mirror of
https://git.k-space.ee/arti/vt1200.git
synced 2026-11-02 12:23:17 +02:00
arti
d8d54bb990
The XIE path now runs end to end: XieCreateImage -> XieCreatePhoto ->
XiePutTile -> XieExport(photomap -> depth-1 pixmap) -> XCopyArea(pixmap ->
window), and the client's tile appears on screen at the client's own window
position, pixel-exact.
TWO FAULTS BEHIND THE LONG DEAD END
1. Device model (harness/mame/vt1200.cpp, opt-in VT1200_ACCEL=1). The
accelerator's output port 0x5600200 returns the pixel stream the firmware
pushed into the FIFO -- the firmware then stores it into the drawable itself
(file 0x125528: MOVE *B6,*B1 ; ADDK 0x10,B1). The FIFO read pointer was
never reset between transfers, so consecutive exports read stale words and
the same fill produced 759 then 516 set pixels. Reset m_fifo_in/out on the
data-register write; the export is now deterministic.
2. Measurement, not the device.
- dwt/screenshot.py without --real reads 1024x1024 at a 128-byte row stride,
but the VR319 default programs 1280x1024 at a 2048-bit (256-byte) pitch.
That is the "shifted" picture; --real is the correct read.
- The earlier "0 differing bytes over 128 KiB" VRAM comparison stepped peek
by 1024 *bit* addresses, so it scanned rows 0..63 only -- never the window
at rows 200..263. Over the real raster the white/black diff is 576 bytes
spanning exactly those rows.
- New instrument: decclient does a server-side XGetImage readback of the
pixmap and window and counts set pixels. That separated "the server never
drew it" from "the framebuffer view is wrong".
EVIDENCE (reproduced twice, the second time from a fresh machine)
no export vs 0xFF : 4096 / 4096 pixels differ
no export vs 0x00 : 0 / 4096 (the window background is black)
0xFF vs 0x00 : 4096 / 4096
0xAA vs 0x0F : 2048 / 4096 (the two stripe phases)
Tile byte 0xAA reproduces as 1-pixel vertical stripes, 0x0F as 4-pixel, with
no shear -- so the placement is right and the pixels are the client's.
Contents: xie/ holds DEC XIE 2.3 headers, 84 man pages and complete
client+server source; a libXie.a and decclient built from DEC's own code; the
XIE probes; and evidence/ with every measurement, including explicit
retractions of the earlier wrong readings (VRAM_IDENTICAL_FOR_BOTH_FILLS and
friends). xie/evidence/XIE_IMAGE_DISPLAYED.md is the report; frames are in
xie/evidence/png/.
The accelerator model stays opt-in: it answers the status poll and relays the
pixel stream, but performs no compositing, so it is a stand-in and the verified
default configuration is unchanged (a no-env run still parks in the level-0
diagnostics menu at PC=3FDCE400).
X Consortium XIE specification (DECUS LT92A, X11R4 contrib)
Fetched from
https://www.digiater.nl/openvms/decus/lt92a/x11r4/contrib/doc/xie/
on 2026-11-01:
| file | contents |
|---|---|
concepts.ps / .txt |
XIE Concepts |
protocol.ps / .txt |
XIE Protocol Specification, v2.0 (with v2.1 field-test notes) |
server.ps / .txt |
XIE Server interpretation |
(.ps are the originals; .txt produced with ps2pdf + pdftotext -layout.)
These are NOT the VT1200's XIE
Measured discriminator: the VT1200 firmware is the DEC photoflo lineage, while these documents are the X Consortium lineage. Counts in the extracted text:
file pipeline photoflo IOB
protocol 80 0 350
concepts 27 0 22
server 3 0 210
photoflo appears zero times in all three. The two lineages differ in vocabulary
and, more importantly, in resource model:
| this spec (X Consortium v2.0) | VT1200 (DEC XIE 2.3) |
|---|---|
XIEP_EXECUTE_PIPE |
XIEP_EXECUTE_PHOTOFLO |
BINDING |
XIEP_BIND_PHOTOFLO |
| resources: IOB / IDC / IPC | photoflo + image resources |
XIEP_CREATE_RESOURCE, XIEP_IMPORT_IMAGE, XIEP_EXPORT_IMAGE |
XIEP_CREATE_BY_VALUE, XIEP_EXPORT |
The firmware's own strings settle it — reference/rom-strings.txt and the XIE module
contain "error allocating photoflo", CROP/MIRROR/ROTATE/SCALE/EXPORT Process block, and error: unsupported pipe element. Those are photoflo/process-block terms,
matching docs/EK-V120I-IN-001_installing-DECimage-1200.txt Appendix C, not this spec.
What these documents are still good for
- the general XIE shape (transport services, pipelines, export producing a PIXMAP, error classes) — useful for orientation and for confirming inferences;
- Appendix 9.4.1 "Conceptual Changes" explains the split (server-side rendition + named contexts moved to protocol parameters), which is why the vocabularies diverge;
- not useful for: minor-opcode numbers or wire field layouts. This spec states outright that it carries no language bindings (line 272) and it contains no request/opcode numbering — that lives in the server headers.
Still missing
The VT1200's wire format needs the DEC XIE 2.3 headers/library
(XIEproto.h, xie.h, libXIE 2.3 — the DECimage Application Services media), not
the X Consortium specification.