https://pushbx.org/ecm/dokuwiki/ 2026-04-11T07:03:38+00:00 https://pushbx.org/ecm/dokuwiki/ https://pushbx.org/ecm/dokuwiki/lib/tpl/dokuwiki/images/favicon.ico text/html 2022-04-19T14:31:31+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0419_hello_world?rev=1650371491&do=diff Hello world! Some 13 years after the first "push bx" blog here is a new iteration on the same theme. This blog is for random tech related topics. Like my work so far this will probably mostly be about 8086 assembly and 86 DOS programming. hello pushbx blogging text/html 2022-04-24T14:12:06+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0424_ldebug_expression_evaluator_learns_to_use_types_poorly?rev=1650802326&do=diff lDebug expression evaluator learns to use types (poorly) One week ago I finally had to confront a long-standing defect in lDebug's expression evaluator: It didn't support types. I found out because all numbers that were "negative" in two's complement (ie values that are >= text/html 2022-04-24T14:35:32+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0424_ldebugx_compatibility_tweaks_dosemu2_native_dpmi_bugfix?rev=1650803732&do=diff lDebugX compatibility tweaks, dosemu2 native DPMI bugfix After some discussion on lDebugX running a DPMI client in dosemu2 on a hosteurope virtual server, several changes were made to both lDebugX and dosemu2. dosemu2 got a genuine bugfix out of this. Or two. Or three. lDebugX changes include: text/html 2022-04-27T17:02:54+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0427_hg_rebase_--config_rebase.norebasesource_1?rev=1651071774&do=diff hg rebase --config rebase.norebasesource=1 Today a patch I sent to mercurial-devel was allowlisted. It is reproduced here for reference. rebase: add boolean config item rebase.norebasesource This allows to use rebase without recording a rebase_source extra field. This is useful for example to build a mirror converted from another SCM (such as svn) by converting only new revisions, and then incrementally add them to the destination by pulling from the newly converted (unrelated) repo and rebas… text/html 2022-05-06T16:45:26+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0506_embarrassing_ldebug_bug_in_ensuredebuggeeloaded?rev=1651848326&do=diff Embarrassing lDebug bug in ensuredebuggeeloaded While modifying lDebug's ensuredebuggeeloaded, which is responsible for creating an empty process as a debuggee, I erred severely early in the morning of last Wednesday. The bug was that I moved around a call to .zeroregs (later made into a non-local function) to after the attempt to allocate memory for the new process-to-be. However, text/html 2023-11-20T09:37:09+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0509_mov_fast_and_mak_things?rev=1700469429&do=diff mov fast and mak things Why 'Move Fast and Break Things' Doesn’t Workin the Internet Archive mov is of course an 8086 instruction, and mak is a script name for build scripts that I tend to use, most intricately to build lDebug. hello blogging mov mak idioms text/html 2022-07-07T19:15:16+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0706_ldebug_symbolic_and_segment_splits?rev=1657214116&do=diff lDebug, symbolic, and segment splits The Return of the Symbolic Branch! Recent comments by Bret Johnson caused me to revisit the symbolic branch of lDebug. These were one and two, referencing my earlier reply to this thread on DOS assembly language resources. In particular, the second message ends in: text/html 2022-08-04T22:00:36+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0804_conditionally_debuggable_ldebug?rev=1659643236&do=diff Conditionally Debuggable lDebug The "go everywhere, do everything" theme of lDebug has gained a new feature: Conditionally Debuggable builds allow to switch between the non-debuggable mode (handlers are hooked when the debugger starts up and unhooked only when it terminates), and the debuggable mode. text/html 2022-08-07T00:50:36+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0807_ldebug_caught_up_with_freedos_debug_and_ancient_change_log?rev=1659826236&do=diff lDebug caught up with FreeDOS Debug, and ancient change log As mentioned in the prior blog post lDebug very much has a "go everywhere, do everything" theme. Today we're caught up with FreeDOS Debug again for the most part. (Still missing is the patch to use the test_high_limit text/html 2022-08-26T21:37:33+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0826_dual_code_segments_mechanisms?rev=1661542653&do=diff Dual code segments mechanisms The macros for dual code segment support contain two different macros for differently handling inter-segment calls. The easier to use is the nearcall macro. If calling within the same segment it simply expands to a near immediate call (opcode 0E8h). Otherwise it calls a helper function, with a target offset to call stored in the code behind the helper function call opcode. This helper thunk will rearrange the stack so that it branches far to the desired target, … text/html 2022-08-26T01:06:20+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0826_recent_segmentation_in_ldebug_and_not_yet_merged_nasm_patches?rev=1661468780&do=diff Recent segmentation in lDebug and not yet merged NASM patches The lDebug debugger is a demanding application. It's driven NASM bug reports for a while now. There are 63 tickets filed by me in the NASM bugzilla, most of which cropped up during lDebug development. As described in 2022 July, the debugger's footprint has grown beyond 64 KiB segment limits twice now. text/html 2022-09-20T23:03:23+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0919_hello_from_the_hp_95lx?rev=1663707803&do=diff Hello from the HP 95LX! 2022-09-18 This post is the first work I have created using the Memo application on the first HP 95LX that I recently acquired. I did use Memo previously to create a few script files, mainly to start and configure lDebug. text/html 2022-09-24T19:33:32+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0924_more_hp_95lx_adventures?rev=1664040812&do=diff More HP 95LX adventures 2022-09-20 Yesterday I loaded a bunch of files onto the HP 95LX, intending to read on the device. I used some nondescript "PDF to text" website to gain plain text from two PDFs. Next, I attempted to convert the resulting Big Text File from the UTF-8 encoding to Code Page 850 using iconv. This repeatedly complained about invalid codepoints. I manually search-and-replaced all the smartquotes and friends (using Pluma, the text editor of the MATE Desktop Environment). After… text/html 2022-09-27T20:00:24+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0927_script_for_ldebug_sld_file_for_the_hp_95lx_and_more_ldebug_development?rev=1664301624&do=diff Script for lDebug (SLD) file for the HP 95LX, and more lDebug development 2022-09-25 Having adjusted the R, U, D, and E commands to be more 40-column friendly I am currently using the following script for lDebug (sld) file to set up the debugger: r dco or= 800 r dco6 or= 1200 r dco2 or= 111 r ior = #16 r ioc = #40 r dao or= 80 text/html 2022-10-02T05:54:29+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0929_95lx_file_transfer_woes_and_backup_battery_tray?rev=1664682869&do=diff 95LX file transfer woes and backup battery tray 2022-09-28 Yesterday while setting up the file transfer between the HP 95LX and the Linux box I noticed that I'd bent one of the pins on the 95LX's serial connector. Luckily it was one of the outer pins, not the inner two which actually carry data. I returned it into the correct position with some difficulty, using tweezers. text/html 2022-09-29T19:47:03+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/0929_request_for_comments_-_please_reply_to_this_post?rev=1664473623&do=diff Request For Comments - please reply to this post! 2022-09-29 RFC! I am requesting all readers of this post to comment on here to let me gauge interest in this blog. Whether you're reading this today or at any point in the future: Make a noise! If this blog no longer exists or you wish to do so, I'd also like to encourage you to write about the pushbx blog elsewhere. If you have any particular favourite topics or posts I'd also be interested in learning about those. text/html 2022-10-16T15:13:55+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1016_95lx_hang_pdzm_zip_ldebug_line_history_comments?rev=1665926035&do=diff 95LX hang, PDZM, Zip, lDebug line history comments 2022-10-11 The other day I managed to hang the 95LX again, to the point that Ctrl-Alt-Del did not work. This time I used Shift-Ctrl-On to reset the system. This reboots and queries whether to re-initialise the RAM disk. I chose "No". I found that while the disk contents and settings where preserved, the current date and time were not. (Supposedly this way of resetting may damage the RAM disk contents even if you reply not to reset the disk mem… text/html 2022-10-23T17:49:07+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1023_95lx_sending_at_57600_baud_line_history_optimisations_third_95lx?rev=1666540147&do=diff 95LX sending at 57600 baud, line history optimisations, third 95LX 2022-10-16 Today during the file transfer between the HP 95LX (running PD ZModem version 1.26) and the Linux box (running Debian's sz/rz) I tried out sending from the 95LX at 57600 baud. I used the command line text/html 2022-10-31T09:58:15+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1031_rest_in_pieces_95lx?rev=1667206695&do=diff Rest In Pieces, 95LX 2022-10-23 Today I found that the first 95LX's screen had an error, in which the last line of the screen did not display correctly. I decided to try to open the device and reseat the screen connector. Unfortunately I broke it in new and exciting ways, now the keyboard is somewhat broken, and to add insult to injury I didn't even fix the original problem. So I will use the third 95LX starting today. I have gained the renewed insight that I am no good at handling hardware… text/html 2022-10-31T10:11:15+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1031_the_usb_device_for_the_95lx?rev=1667207475&do=diff The USB device for the 95LX 2022-10-31 Yesterday in the evening I was actually reminded that I am, in loose terms, using a USB device with the 95LX. Now of course the 95LX doesn't have any USB ports or controllers. But it's a lamp that draws power from a USB connector, which is plugged into a USB power adapter, on my nightstand. As the screen of the 95LX isn't lit a lamp is necessary at night time. text/html 2022-10-31T16:40:11+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1031_unmak_explanations_and_plans?rev=1667230811&do=diff unmak explanations and plans 2022-10-30 I didn't get to use the (third) 95LX that much this week, though I did read a few more chapters of a story. Right now my modern mobile device shut down due to a discharged battery (without warning) so I might as well spend some time writing on the 95LX again. text/html 2022-11-07T22:54:44+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1107_bootable_ldebug_vs_freedos_debugb?rev=1667858084&do=diff Bootable lDebug vs FreeDOS DebugB FreeDOS Debug got a new build variant earlier: DebugB. It is implemented by these two git revisions so far: 88a97d7 and the subsequent 4ae8e41. Let's compare and contrast it with lDebug's boot mode support! FreeDOS DebugB documentation text/html 2022-11-13T15:21:17+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1107_ldos_boot_loader_review?rev=1668349277&do=diff lDOS boot loader review 2022-11-06 This week I went and reviewed the ldosboot boot sector loaders for a while, particularly the interaction between the FAT32 first stage and its associated second stage. This second stage is called FSIBOOT. FSIBOOT and ranboot text/html 2023-10-09T09:45:22+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1110_debugging_and_programming_adage?rev=1696837522&do=diff Debugging and programming adage thedailywtf.com commentuser Nutster idioms text/html 2022-11-11T20:44:15+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1111_lcdebug_image_for_use_with_pcjs.org?rev=1668195855&do=diff lCDebug image for use with pcjs.org It isn't the latest and greatest, but in August I uploaded an lCDebug diskette image to our server with the prerequisite .htaccess file to allow pcjs.org to access it. The file is at <https://pushbx.org/ecm/test/20220819/bcdebug.img> To allow pcjs.org to load from our server, a cross-site load needs to be enabled. This is the required text/html 2022-11-11T21:11:12+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1111_ldebug_bootunitflx_flag_2_to_force_using_bpb_geometry?rev=1668197472&do=diff lDebug: BOOTUNITFLx flag 2 to force using BPB geometry After having found that some pcjs.org machines report wrong CHS geometries on function 13.08, I prepared a flag that can be set in lDebug's BOOTUNITFLx variables to force falling back to the geometry noted in a unit's BPB. (For now this blindly assumes that the unit starts with a boot sector with BPB, even if the unit is actually >= 80h and partitioned with an MBR.) text/html 2022-11-11T19:58:55+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1111_link_spam?rev=1668193135&do=diff Link spam Here's some links I happened to have lying around. This may become a regular type of contribution to this blog. b16cat and echoify <https://hg.pushbx.org/ecm/b16cat> dosemu -K "$PWD" -E "ldebug /c='y b16cat.sld'" -dumb gcc -O2 echoify.c -o echoify ./echoify b16cat.com text/html 2022-11-15T18:31:50+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1115_ldos_boot_work_continues?rev=1668533510&do=diff lDOS boot work continues 2022-11-13 The optimisations of ldosboot continue, although I previously considered it impossible to optimise further. Optimisations First, iniload saved a few bytes by falling through in .int13_retry to re-use the .int13_preserve_lpcount code instead of calling it then doing text/html 2022-11-21T18:35:31+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1121_ldebug_e_inicomp_review_and_a_change?rev=1669052131&do=diff lDebug /E, inicomp review and a change 2022-11-19 This week I added another switch to lDebug to support using it for offline patching of iniload files (such as the debugger's own executable), even if the file exceeds 64 KiB. Without the /E switch or its associated DCO6 option text/html 2022-11-26T22:11:38+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1126_ldebug_debug_x_2.00_nasm_lz4_depacker_for_vgapride?rev=1669497098&do=diff lDebug, Debug/X 2.00, NASM, LZ4 depacker for VGAPride 2022-11-25 Recently I fixed a few bugs in lDebug and added two new address keywords. Other than that, the original Debug/X just jumped to version 2.00. The bugs The first bug was that leading blanks in commands read from the /C= switch or from the kernel command line were included verbatim instead of trimmed. This had the effect of indenting these commands oddly. (At first I believed this was due to lCDebug's conditional tilde in the prom… text/html 2022-12-06T19:17:12+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1206_acquired_an_1_mib_model_of_the_hp_95lx?rev=1670350632&do=diff Acquired an 1 MiB model of the HP 95LX 2022-12-01 This week rr made me aware of another offer of an HP 95LX. This one happened to be the variant extended to have 1 MiB of internal memory. This is the rarer model. After the price dropped a bit, I decided to buy it on Tuesday after 20:00. The seller was very quick to respond and agreed to ship it the next day. However, yesterday the seller contacted me again and suggested they could deliver it personally, today, as they would travel to Düssel… text/html 2022-12-06T19:21:00+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1206_ldebugx_fixes_bootable_ldebug_fix_and_extension_hp_95lx_powered_transfer?rev=1670350860&do=diff lDebugX fixes, bootable lDebug fix and extension, HP 95LX powered transfer 2022-11-27 In the past days, lDebugX received some attention which was initiated by a bugfix in FreeDOS Debug/X. That bug was the fact that parsecm (the function to parse C and M commands) used text/html 2022-12-14T13:30:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1214_more_ldebug_work_early_december?rev=1671021056&do=diff More lDebug work, early December 2022-12-11 Some more work on lDebug happened recently. M command dispatching changes Another change inspired by (FreeDOS) Debug/X, the M commands were changed so as to detect the single-expression machine-type related M commands differently. This allows to use the dollar sign prefix for the first address of a memory move M command. (This prefix forces use of a segmented address with a 86 Mode segment instead of a selector in Protected Mode. It is accepted as … text/html 2022-12-17T13:20:01+00:00 Anonymous (anonymous@undisclosed.example.com) https://pushbx.org/ecm/dokuwiki/blog/pushbx/2022/1217_new_95lx_setup_script_for_ldebug?rev=1671279601&do=diff New 95LX setup Script for lDebug Today I updated the lCDebug executable on the HP 95LX. I also changed the 95lx.sld file. Some flags moved around for the disassembler, and the default length of the D and U commands can now be modified. I chose to set a default length of 12 "lines". (The "lines" count does not always correspond exactly to lines displayed.)