VRAM access timing - Revision history

Aoineko: /* Reference machines */

2026-04-06T19:36:25Z

‎Reference machines

Aoineko: /* Reference machines */

2024-12-10T23:45:37Z

‎Reference machines

Aoineko: /* Reference machines */

2024-12-10T23:45:07Z

‎Reference machines

Aoineko: /* VDP command (V9938/58) */

2024-09-25T07:45:22Z

‎VDP command (V9938/58)

Aoineko: /* VDP command (V9938/58) */

2024-09-25T07:43:02Z

‎VDP command (V9938/58)

Aoineko: /* Annexes */

2024-09-21T18:43:44Z

‎Annexes

Aoineko: /* No screen display */

2024-09-11T21:48:49Z

‎No screen display

Aoineko: /* Reference machines */

2024-06-14T22:40:51Z

‎Reference machines

Aoineko at 14:34, 2 March 2024

2024-03-02T14:34:27Z

Aoineko: /* Default */

2023-11-12T23:21:45Z

‎Default

@@ Line 171: / Line 171: @@
 | Panasonic FS-A1       || MSX2       || Yamaha V9938                 || NTSC   ||
 |-
-| ''Panasonic FS-A1FX'' || MSX2+      || Yamaha V9958                 || NTSC   || I/O +2 t-states
+| ''Panasonic FS-A1FX'' || MSX2+      || Yamaha V9958                 || NTSC   || I/O +1 t-state
 |-
 | ''Panasonic FS-A1GT'' || MSX turbo R || Yamaha V9958                 || NTSC   || I/O +1 t-state

← Older revision		Revision as of 23:45, 10 December 2024
Line 207:		Line 207:
	In italics, machines with only a partial result (test performed with an older version of VATT).		In italics, machines with only a partial result (test performed with an older version of VATT).

		+	=== Raw data ===
	Database with all result can be found there: https://docs.google.com/spreadsheets/d/16uGdJ7JT1MWZ4qQLUDrGk1Wfw3w_EbaMpoS_fxeSJuI/edit?usp=sharing		Database with all result can be found there: https://docs.google.com/spreadsheets/d/16uGdJ7JT1MWZ4qQLUDrGk1Wfw3w_EbaMpoS_fxeSJuI/edit?usp=sharing

← Older revision		Revision as of 23:45, 10 December 2024
Line 208:		Line 208:

	Database with all result can be found there: https://docs.google.com/spreadsheets/d/16uGdJ7JT1MWZ4qQLUDrGk1Wfw3w_EbaMpoS_fxeSJuI/edit?usp=sharing		Database with all result can be found there: https://docs.google.com/spreadsheets/d/16uGdJ7JT1MWZ4qQLUDrGk1Wfw3w_EbaMpoS_fxeSJuI/edit?usp=sharing
		+
		+	<html><iframe class="inlineCodeDoc" id="vatt_data"
		+	width="100%"
		+	height="700px"
		+	title="Inline Code Documentation"
		+	src="https://docs.google.com/spreadsheets/d/16uGdJ7JT1MWZ4qQLUDrGk1Wfw3w_EbaMpoS_fxeSJuI/edit?usp=sharing">
		+	</iframe></html>

@@ Line 123: / Line 123: @@
 If you have previously started commands on this VRAM area and you are not sure if they are finished, it is recommended to use the <tt>VDP_CommandWait()</tt> function before starting direct access to that area.
-Note that the execution time of VDP commands is also influenced by the same context elements as VRAM direct access times: screen display, sprite display, v-blank, etc. But unlike direct access, which can fail, the only issue with VDP commands is the time they take to execute. More info here: https://map.grauw.nl/articles/vdp_commands_speed.php
+<u>Note</u>: Execution time of VDP commands is also influenced by the same context elements as VRAM direct access times: screen display, sprite display, v-blank, etc. But unlike direct access, which can fail, the only issue with VDP commands is the time they take to execute (and how to optimize code to take advantage of it). More info here: https://map.grauw.nl/articles/vdp_commands_speed.php
 === Emulation ===

← Older revision		Revision as of 07:43, 25 September 2024
Line 122:		Line 122:

	If you have previously started commands on this VRAM area and you are not sure if they are finished, it is recommended to use the <tt>VDP_CommandWait()</tt> function before starting direct access to that area.		If you have previously started commands on this VRAM area and you are not sure if they are finished, it is recommended to use the <tt>VDP_CommandWait()</tt> function before starting direct access to that area.
		+
		+	Note that the execution time of VDP commands is also influenced by the same context elements as VRAM direct access times: screen display, sprite display, v-blank, etc. But unlike direct access, which can fail, the only issue with VDP commands is the time they take to execute. More info here: https://map.grauw.nl/articles/vdp_commands_speed.php

	=== Emulation ===		=== Emulation ===

@@ Line 140: / Line 140: @@
 Some examples:
 {|
-| {{IMG|raw.githubusercontent.com/aoineko-fr/VATT/master/doc/benchmark/nms8250_sc1_sp1_cm0.jpg|height:200px|Philips NMS8250}}
+| {{IMG|raw.githubusercontent.com/aoineko-fr/VATT/master/doc/benchmark/nms8250_sc1_sp1_cm0.jpg|height:200px|Philips NMS 8250}}
 | {{IMG|raw.githubusercontent.com/aoineko-fr/VATT/master/doc/benchmark/fsa1_rom.jpg|height:200px|Panasonic FS-A1}}
 |}

@@ Line 83: / Line 83: @@
 | Graphic 7  || Screen 8           || --      || ≤12
 |}
 === No sprite display (V9938/58) ===

@@ Line 169: / Line 169: @@
 | ''Panasonic FS-A1FX'' || MSX2+      || Yamaha V9958                 || NTSC   || I/O +2 t-states
 |-
-| ''Panasonic FS-A1GT'' || MSXturbo R || Yamaha V9958                 || NTSC   || I/O +1 t-state
+| ''Panasonic FS-A1GT'' || MSX turbo R || Yamaha V9958                 || NTSC   || I/O +1 t-state
 |-
 | ''Philips NMS 8245'' (modded) || MSX2 || Yamaha V9958               || PAL    ||

@@ Line 11: / Line 11: @@
 A tool was then created to verify these theoretical access times with concrete test cases: [https://github.com/aoineko-fr/VATT VATT] (for VRAM Access Timing Tester).
-The results of these tests showed that the reference data had some limitations. Notably a wrong access time for Screen Mode 3 on MSX 1 (TMS9918) or an unexpected effect with screen disabling for non-bitmap modes on MSX 2 (V9938/58).
+The results of these tests showed that the reference data had some limitations. Notably a wrong access time for Screen Mode 3 on MSX1 (TMS9918) or an unexpected effect with screen disabling for non-bitmap modes on MSX2 (V9938/58).
 These results have yet to be confirmed with other tests, but they have highlighted worst-case scenarios that we need to consider.
@@ Line 29: / Line 29: @@
 === Default ===
-The default condition is when Screen display is activated. On MSX 2 or above, the Sprite display is also activated.
+The default condition is when Screen display is activated. On MSX2 or above, the Sprite display is also activated.
 {| class="wikitable"
@@ Line 55: / Line 55: @@
 |}
-<u>Note:</u> For MSX 1, VATT results have shown that an access time of 27 t-states generates no errors and can be considered safe (tests represent over 1.6 million bytes sent in VRAM without a single error on 17 different MSX 1). However, as we are not sure that we have tested all existing MSX VDPs, we have chosen to be conservative for MSXgl and keep the maximum access time at 29 t-states.
+<u>Note:</u> For MSX1, VATT results have shown that an access time of 27 t-states generates no errors and can be considered safe (tests represent over 1.6 million bytes sent in VRAM without a single error on 17 different MSX1). However, as we are not sure that we have tested all existing MSX VDPs, we have chosen to be conservative for MSXgl and keep the maximum access time at 29 t-states.
 === No screen display ===
@@ Line 147: / Line 147: @@
 ! Machine               !! BIOS        !! VDP                          !! Region !! Misc.
 |-
-| Canon V-8             || MSX 1       || Texas Instruments TMS9118NL  || NTSC   ||
+| Canon V-8             || MSX1       || Texas Instruments TMS9118NL  || NTSC   ||
 |-
-| ''Canon V-20''        || MSX 1       || Texas Instruments	TMS9918ANL || NTSC   ||
+| ''Canon V-20''        || MSX1       || Texas Instruments	TMS9918ANL || NTSC   ||
 |-
-| Casio MX-10           || MSX 1       || Texas Instruments TMS9118NL  || NTSC   ||
+| Casio MX-10           || MSX1       || Texas Instruments TMS9118NL  || NTSC   ||
 |-
-| Casio MX-101          || MSX 1       || Texas Instruments TMS9118NL  || NTSC   ||
+| Casio MX-101          || MSX1       || Texas Instruments TMS9118NL  || NTSC   ||
 |-
-| ''Casio PV-7''        || MSX 1       || Texas Instruments TMS9118NL  || NTSC   ||
+| ''Casio PV-7''        || MSX1       || Texas Instruments TMS9118NL  || NTSC   ||
 |-
-| Gradiente Expert GPC-1 || MSX 1      || Texas Instruments TMS9128NL  || NTSC   ||
+| Gradiente Expert GPC-1 || MSX1      || Texas Instruments TMS9128NL  || NTSC   ||
 |-
-| Hitachi MB-H1         || MSX 1       || Texas Instruments TMS9918ANL || NTSC   ||
+| Hitachi MB-H1         || MSX1       || Texas Instruments TMS9918ANL || NTSC   ||
 |-
-| Mitsubishi ML-8000    || MSX 1       || Texas Instruments TMS9918ANL || NTSC   ||
+| Mitsubishi ML-8000    || MSX1       || Texas Instruments TMS9918ANL || NTSC   ||
 |-
-| National CF-2700      || MSX 1       || Texas Instruments TMS9918A   || NTSC   ||
+| National CF-2700      || MSX1       || Texas Instruments TMS9918A   || NTSC   ||
 |-
-| Panasonic FS-A1       || MSX 2       || Yamaha V9938                 || NTSC   ||
+| Panasonic FS-A1       || MSX2       || Yamaha V9938                 || NTSC   ||
 |-
-| ''Panasonic FS-A1FX'' || MSX 2+      || Yamaha V9958                 || NTSC   || I/O +2 t-states
+| ''Panasonic FS-A1FX'' || MSX2+      || Yamaha V9958                 || NTSC   || I/O +2 t-states
 |-
-| ''Panasonic FS-A1GT'' || MSX turbo R || Yamaha V9958                 || NTSC   || I/O +1 t-state
+| ''Panasonic FS-A1GT'' || MSXturbo R || Yamaha V9958                 || NTSC   || I/O +1 t-state
 |-
-| ''Philips NMS 8245'' (modded) || MSX 2 || Yamaha V9958               || PAL    ||
+| ''Philips NMS 8245'' (modded) || MSX2 || Yamaha V9958               || PAL    ||
 |-
-| Philips NMS 8250      || MSX 2       || Yamaha V9938                 || PAL    ||
+| Philips NMS 8250      || MSX2       || Yamaha V9938                 || PAL    ||
 |-
-| Sanyo MPC-2           || MSX 1       || Toshiba T6950                || NTSC   ||
+| Sanyo MPC-2           || MSX1       || Toshiba T6950                || NTSC   ||
 |-
-| Sanyo MPC-3           || MSX 1       || Texas Instruments TMS9118NL  || NTSC   ||
+| Sanyo MPC-3           || MSX1       || Texas Instruments TMS9118NL  || NTSC   ||
 |-
-| Sharp HB-8000 (v1.1)  || MSX 1       || Texas Instruments TMS9128NL  || NTSC   ||
+| Sharp HB-8000 (v1.1)  || MSX1       || Texas Instruments TMS9128NL  || NTSC   ||
 |-
-| Sharp HB-8000 (v1.2)  || MSX 1       || Texas Instruments TMS9128NL  || NTSC   ||
+| Sharp HB-8000 (v1.2)  || MSX1       || Texas Instruments TMS9128NL  || NTSC   ||
 |-
-| Sony HB-75P           || MSX 1       || Texas Instruments TMS9929    || NTSC   ||
+| Sony HB-75P           || MSX1       || Texas Instruments TMS9929    || NTSC   ||
 |-
-| ''Sony HB-F1XD''      || MSX 2       || Yamaha V9938                 || NTSC   ||
+| ''Sony HB-F1XD''      || MSX2       || Yamaha V9938                 || NTSC   ||
 |-
-| ''Sony HB-F1XD''      || MSX 2       || Yamaha V9938                 || NTSC   ||
+| ''Sony HB-F1XD''      || MSX2       || Yamaha V9938                 || NTSC   ||
 |-
-| Sony HB-F500 (rev2)   || MSX 2       || Yamaha V9938                 || NTSC   ||
+| Sony HB-F500 (rev2)   || MSX2       || Yamaha V9938                 || NTSC   ||
 |-
-| Toshiba HX-10DP       || MSX 1       || Texas Instruments TMS9918A   || NTSC   ||
+| Toshiba HX-10DP       || MSX1       || Texas Instruments TMS9918A   || NTSC   ||
 |-
-| Toshiba HX-21         || MSX 1       || Texas Instruments TMS9928A   || NTSC   ||
+| Toshiba HX-21         || MSX1       || Texas Instruments TMS9928A   || NTSC   ||
 |-
-| ''Victor HC-30''      || MSX 1       || Yamaha YM2220                || NTSC   ||
+| ''Victor HC-30''      || MSX1       || Yamaha YM2220                || NTSC   ||
 |-
-| ''Yamaha CX5MII''     || MSX 1       || Yamaha V9938                 || PAL    ||
+| ''Yamaha CX5MII''     || MSX1       || Yamaha V9938                 || PAL    ||
 |}