9040 = Zap +385ec
         :          : | = ExitHandler +14
         :          : | 2039f50c = Zap +2eab8
         :          : | = clean_up +0
00008800 : 0070615a :
00008804 : e3a02001 :
00008808 : 00000018 :
0000880c : 69403984 :
00008810 : 00000722 :
00008814 : 00000000 :
00008818 : 00000008 :
0000881c : 00000000 :
00008820 : 000a0000 :
00008824 : ffffffff :
00008828 : 00000302 :
0000882c : 00000934 :
00008830 : 000008a2 :
00008834 : 49534353 :
00008838 : 61483a3a :
0000883c : 69446472 :
00008840 : 2e306373 :
00008844 : 6f432e24 :
00008848 : 502e6564 :
0000884c : 74636172 :
00008850 : 2e656369 :
00008854 : 6c6f6f54 :
00008858 : 2e786f42 :
0000885c : 616d2e63 :
00008860 : 3b006e69 :
00008864 : 6172436d :
00008868 : 20006873 :
0000886c : 00000000 :
00008870 : 00000001 :
00008874 : 20005050 :
00008878 : 00000000 :
0000887c : 00000000 :
00008880 : 00000000 :
00008884 : 00000000 :
00008888 : 00000000 :
0000888c : 00000000 :
00008890 : 00000000 :
00008894 : 00000000 :
00008898 : 00000000 :
0000889c : 00000000 :
000088a0 : 00000000 :
000088a4 : 00000000 :
000088a8 : 00000000 :
000088ac : 00000000 :
000088b0 : 00000000 :
000088b4 : 00000000 :
000088b8 : 00000000 :
000088bc : 00000000 :
000088c0 : 00000000 :
000088c4 : 00000000 :
000088c8 : 00000000 :
000088cc : 00000000 :
000088d0 : 00000000 :
000088d4 : 00000000 :
000088d8 : 00000000 :
000088dc : 00000000 :
000088e0 : 00000000 :
000088e4 : 00000000 :
000088e8 : 00000000 :
000088ec : 00000000 :
000088f0 : 00000000 :
000088f4 : 00000000 :
000088f8 : 00000000 :
000088fc : 00000000 :
00008900 : 00000000 :
00008904 : 00000000 :
00008908 : 202bd0d9 :
0000890c : ffffffff :
00008910 : 00000000 :
00008914 : 00000000 :
00008918 : 02000000 :
0000891c : ffffffff :
00008920 : 000001fc :
00008924 : ffffffff :
00008928 : ff000102 :
0000892c : ff070207 :
00008930 : 000c0103 :
00008934 : fffffffc :
00008938 : fffff4c0 :
0000893c : 000004d4 :
00008940 : 00000000 :
00008944 : 0000013d :
00008948 : 203d16b9 :
0000894c : 0000045c :
00008950 : 00000302 :
00008954 : 00000934 :
00008958 : 000008a2 :
0000895c : fffffffc :
00008960 : 00000000 :
00008964 : ffffffff :
00008968 : ff130102 :
0000896c : 00000000 :
00008970 : 00000000 :
00008974 : 00000000 :
00008978 : 00000000 :
0000897c : 00000000 :
00008980 : 00000000 :
00008984 : 00000000 :
00008988 : 00000000 :
0000898c : 00000000 :
00008990 : 00000000 :
00008994 : 00000000 :
00008998 : 00000000 :
0000899c : 00000000 :
000089a0 : 00000000 :
000089a4 : 00000000 :
000089a8 : 00000000 :
000089ac : 00000000 :
000089b0 : 00000000 :
000089b4 : 00000000 :
000089b8 : 00000000 :
000089bc : 00000000 :
000089c0 : 00000000 :
000089c4 : 00000000 :
000089c8 : 00000000 :
000089cc : 00000000 :
000089d0 : 00000000 :
000089d4 : 00000000 :
000089d8 : 00000000 :
000089dc : 00000000 :
000089e0 : 00000000 :
000089e4 : 00000000 :
000089e8 : 00000000 :
000089ec : 00000000 :
000089f0 : 00000000 :
000089f4 : 00000000 :
000089f8 : 00000000 :
000089fc : 00000000 :
00008a00 : 00000000 :
00008a04 : 00000000 :
00008a08 : 00000000 :
00008a0c : 00000000 :
00008a10 : 00000000 :
00008a14 : 00000000 :
00008a18 : 00000000 :
00008a1c : 00000000 :
00008a20 : 00000000 :
00008a24 : 00000000 :
00008a28 : 00000000 :
00008a2c : 00000000 :
00008a30 : 00000000 :
00008a34 : 00000000 :
00008a38 : 00000000 :
00008a3c : 00000000 :
00008a40 : 00000000 :
00008a44 : 00000000 :
00008a48 : 00000000 :
00008a4c : 00000000 :
00008a50 : 00000000 :
00008a54 : 00000000 :
00008a58 : 00000000 :
00008a5c : 00000000 :
00008a60 : 00000000 :
00008a64 : 00000000 :
00008a68 : 00000000 :
00008a6c : 00000000 :
00008a70 : 00000000 :
00008a74 : 00000000 :
00008a78 : 00000000 :
00008a7c : 00000000 :
00008a80 : 00000000 :
00008a84 : 00000000 :
00008a88 : 00000000 :
00008a8c : 00000000 :
00008a90 : 00000000 :
00008a94 : 00000000 :
00008a98 : 00000000 :
00008a9c : 00000000 :
00008aa0 : 00000000 :
00008aa4 : 00000000 :
00008aa8 : 00000000 :
00008aac : 00000000 :
00008ab0 : 00000000 :
00008ab4 : 00000000 :
00008ab8 : 00000000 :
00008abc : 00000000 :
00008ac0 : 00000000 :
00008ac4 : 00000000 :
00008ac8 : 00000000 :

End of dump

Thanks for the report, what did you mean by “open an Obey file to open a task window”? Did you double-click on a TaskObey, or are there commands in the Obey file that open a task window, if so could you paste the file?

In either case, does the crash still happen if you’ve already opened at least one task window in Zap before doing it?

Did you double-click on a TaskObey, or are there commands in the Obey file that open a task window, if so could you paste the file?

Your welcome and thank you for following up. There are commands in the Obey file that open a Task window which I double-click on. See below.

dir <Obey$Dir>
|Set Alias$amu make %*0
filer_run SCSI::HardDisc0.$.Apps.Development.GCC.!GCC
filer_run SCSI::HardDisc0.$.Utilities.!Zap.Resources.UK.Docs.KeyStrip
filer_run SCSI::HardDisc0.$.Apps.Development.!Diderot
filer_run SCSI::HardDisc0.$.Utilities.!StrongHlp
| The following two lines set the libraries for GCC
filer_run SCSI::HardDisc0.$.Apps.Development.GCC.!OSLib.SetVarsELFSCLAPP
filer_run SCSI::HardDisc0.$.Apps.Development.GCC.!OSLibSupp.SetVarsELFSCLAPP
|filer_run SCSI::HardDisc0.$.Apps.Development.GCC.!OSLib.SetVarsELFUnixLib
|filer_run SCSI::HardDisc0.$.Apps.Development.GCC.!OSLibSupp.SetVarsELFUnixLib
| Open a task window with the required memory for GCC to run
TaskWindow  "echo !GCC Running..." -display -wimpslot 16M -name "GCC Terminal"

In either case, does the crash still happen if you’ve already opened at least one task window in Zap before doing it?

The crash occurs at the point where I open the last file. The issue is not only the crash, but it opens another Task window rather than showing the contents of the file.

The error sequence is, I double-click on an Obey file, Task window opens. Then I open a directory with a file in it. I double-click on that file and it crashes and opens another TaskWindow rather than the file that I double-clicked. The files are all in a directory and sub-directory (parent-child). The Obey file is in the parent directory and the other file is in a sub-directory ©.

If I double-click another file for Zap at the same level as the Obey file, it opens the file, then if double-click the Obey file all works as expected.

Another scenario, if I open the file that is in the sub-directory and double-click it, contents displayed, then the Obey file it opens the Task window. No issues.

*Edited to reflect directory structure and file locations

Silly question, but have you tried using StrongED to do the provision of the TaskWindow.

If it crashes in that setup then the problem isn’t in Zap, if it doesn’t crash then the problem is likely in Zap.

Since my initial report, I’ve since discovered that the crash can also be reproduced by opening a generic TaskWindow, and visiting a C file at this depth SCSI::HardDisc0.$.foo.bar.arm.c.main <- c file.

Luckily I suddenly find that I can reproduce this under RPCEmu (but not RPi3). The strange thing is, when I copy the directory tree to a RAM disc the crash doesn’t happen, but it does from HostFS.

I fired up reporter, and intriguingly I find the following line

%TaskWindow -Display -ctrl

which we know causes a problem.

What’s surprising, is that under Zap the task window usually starts successfully using this command, and it’s only in these circumstances that you found that it crashes.

Luckily I suddenly find that I can reproduce this …when I copy the directory tree to a RAM disc the crash doesn’t happen, but it does from HostFS.

Intriguing.

Also “ZapDWExt is not 32 bit compatible”. I discovered this by typing Ctrl-Esc, then Make (Carriage Return). I thought it might be quicker to try that, rather than opening a TaskWindow. :(

Unfortunately we don’t have the source to DWExt to make it 32-bit, so that command will not be available for the time being.

Also “ZapDWExt is not 32 bit compatible”.

Oh, oops. That one slipped through. I though I’d exorcised all of the non-32 bit modules. At least the system refused to load it. ;-)

Hmm – what does ZapDWExt do?

It provides you with a variety of handy commands for programming (C mainly), like switch between source file and header or close all throwback windows. Some of the commands are already available from other modules. There’s a full list in ZapDWExt.!Help.

Unfortunately we don’t have the source to DWExt to make it 32-bit, so that command will not be available for the time being.

I have a BASIC assembly source file for DWExt from !Zap 1.42.

If anyone wants it, just email me at the address at the bottom of http://duncan-moore.netau.net/riscos/index.html , and I’ll send a copy.

Andrew, if you use the 5.29 nightly ROM build then it now (after a long delay on my part) contains a fixed TaskWindow module for testing.

Hi Julie, I’ve updated it to 5.29 (1-Aug-21). I have ZapTaskWindow 1.03, and the build shows TaskWindow 0.83 (31 Jul 2021).

Debug output:

Error block: 80000002 Internal error: abort on data transfer at &203D3AD8
R0 = 0002b2c0
R1 = 6572206f
R2 = 00000000
R3 = 00033ba0
R4 = 02051008
R5 = 00037170
R6 = 00033a60
R7 = 00037170
R8 = 0002bfa4
R9 = 0002c2e0
R10 = 00037a1c
R11 = 00000000
R12 = 203aaff4
R13 = 000086cc
R14 = 203d3adc
R15 = 203d3ae0
CPSR = 40000110
R13_usr = 000086cc
R14_usr = 203d3adc
R13_svc = fa208000
R14_svc = 20372f10
SPSR_svc = 80000110
R13_irq = fa102000
R14_irq = 80000113
SPSR_irq = 80000113
R13_abt = fa301fa8
R14_abt = 203d3ae0
SPSR_abt = 40000110
R13_und = fa402000
R14_und = fc161434
SPSR_und = 60000113
OSMem16: 2 = fa100000, 00002000, 00002000
OSMem16: 3 = fa200000, 00008000, 00008000
OSMem16: 4 = fa300000, 00002000, 00002000
OSMem16: 5 = fa400000, 00002000, 00002000
Memory: fa100000 - fa102000
Memory: fa200000 - fa208000
Memory: fa300000 - fa302000
Memory: fa400000 - fa402000
Memory: ffff0108 - ffff010c
OSRSI6: 69 = ffff0108

R15 = 203d3ae0 = ZapMJE +2bcc
R14_usr = 203d3adc = ZapMJE +2bc8

USR stack:
000086cc : 00000000 :
000086d0 : 00033a60 :
000086d4 : 20373d90 : - Return to 20373d90?
         :          : | = Zap +19bc
         :          : | = redraw_cache_line +80
000086d8 : 00000148 : - R2
000086dc : 00000001 : | R3
000086e0 : 00000001 : | R4
000086e4 : ffffffff : | R5
000086e8 : 00033a58 : | R6
000086ec : 00000000 : | R10
000086f0 : 20373b04 : | R14: 20373b04 (ASM call to 20373d10)
         :          : | 20373b04 = Zap +1730
         :          : | = red_cache_lines +84
         :          : | 20373d10 = Zap +193c
         :          : | = redraw_cache_line +0
000086f4 : 00000000 :
000086f8 : 00000000 :
000086fc : 00000000 : - R2
00008700 : 00000001 : | R3
00008704 : 00000000 : | R4
00008708 : 00000000 : | R5
0000870c : 2037399c : | R14: 2037399c (ASM call to 20373a80)
         :          : | 2037399c = Zap +15c8
         :          : | = update_cache +13c
         :          : | 20373a80 = Zap +16ac
         :          : | = red_cache_lines +0
00008710 : 203ab04c :                                            - R1
00008714 : 00000000 :                                            | R2
00008718 : 00000001 :                                            | R3
0000871c : 00000000 :                                            | R4
00008720 : 0000069e :                                            | R5
00008724 : 20054828 :                                            | R6
00008728 : 00000000 :                                            | R7
0000872c : 0002bfa4 :                                            | R8
00008730 : 0002c2e0 :                                            | R9
00008734 : 00009498 :                                            | R10
00008738 : 203d57e0 : - Return to 203d57e0?                      | R11
         :          : | = ZapMJE +48cc                           | 
0000873c : 20372cd0 :                                            | R14: 20372cd0 (ASM call to 20373860)
         :          :                                            | 20372cd0 = Zap +8fc
         :          :                                            | = redraw_window +c
         :          :                                            | 20373860 = Zap +148c
         :          :                                            | = update_cache +0
00008740 : 00009108 : - R1
00008744 : 00000010 : | R2
00008748 : ffffffde : | R3
0000874c : 00000000 : | R4
00008750 : 2037438c : | R14: 2037438c (ASM call to 20372cc4)
         :          : | 2037438c = Zap +1fb8
         :          : | = update_window +14
         :          : | 20372cc4 = Zap +8f0
         :          : | = redraw_window +0
00008754 : 00009108 : - R1
00008758 : 2037435c : | R14: 2037435c (ASM call to 20374378)
         :          : | 2037435c = Zap +1f88
         :          : | = update_area +4c
         :          : | 20374378 = Zap +1fa4
         :          : | = update_window +0
0000875c : 00009108 : - R1
00008760 : 00000000 : | R2
00008764 : 20059c38 : | R3
00008768 : 00000ee0 : | R4
0000876c : 203797e4 : | R14: 203797e4 (ASM call to 20374310)
         :          : | 203797e4 = Zap +7410
         :          : | = clear_caret +64
         :          : | 20374310 = Zap +1f3c
         :          : | = update_area +0
00008770 : 00000000 :
00008774 : 0002bfa4 :
00008778 : 0002c2e0 :
0000877c : 20379b5c : - 20379780 return to 20379b5c?
         :          : | 20379780 = Zap +73ac
         :          : | = clear_caret +0
         :          : | 20379b5c = Zap +7788
         :          : | = null_caret +1c
00008780 : 20379a68 : - R14: 20379a68 (ASM call to 20379b40)
         :          : | 20379a68 = Zap +7694
         :          : | = set_caret_mode_from1 +34
         :          : | 20379b40 = Zap +776c
         :          : | = null_caret +0
00008784 : 00000000 :                                            - R1
00008788 : 00000000 :                                            | R2
0000878c : 20059c38 :                                            | R3
00008790 : 00000ee0 :                                            | R4
00008794 : 0000069e :                                            | R5
00008798 : 20054828 :                                            | R6
0000879c : 00000000 :                                            | R7
000087a0 : 0002bfa4 :                                            | R8
000087a4 : 0002c2e0 :                                            | R9
000087a8 : 00009498 :                                            | R10
000087ac : 203d57e0 : - Return to 203d57e0?                      | R11
         :          : | = ZapMJE +48cc                           | 
000087b0 : 20379944 :                                            | R14: 20379944 (ASM call to 20379a34)
         :          :                                            | 20379944 = Zap +7570
         :          :                                            | = set_caret_mode +34
         :          :                                            | 20379a34 = Zap +7660
         :          :                                            | = set_caret_mode_from1 +0
000087b4 : 00000004 : - R1
000087b8 : 20379d5c : | R14: 20379d5c (ASM call to 20379910)
         :          : | 20379d5c = Zap +7988
         :          : | = delete_carets +38
         :          : | 20379910 = Zap +753c
         :          : | = set_caret_mode +0
000087bc : 20399208 : - R10
000087c0 : 2037c9d4 : | R14: 2037c9d4 (ASM call to 20379d24)
         :          : | 2037c9d4 = Zap +a600
         :          : | = discard_window +84
         :          : | 20379d24 = Zap +7950
         :          : | = delete_carets +0
000087c4 : 00000003 :
000087c8 : 2037db24 : - Return to 2037db24?
         :          : | = Zap +b750
         :          : | = do_eachwindow +50
000087cc : 00001ae0 : - R8
000087d0 : 00000000 : | R11
000087d4 : 203991ec : | R14: 203991ec (ASM call to 2037dad4)
         :          : | 203991ec = Zap +26e18
         :          : | = discard_file +84
         :          : | 2037dad4 = Zap +b700
         :          : | = do_eachwindow +0
000087d8 : 00000000 :
000087dc : 2039916c :
000087e0 : 00000000 :
000087e4 : 20396720 : - Return to 20396720?
         :          : | = Zap +2434c
         :          : | = do_allfiles +34
000087e8 : 00000b40 : - R9
000087ec : 20054798 : | R11
000087f0 : 2039a31c : | R14: 2039a31c (ASM call to 203966ec)
         :          : | 2039a31c = Zap +27f48
         :          : | = dump_file +170
         :          : | 203966ec = Zap +24318
         :          : | = do_allfiles +0
000087f4 : 2017f6f8 : - R10
000087f8 : 203a0ea8 : | R14: 203a0ea8 (ASM call to 2039a30c)
         :          : | 203a0ea8 = Zap +2ead4
         :          : | = clean_up +1c
         :          : | 2039a30c = Zap +27f38
         :          : | = dump_file +160
000087fc : 203aa9c0 : - R14: 203aa9c0 (ASM call to 203a0e8c)
         :          : | 203aa9c0 = Zap +385ec
         :          : | = ExitHandler +14
         :          : | 203a0e8c = Zap +2eab8
         :          : | = clean_up +0
00008800 : 0070615a :
00008804 : e3a02001 :
00008808 : 20367c99 :
0000880c : 00000a9a :
00008810 : 0000044e :
00008814 : 00000f72 :
00008818 : 000009f0 :
0000881c : fffffffc :
00008820 : 00000000 :
00008824 : 00000bfc :
00008828 : 000004c4 :
0000882c : 00000ee0 :
00008830 : 0000069e :
00008834 : 49534353 :
00008838 : 61483a3a :
0000883c : 69446472 :
00008840 : 2e306373 :
00008844 : 6f432e24 :
00008848 : 502e6564 :
0000884c : 74636172 :
00008850 : 2e656369 :
00008854 : 6c6f6f54 :
00008858 : 2e786f42 :
0000885c : 616d2e63 :
00008860 : 4d006e69 :
00008864 : 00000000 :
00008868 : 00000000 :
0000886c : 00000000 :
00008870 : 00000000 :
00008874 : 00000000 :
00008878 : 00000000 :
0000887c : 00000000 :
00008880 : 00000000 :
00008884 : 00000000 :
00008888 : 00000000 :
0000888c : 00000000 :
00008890 : 00000000 :
00008894 : 00000000 :
00008898 : 00000000 :
0000889c : 00000000 :
000088a0 : 00000000 :
000088a4 : 00000000 :
000088a8 : 00000000 :
000088ac : 00000000 :
000088b0 : 00000000 :
000088b4 : 00000000 :
000088b8 : 00000000 :
000088bc : 00000000 :
000088c0 : 00000000 :
000088c4 : 00000000 :
000088c8 : 00000000 :
000088cc : 00000000 :
000088d0 : 00000000 :
000088d4 : 00000000 :
000088d8 : 00000000 :
000088dc : 00000000 :
000088e0 : 00000000 :
000088e4 : 00000000 :
000088e8 : 00000000 :
000088ec : 00000000 :
000088f0 : 00000000 :
000088f4 : 00000000 :
000088f8 : 00000000 :
000088fc : 00000000 :
00008900 : 00000000 :
00008904 : 00000000 :
00008908 : 20367c99 :
0000890c : 0000045d :
00008910 : 00000302 :
00008914 : 000015d6 :
00008918 : 000008a2 :
0000891c : fffffffc :
00008920 : 00000000 :
00008924 : ffffffff :
00008928 : ff000102 :
0000892c : ff070207 :
00008930 : 000c0103 :
00008934 : fffffffc :
00008938 : fffff4c0 :
0000893c : 000004d4 :
00008940 : 00000000 :
00008944 : 0000013d :
00008948 : 20367c99 :
0000894c : 0000045c :
00008950 : 00000302 :
00008954 : 00000934 :
00008958 : 000008a2 :
0000895c : fffffffc :
00008960 : 00000000 :
00008964 : ffffffff :
00008968 : ff130102 :
0000896c : 00000000 :
<-Snipped->
00008ac8 : 00000000 :

End of dump 

Oh well the search continues then. Experimenting on RPCemu, I get it to reproduce as

1) Create a text file HostFS::HostFS.$.01234567890123456789012.c.a containing nine linefeed (CHR$10) characters.
2) Run Zap
3) Iconbar > Create > Task window
4) Double-click on text file a.

If a doesn’t have enough line feeds, you can get it to crash by pressing enter. N.B. It’s sensitive to the length of path, so on RamFS would need to make directory or filename longer.

:) Thanks Julie, after repeating the steps to cause a crash, I discovered a way to run a task window under another editor (StrongEd and Edit)

*where
Address &20412CD4 is at offset &00000CC0 in module 'LineEditor'

My only concern is that loading a new editor changes what might be expected when *where is run.

Edit: The only constants I see here are the traversal depth, opening a task window, and then the file. I chose a different directory at the same level. Sadly the observation isn’t the same, but it causes a freeze on Shutdown; Ctrl-Break is the only way out.