ASIC - Revision history

Phi2x at 17:25, 14 May 2025

2025-05-14T17:25:49Z

2025-05-13T19:59:25Z

‎Amstrad custom chips

2025-05-13T19:59:00Z

‎Amstrad custom chips

2025-05-13T14:06:18Z

‎Emulated chips

2025-05-13T14:02:03Z

‎Emulated chips

2025-04-05T13:07:07Z

‎Known flaws

2025-04-05T05:17:23Z

‎Known flaws

2025-04-05T04:18:50Z

‎ASIC I/O page

2025-02-16T10:50:41Z

‎Hardware sprites

2025-02-16T08:36:15Z

‎ASIC I/O page

← Older revision		Revision as of 17:25, 14 May 2025
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		+	[[File:Amstrad.40489.asic.jpg\|thumb\|right\|Amstrad Plus ASIC]]
		+
	'''Application-Specific Integrated Circuit''' (ASIC)		'''Application-Specific Integrated Circuit''' (ASIC)

@@ Line 11: / Line 11: @@
 ==Amstrad custom chips==
-The Amstrad CPC used one custom chip: the video [[Gate Array]] (also called VGA – no connection with the Video PC standard).
+The Amstrad CPC used one custom chip: the Video Gate Array (also called VGA – no connection with the Video PC standard).
 Later [[CPC]] cost down series included a "pre-ASIC" chip to merge the [[Gate Array]] and the [[CRTC]].

@@ Line 13: / Line 13: @@
 The Amstrad CPC used one custom chip: the video [[Gate Array]] (also called VGA – no connection with the Video PC standard).
-Later [[CPC]] cost down series included a "pre-ASIC"-called ASIC to merge the VGA and the [[CRTC]].
+Later [[CPC]] cost down series included a "pre-ASIC" chip to merge the [[Gate Array]] and the [[CRTC]].
 The Amstrad [[Plus]] included a "second heart" simply referred as the ASIC.

@@ Line 32: / Line 32: @@
 * Floppy Motor enable [[flip-flop]], Floppy Address decoding (FDC chip Select)
-The ASIC has a configuration resistor (R128) distinguishing between 128K and 64K mainboards. It disables the PAL component on the 464 Plus and GX4000. [https://www.cpcwiki.eu/forum/news-events/announcing-sonic-gx-a-new-episode-of-sonic-the-hedgehog-for-amstrad-gx-4000/msg248436/#msg248436 Source]
+The ASIC has a configuration resistor (R128) distinguishing between 6128 Plus and other mainboards. It disables the AMSDOS ROM mapping and the PAL component on the 464 Plus and GX4000. [https://www.cpcwiki.eu/forum/news-events/announcing-sonic-gx-a-new-episode-of-sonic-the-hedgehog-for-amstrad-gx-4000/msg248436/#msg248436 Source]
 <br>

@@ Line 31: / Line 31: @@
 * Printer Port Data and Strobe
 * Floppy Motor enable [[flip-flop]], Floppy Address decoding (FDC chip Select)
 <br>

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 *Reducing horizontal blanking could cause another internal conflict when using DMA lists. In the worst case, this conflict can cause irreversible damage to the ASIC.
-*Original CPC colors emulation is not correct.
+*Original CPC colours are slightly different.
 <br>

@@ Line 215: / Line 215: @@
 The Amstrad Plus ASIC improved a lot of the old CPC's capability.
 Yet this was a bit flawed.
 *PPI emulation is not correct as the original 8255 does not need validation. On ASIC emulation, this validation is needed so some programs written for "old CPCs" will not be able to get keyboard state.

@@ Line 357: / Line 357: @@
 Beware, when booting your software from cartridge. Z80 is in Interrupt Mode 0 by default. Stack Pointer is uninitialized. FDC is in DMA mode by default. And hardware sprites memory has random value.
-Anyway, you have to initialize all internal components (Z80, PPI, CRTC, AY, etc) when you are booting from cartridge.
+Anyway, you have to initialize all internal components when you are booting from cartridge.
 <br>

← Older revision		Revision as of 10:50, 16 February 2025
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	Sprites will be displayed at coordinates based on the internal counters of the CRTC. Sprite X coordinate is based on HCC. Sprite Y coordinate is based on VCC and VLC.		Sprites will be displayed at coordinates based on the internal counters of the CRTC. Sprite X coordinate is based on HCC. Sprite Y coordinate is based on VCC and VLC.
		+
		+	When the data for a sprite is read or written, that sprite is removed from the display for the duration of the access. Thus sprite data should only be accessed during retraced time or while the raster is scanning somewhere else, otherwise there is a risk of disruption of the display. [[Original Arnold V Specs\|Source]]

	<br>		<br>

← Older revision		Revision as of 08:36, 16 February 2025
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	POR column indicates whether a register has power-on reset. A "N" indicates that the contents of a register are undefined at power-on.		POR column indicates whether a register has power-on reset. A "N" indicates that the contents of a register are undefined at power-on.

		+	Writes to unused areas of the ASIC I/O page are not persisted. [https://www.cpcwiki.eu/forum/games/harrier-attack-reloaded/msg247703/#msg247703 Source]

	Beware, when booting your software from cartridge. Z80 is in Interrupt Mode 0 by default. Stack Pointer is uninitialized. FDC is in DMA mode by default. And hardware sprites memory has random value.		Beware, when booting your software from cartridge. Z80 is in Interrupt Mode 0 by default. Stack Pointer is uninitialized. FDC is in DMA mode by default. And hardware sprites memory has random value.