The road from the first public pre-release to version 1.0, in chronological order. All releases are available at https://github.com/Projanglez/ftp4dos/releases; every release ships the DOS executable plus the exact mTCP sources it links against (GPLv3 §6).
Norton Commander-style dual-pane FTP client for MS-DOS on real x86 hardware, built with Open Watcom and mTCP.
- Two panes: local (DOS) and remote (FTP, passive mode)
- Copy in both directions (F5), including recursive directory trees
- Multiple selection with the Ins key (Norton style) for copy/delete
- Create (F7), rename (F6), recursive delete with pre-count confirmation (F8)
- File viewer (F3, up to 32 KB; remote files download to a temp file first) and a minimal local text editor (F4)
- Connection keepalive (NOOP every 60 s)
- Bilingual German/English UI, auto-detected from the DOS country setting
- Tested on real 386 hardware with a genuine LAN card
- Migrated from the retrohun mTCP fork to the official mTCP 2025-01-10 release (brutman.com, GPLv3)
- All source code comments translated to English
- Renamed NCFTP386 → FTP4DOS (thanks to Yoghoo on VOGONS for the suggestion)
- Swap panes with Ctrl+U (remembered across launches)
- Move with F6 (copy + delete source, recursive); rename moved to Alt+F6
- FTP pane preserves the server's original (case-sensitive) file names
- Monochrome (MDA/Hercules) support;
/MONOand/COLORoverrides - ALT command bar (Norton-style): Alt+F1 Drive, Alt+F6 Rename
- Confirmation dialogs default to Yes
- Live transfer telemetry: current/average speed, per-file and batch ETA
- Pause (P) and cancel (ESC) during transfers
- Copy/Move/Delete confirmations show recursive counts and total size
- Alt+F9: file checksums (CRC32 + MD5), local and remote
- Alt+F3: configurable per-pane sorting
- Compact M/G size display; locale-aware number/date/time formatting
- Comfortable input fields everywhere (cursor movement, Home/End, Del, mid-line insert)
- Alt+F2 "Detail": full (untruncated) name and exact size of an entry
- Alt+F5 / F9: refresh the active pane
- No more
..entry at the FTP root - Consistent 1024-based KB/MB/GB sizes throughout
- Site manager: multiple named connection profiles in
FTP4DOS.SIT, reached via [Manage...] in the connect dialog /EXMEM: store large remote listings (thousands of entries) in extended (XMS) or expanded (EMS) memory instead of the 512-entry default- Search / jump-to-name (Alt+F7 / Ctrl+F)
- Long remote file names kept in full and used for transfers
- Full-screen pane toggle (Alt+F8)
- FTP start directory (connect dialog and
/D:DIR); remembered sort order - Fix: entering remote directories with names longer than 39 characters
- Fix: downloading files with multi-dot / long names (e.g.
apack-1.00.zip) maps to a valid DOS 8.3 target instead of failing - Ctrl+C as shortcut for "compare panes" (BIOS keyboard read, no more
stray
^C) - Date and Time sorting merged into one Date/Time criterion
Driven by feedback in the VOGONS thread — thanks to mbbrutman, ntalaec, Falcosoft, Grzyb and fly_indiz.
- Faster transfers: downloads write to disk in large buffered blocks
instead of many small per-packet writes; buffer sizes tunable via
FTP4DOS_TCP_BUFFER/FTP4DOS_FILE_BUFFERinMTCP.CFG(the mTCP FTP client'sFTP_TCP_BUFFER/FTP_FILE_BUFFERare read as fallbacks) - UTF-8 file names (RFC 2640): converted to the active DOS codepage
(CP437, CP850/858, CP866;
FTP4DOS_CODEPAGEoverride) for display and local names; uploads to UTF-8 servers are encoded back (OPTS UTF8 ON) - Long file names (LFN) in the local pane on Windows 9x DOS, MS-DOS 7.x, or DOSLFN; includes a fix for a false-positive LFN detection on MS-DOS 6.22
- mTCP is now referenced as a git submodule of the official repository https://github.com/mbbrutman/mTCP, pinned to the 2025-01-10 release tag
The first stable release, verified on real 386 hardware. Driven by the v0.9.6 feedback round on VOGONS — thanks to fly_indiz and ntalaec.
- Steadier download speeds: disk writes no longer starve the network stack — the file buffer is flushed in slices with packet processing in between, avoiding the burst/stall sawtooth seen on real hardware
- Cancelling a transfer is instant instead of freezing the progress dialog for up to 10 seconds (ABOR is now sent while the data connection is still open, mirroring the upload path)
- Control-connection resync: stale replies left over from aborted or timed-out transfers no longer desync later commands (the reported "PASV refused (257)"); a server-side idle timeout (421) now cleanly reports "connection lost" instead of failing later
- Long filenames actually work now (the v0.9.6 LFN support was only ever exercised on plain DOS): detection uses the documented Get Volume Information call instead of the undocumented probe that only Windows 9x answers (fixes DOSLFN on MS-DOS 7.x), the 714Eh find-data record layout and attribute mask were wrong (garbage names, missing directories), and all file operations route through the LFN API or the 8.3 alias — enter long-named directories, view/copy/delete/rename long-named files, download to long names, create long-named directories
- UTF-8 remote paths are codepage-converted in the pane header (file lists already were); cursor reselection after leaving a UTF-8-named directory works
/SITESswitch: open the site manager directly on startup- Deterministic 8.3 download names, Move+Skip no longer loses files, overflow guard for >4 GB counters
A bug-fix and minor improvement release for the v1.0.0 feedback round on VOGONS — thanks to Yoghoo, ntalaec, Grzyb and fly_indiz.
- Downloads no longer fail or silently produce 0-byte files on systems with long filename support (DOSBox-X, MS-DOS 7.x + DOSLFN, Windows 9x DOS): a long-named target was created through the DOS extended-open call and the handle handed to the C library, which does not accept a handle it did not open itself. The long name is now created first and all file I/O goes through its 8.3 alias
- Directories with thousands of long file names work in full. The name
buffer was capped at one conventional-memory segment, so past roughly
600-1700 entries names were silently shortened to a 39-character prefix —
and that prefix went out verbatim in
RETR/CWD/DELE, producing a "550 No such file" on entries plainly visible in the pane. Name storage now moves into XMS/EMS along with the entry records; a name that still does not fit is marked>and refused up front - Extended memory is used automatically when available instead of
requiring
/EXMEM— but only when it actually yields more entries than the 512 of the conventional list;/NOEXMEMopts out entirely - Recursive copies are no longer limited to 400 entries per directory (2048 now, stepping down only as far as free conventional memory requires; the message names the limit actually in force)
- Cancelling a transfer completes in well under a second (~0.9 s on a 20 MB download) instead of freezing the progress dialog for up to 20 seconds
- Progress, speed and ETA keep moving during a recursive copy: small
files that arrived in one go never reported their bytes, freezing the
display on the last large file. The estimate now also accounts for
per-file overhead (
PASV/RETR/226round trip, open/close, listing), and directory copies show the total remaining time, not just the per-file one - Real timestamps for remote files via
MLSD(RFC 3659), with fallback toLIST;ls -lomits the time of day for entries older than about six months, which is why archive directories showed00:00on every row. WhereLISTis used, those entries now show the year. Note thatMLSDreports UTC /LASTCON: connect straight to the last used connection on startup with no dialog —FTP4DOS /Q /LASTCONneeds no batch file- Transfer diagnostics:
FTP4DOS_XFERLOGinMTCP.CFGwrites one line per second during a transfer (elapsed, bytes total, bytes in the last second, receive/idle/disk-write counts, buffer fill); off by default - The local pane preserves the case of long file names (the Norton uppercase/lowercase convention now applies to genuine 8.3 names only), and 8.3 names on the FTP side are shown lowercase to match
- Fixes: an empty directory on an LFN system could show no
..entry; the name buffer could fail to allocate at all with little free conventional memory
Automatic updates
- Alt+F10 checks for a new version, downloads it and installs it on exit.
The previous executable is kept as
FTP4DOS.BAK. - Every update is RSA-2048 signed. The manifest carries the SHA-256 of the executable and is signed with a key whose private half never leaves the maintainer's machine; the public keys are compiled into FTP4DOS. A manifest that does not verify is refused outright — there is no override. This matters because the transport cannot be encrypted: mTCP has no TLS, so authenticity comes from the signature rather than from the connection.
- Optional startup check, off by default, at most once a week, and it never
does more than write a line in the status bar. New switches
/UPDATECHECKand/NOUPDATECHECK; the setting lives inFTP4DOS.SAVasupdcheck. - The update channel is a small Cloudflare Worker that reads this repository's latest GitHub release and serves it over plain HTTP, because GitHub requires HTTPS.
- New: SHA-256 (
sha256.cpp) and an RSA-2048 PKCS#1 v1.5 verifier (rsaverify.cpp), both 16-bit real mode, no assembly, still-0/8086. - The socket-to-disk transfer core moved to
netcore.cppso HTTP downloads use the same proven path as FTP — including the Silly Window Syndrome handling that large downloads depend on.
Image viewing
- F3 and Enter show images, in 320x200 with 256 colours on any VGA: BMP (1/4/8/24/32 bpp, uncompressed plus RLE8 and RLE4), PCX, GIF including interlaced, and PNG. The format is detected from the file's content, not its extension, so a mislabelled download still opens.
- Pan and zoom. A picture opens fitted to the screen, or 1:1 if it already
fits;
+/-step through 25/50/100/200/400/800 %, the arrow keys and PgUp/PgDn move around,*jumps to 1:1,freturns to fit, and the current zoom is shown in the top right corner. This matters on a 720x400 screenshot, where fitting to 320x200 throws away three quarters of the pixels and the text in it stops being readable. - Palette images get their exact colours, loaded straight into the VGA DAC. Truecolour is quantised to a 6x6x6 cube with a 40-step grey ramp and 4x4 ordered dithering; PNG alpha is composited rather than discarded.
- No decoder ever holds the whole picture. Rows arrive one at a time, each carrying its own destination index, which is what makes bottom-up BMP, interlaced GIF and RLE deltas work in a fixed amount of memory.
- The decoded picture is kept in XMS/EMS (through the same
extmem.cppthe panel store uses) at one byte per pixel, so panning and zooming re-sample an image already in memory instead of decoding the file again: a 720x400 picture is 288000 bytes and could never live in conventional memory. Without extended memory the fitted view still works, just without pan and zoom. - Decoding happens before the display switches to graphics, so a damaged file produces an ordinary dialog on an intact screen, and Esc aborts a slow decode.
- F1 reports free conventional memory. A picture needs about 100 KB of it, so that figure is what decides whether one can be shown; the out-of-memory dialog repeats it.
- Not decoded, and refused with a clear message rather than a guess: JPEG, TIFF, interlaced PNG, and BMP variants beyond those listed.
Performance fix for /EXMEM (now the default remote-panel backend)
- Cursor movement no longer rescans the whole listing. The status bar's marked-count/size/dir-count were recomputed by scanning every entry on each arrow-key press, even with nothing marked. Under /EXMEM that meant a real-mode XMS/EMS driver call per entry per keypress - the main cause of the slowdown since /EXMEM became the default. The totals are now tracked incrementally instead, so the status bar is O(1) regardless of listing size or backend.
clear_marks()also skips its scan entirely when nothing is marked.
Small machines: memory, throughput, and no more silent failures
- An empty remote pane now says why. A connect that succeeded but whose
first
LISTfailed used to leave a blank blue pane and no message — it took several people and several rounds to work out that the machine had simply run out of conventional memory. Failed listings are now reported, with the amount of free memory in the dialog, and the same check runs on Ctrl-R so a refresh that errored out can no longer look like a successful one. - Data connections shrink to fit instead of failing. The 16 KB receive buffer is halved until it can be allocated (down to the configured minimum), so a tight machine transfers more slowly rather than not at all. The XMS/EMS listing store does the same with its index table, keeping thousands of entries usable where the whole store used to be discarded.
- The panel's conventional buffer is allocated only when it is used. It is a ~30 KB array that sat in both panes even though the remote one normally runs on XMS/EMS — that half was reserved and never touched. It is now taken on first use, which gives the memory back to the machines that need it most.
- "Check MTCPCFG" is no longer the answer to every startup failure. Out of memory is told apart from a broken configuration and reported as what it is, including the free-memory figure.
- Cancelling a transfer returns immediately. Esc during a download could
freeze for ~30 s: a server that keeps streaming never answers a plain in-band
ABOR, so the full control timeout ran out. The wait for that answer is now bounded and overlaps the socket close, while the data connection keeps being drained so the receive window never shuts. Never visible in the test VM, where the server answers at once. - Throughput tuning for fast links at the default MTU (reported from real hardware: 753 KB/s at MTU 576 against 11 MB/s at 1500). More packet buffers (40 instead of 20) and a bigger per-socket ring (16, the value Brutman's own throughput benchmark uses), because at a small MSS the same number of bytes arrives as 2.7x as many packets and the old ring covered about a millisecond.
- Downloading several marked files no longer collapses them onto one name.
Long names sharing their first six characters and extension mangle to the
same 8.3 name (
Dateiname1.txtandDateiname2.txtboth becameDATEIN~1.TXT), so each file overwrote the last while the overwrite prompt named a remote file that was not there yet. Names are now made unique within the batch — but still never against the disk, so re-downloading the same file keeps hitting the same target and its overwrite prompt. - New
/LD:DIR— the local counterpart of/D:. Opens the left pane in a directory, a drive, or both (/LD:D:,/LD:D:\DOWNLOAD). A path that does not exist is reported once and the program carries on rather than aborting. /LASTCONon a connection saved without its password now opens the connect dialog with everything else filled in, instead of sending an empty password and failing the login. Anonymous logins still go straight in.