diff --git a/docs/NOTES-TESTING-LOG/2018-07-05/TEST RESULTS AND FINDINGS.TXT b/docs/NOTES-TESTING-LOG/2018-07-05/TEST RESULTS AND FINDINGS.TXT deleted file mode 100644 index 5d8b93850..000000000 --- a/docs/NOTES-TESTING-LOG/2018-07-05/TEST RESULTS AND FINDINGS.TXT +++ /dev/null @@ -1,98 +0,0 @@ -2018/07/02 test results and findings. - -Test units: - -COMP-IBMPS2-30 An old IBM PS/2 Model 30 (286) with VGA -DOSLIB-d7d079bfd75a71b4c4d5b2afc9efc5e69cefa152 DOSLIB, by indicated commit - -Equipment: - - - HDMI video capture (PEXHDCAP 1080p30) - - - VGA to HDMI adapter (one that matches the mode and converts as-is) - -Software: - - - DOSLIB build: - git commit 848166fcacb6292773253273ef192ddae7942064 - -Findings: - - - VGA DAC test program shows straightforward attribute controller translation, as if - the 8-bit value is split into two 4-bit nibbles and translated on it's way through - the AC palette. - - - Switching off 8BIT in the attribute controller shows a strange sort of 640x200 - 256-color mode, except that each pixel displayed looks as if half the value sent - to the DAC is loaded per pixel clock before becoming the full 8-bit value. - - It's not certain yet whether the nibble value is loaded in or shifted in. - - It's not certain yet which nibble is loaded first. - - - Switching on the 8BIT in the attribute controller for any other video mode seems - to halve the video resolution without any other effects. - - - The "MONO" bit, listed on FreeVGA as apparently doing nothing, appears to influence - how the blink attribute is applied on it's way to the DAC. - - - On an IBM PS/2 model 30 (VGA), the blink attribute can be switched on in any VGA - graphics mode, which then acts on bit 3 in all modes except 256-color mode where it - affects bit 3 and bit 7 (possibly related to the 4-bit 256-color shift behavior listed - above). - - - If MONO=0, and graphics mode, the blink attribute in graphics mode seems to remap like this: - - if (color >= 8) { - color = (color & 7) + (blink << 3); - } - else { - color |= 8; - } - - - If MONO=1, or alphanumeric (text) mode, the blink attribute in graphics mode seems to remap like this: - - color = (color & 7) + (blink << 3); - - - Noted, according to VGA register snapshots, is that the BIOS sets MONO=0 for all modes except - mode 7 (80x25 mono text) and mode 15 (640x350 2-color graphics) where MONO=1. - - -Other ideas to follow: - - - Jim Leonard on Twitter wants to know if the vertical retrace interrupt works. - - Ref: https://twitter.com/MobyGamer/status/1015097180883955712 - - Ref: https://www.vogons.org/viewtopic.php?t=58445 - - -Questions to answer in further development: - - - Is the blink attribute applied before or after the attribute palette remapping? - - - What nibble is loaded first when 8BIT=0 in 256-color mode? - - - What other VGA cards does this 256-color 8BIT=0 behavior occur, or more specifically, - what do clone cards do in this case? - - - Is the value simply replaced a nibble at a time or is it shifted 4 bits and loaded? - - - The Tseng ET4000, known to replace only the low 4 bits, should be re-tested with the - new code and to see what odd behaviors it has. - - - Do other SVGA cards remap through the attribute controller in a way that the blink - attribute can affect the output in any mode? - - - Regarding the vertical retrace interrupt, does it work on the PS/2? - - - What other SVGA cards does the vertical retrace interrupt work on? - - - Do these SVGA cards work as documented, or do they ignore certain behaviors, act different, - etc? - -Ideas for further development: - - - DOSLIB VGA test program to demonstrate vertical retrace interrupt, whether it's occurring, - whether it works as documented. -