Connecting a Disc Interface to CPC464+ - Revision history

MacDeath at 01:41, 17 December 2010

2010-12-17T01:41:05Z

Nocash: /* System Cartridge Bug */

2010-03-26T12:26:22Z

‎System Cartridge Bug

Bryce at 12:08, 19 March 2010

2010-03-19T12:08:53Z

Nocash at 09:57, 17 March 2010

2010-03-17T09:57:07Z

Nocash: /* System Cartridge Bug */

2010-03-16T23:27:25Z

‎System Cartridge Bug

Nocash: /* System Cartridge Bug */

2010-03-16T23:23:09Z

‎System Cartridge Bug

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Nocash: /* System Cartridge Bug */

2010-03-16T23:17:33Z

‎System Cartridge Bug

Nocash: /* System Cartridge Bug */

2010-03-16T23:16:40Z

‎System Cartridge Bug

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Nocash at 23:15, 16 March 2010

2010-03-16T23:15:19Z

Nocash: Created page with 'Basically, the official DDI-1 and any other third-party disc interfaces for the CPC 464 should work on the CPC 464 as well. However, there are two problems…'

2010-03-16T23:03:20Z

Created page with 'Basically, the official DDI-1 and any other third-party disc interfaces for the CPC 464 should work on the CPC 464 as well. However, there are two problems…'

New page

Basically, the official [[Amstrad Disk Drive|DDI-1]] and any other third-party disc interfaces for the CPC 464 should work on the CPC 464 as well. However, there are two problems:

== Expansion Port ==

The CPC464 used a 50pin edge-connector, the CPC464+ uses a 50pin centronics-style connector. The pin-outs are identical, so this problem can be solved with a simple adapter. Equivalent adapters do also exist for the german CPC6128 (which has a 50pin centronics-style expansion port, too).

== System Cartridge Bug ==

There is a bug in the system cartridge, that causes the BIOS to execute code at C072h in ROM bank 07h. Normally, the AMSDOS bank in the system cartridge contains the Burnin' Rubber bootmenu at that location. However, this works only if the CPC+'s built-in AMSDOS is mapped to bank 07h.

When using an external disk-interface with external AMSDOS ROM (or other DOS clone), executing code at C072h is typically crashing the computer. The same problem occurs when activating the CP/M autoboot feature via [[LK Links]] (which swaps bank 0 and 7). Possible workarounds are:

* Replace opcode LD C,07h (at 05EBh in system cart) by LD C,83h (this fixes the bug)
* Replace opcode LD HL,C072h (at 05E8h in system cart) by LD HL,0000h (completely disables the bootmenu, which was a rather idea annoying anyways)
* Or, remove or disable the ROM in the disc-interface, and cut the ROMDIS signal in the disc-interface (so the built-in AMSODS in the CPC+ is used; this can be done without EPROM burner, but doesn't support 80-track drives)

← Older revision		Revision as of 01:41, 17 December 2010
Line 1:		Line 1:
		+	[[Category:DATA Storage]][[Category:DIY]]
	== External Disc Interface ==		== External Disc Interface ==

@@ Line 17: / Line 17: @@
 * Remove or disable the ROM in the disc-interface, and cut the ROMDIS signal in the disc-interface (so the built-in AMSDOS in the CPC+ is used instead of the external DOS; this can be done without EPROM burner, but doesn't support 80-track drives)
 * Use an external DOS that resides elsewhere than in ROM bank 7 (whereas, the external DOS must undo hooks and memory allocations done by the internal AMSDOS; this should be supported by ParaDOS)
-* Insert two opcodes (LD HL,0000h, JP BD16h) at C072h in the DOS ROM (so the CPC+ "returns" from the bootmenu without crashing)
+* Insert two opcodes (LD HL,0000h, JP BD16h) at C072h in the DOS ROM (so the CPC+ "returns" from the bootmenu without crashing) (this is supported by ParaDOS, using a similar slightly different method)
 * etc.

@@ Line 5: / Line 5: @@
 === Expansion Port Adapter ===
-The CPC464 used a 50pin edge-connector, the CPC464+ uses a 50pin centronics-style connector. The pin-outs are identical, so this problem can be solved with a simple adapter. Equivalent adapters do also exist for the german CPC6128 (which has a 50pin centronics-style expansion port, too).
+The CPC464 used a 50pin edge-connector, the CPC464+ uses a 50pin centronics-style connector. The pin-outs are identical, so this problem can be solved with a simple adapter. Equivalent adapters do also exist for the german CPC6128 (which has a 50pin centronics-style expansion port, too): [[Expansion Converter|UK/DE Expansion Converter]].
 === System Cartridge Bug ===

@@ Line 1: / Line 1: @@
 Basically, the official [[Amstrad Disk Drive|DDI-1]] and any other third-party disc interfaces for the CPC 464 should work on the CPC 464+ as well. However, there are two problems:
-== Expansion Port Adapter ==
+=== Expansion Port Adapter ===
 The CPC464 used a 50pin edge-connector, the CPC464+ uses a 50pin centronics-style connector. The pin-outs are identical, so this problem can be solved with a simple adapter. Equivalent adapters do also exist for the german CPC6128 (which has a 50pin centronics-style expansion port, too).
-== System Cartridge Bug ==
+=== System Cartridge Bug ===
 There is a bug in the system cartridge, that causes the BIOS to execute code at C072h in ROM bank 07h. Normally, the AMSDOS bank in the system cartridge contains the Burnin' Rubber bootmenu at that location. However, this works only if the CPC+'s built-in AMSDOS is mapped to bank 07h.
@@ Line 17: / Line 19: @@
 * Insert two opcodes (LD HL,0000h, JP BD16h) at C072h in the DOS ROM (so the CPC+ "returns" from the bootmenu without crashing)
 * etc.

← Older revision		Revision as of 23:27, 16 March 2010
Line 15:		Line 15:
	* Remove or disable the ROM in the disc-interface, and cut the ROMDIS signal in the disc-interface (so the built-in AMSDOS in the CPC+ is used instead of the external DOS; this can be done without EPROM burner, but doesn't support 80-track drives)		* Remove or disable the ROM in the disc-interface, and cut the ROMDIS signal in the disc-interface (so the built-in AMSDOS in the CPC+ is used instead of the external DOS; this can be done without EPROM burner, but doesn't support 80-track drives)
	* Use an external DOS that resides elsewhere than in ROM bank 7 (whereas, the external DOS must undo hooks and memory allocations done by the internal AMSDOS; this should be supported by ParaDOS)		* Use an external DOS that resides elsewhere than in ROM bank 7 (whereas, the external DOS must undo hooks and memory allocations done by the internal AMSDOS; this should be supported by ParaDOS)
		+	* Insert two opcodes (LD HL,0000h, JP BD16h) at C072h in the DOS ROM (so the CPC+ "returns" from the bootmenu without crashing)
		+	* etc.

@@ Line 13: / Line 13: @@
 * Replace opcode LD C,07h (at 05EBh in system cart) by LD C,83h (this fixes the bug)
 * Replace opcode LD HL,C072h (at 05E8h in system cart) by LD HL,0000h (completely disables the bootmenu, which was a rather annoying idea anyways)
-* Or, remove or disable the ROM in the disc-interface, and cut the ROMDIS signal in the disc-interface (so the built-in AMSDOS in the CPC+ is used instead of the external DOS; this can be done without EPROM burner, but doesn't support 80-track drives)
+* Remove or disable the ROM in the disc-interface, and cut the ROMDIS signal in the disc-interface (so the built-in AMSDOS in the CPC+ is used instead of the external DOS; this can be done without EPROM burner, but doesn't support 80-track drives)

@@ Line 12: / Line 12: @@
 * Replace opcode LD C,07h (at 05EBh in system cart) by LD C,83h (this fixes the bug)
-* Replace opcode LD HL,C072h (at 05E8h in system cart) by LD HL,0000h (completely disables the bootmenu, which was a rather idea annoying anyways)
+* Replace opcode LD HL,C072h (at 05E8h in system cart) by LD HL,0000h (completely disables the bootmenu, which was a rather annoying idea anyways)
 * Or, remove or disable the ROM in the disc-interface, and cut the ROMDIS signal in the disc-interface (so the built-in AMSODS in the CPC+ is used; this can be done without EPROM burner, but doesn't support 80-track drives)