C't 512 KB internal RAM expansion - Revision history

Eto at 14:10, 19 July 2023

2023-07-19T14:10:50Z

← Older revision		Revision as of 14:10, 19 July 2023
Line 94:		Line 94:
	== Related hardware modifications ==		== Related hardware modifications ==

	* [~~http~~://cpcwiki.eu/forum/index.php/topic,662.msg7113.html#msg7113 Bank Swapper by Khany/Cherry-T] (less complex: bank-exchanging toggle, no memory expansion; 1993)		* [[CPC_6320_/_CPC_6512_-_internal_320K_/_512K_for_CPC_6128\|CPC 6320 / CPC 6512 (by eto) - similar logic, but fully standards compatible]]
			* [https://cpcwiki.eu/forum/index.php/topic,662.msg7113.html#msg7113 Bank Swapper by Khany/Cherry-T] (less complex: bank-exchanging toggle, no memory expansion; 1993)
	* [[CPC4MB\| CPC4MB memory upgrade by Yarek]] (more advanced; 2005/2006)		* [[CPC4MB\| CPC4MB memory upgrade by Yarek]] (more advanced; 2005/2006)

MacDeath at 01:23, 17 December 2010

2010-12-17T01:23:53Z

← Older revision		Revision as of 01:23, 17 December 2010
Line 1:		Line 1:
	[[Category:DIY]]		[[Category:DIY]] [[Category:Memory expansions]]
	A project to upgrade a CPC6128 to 512K RAM (total), done by replacing the CPC6128's RAM chips, and its PAL banking chip, the project was released 1987 in german magazine ''c't Magazin''.		A project to upgrade a CPC6128 to 512K RAM (total), done by replacing the CPC6128's RAM chips, and its PAL banking chip, the project was released 1987 in german magazine ''c't Magazin''.

MacDeath at 01:17, 17 December 2010

2010-12-17T01:17:56Z

← Older revision		Revision as of 01:17, 17 December 2010
Line 1:		Line 1:
			[[Category:DIY]]
	A project to upgrade a CPC6128 to 512K RAM (total), done by replacing the CPC6128's RAM chips, and its PAL banking chip, the project was released 1987 in german magazine ''c't Magazin''.		A project to upgrade a CPC6128 to 512K RAM (total), done by replacing the CPC6128's RAM chips, and its PAL banking chip, the project was released 1987 in german magazine ''c't Magazin''.

Nocash: /* PAL Source Code */

2010-05-08T15:52:50Z

PAL Source Code

← Older revision		Revision as of 15:52, 8 May 2010
Line 75:		Line 75:

	IF (GND) /IOWR=/IOWR ;dummy (do not output anything on this pin)		IF (GND) /IOWR=/IOWR ;dummy (do not output anything on this pin)

			'''Note:''' For VRAM access, bank bits 2,3,4 are forced to zero (by above formulas), bank bit 0,1 are coming from the CRTC, passed directly to IC109 (without going through the PAL), so, the RAM banking affects only the CPU's memory accesses, not the CRTC's video memory accesses.

	Some notes on the syntax:		Some notes on the syntax:

Nocash: /* Compatibility Problems */

2010-05-08T15:49:06Z

Compatibility Problems

← Older revision		Revision as of 15:49, 8 May 2010
Line 25:		Line 25:
	* RAMDIS is not supported, not a problem in most cases, but won't work with some special types of expansion hardware, like [[Multiface II]].		* RAMDIS is not supported, not a problem in most cases, but won't work with some special types of expansion hardware, like [[Multiface II]].
	* The expansion seems to have been designed independently of [[Standard Memory Expansions]] like the dk'tronics one. So, there is no (intended) compatibility. However, both c't and dk'tronics are designed around the CPC6128 banking mechanism, so they do work similar in some ways. Namely, both can map expansion banks to 4000h..7FFFh, but there are several differences:		* The expansion seems to have been designed independently of [[Standard Memory Expansions]] like the dk'tronics one. So, there is no (intended) compatibility. However, both c't and dk'tronics are designed around the CPC6128 banking mechanism, so they do work similar in some ways. Namely, both can map expansion banks to 4000h..7FFFh, but there are several differences:
	** For the mapping to 4000h..7FFFh, dk'tronics uses values CCh..CFh, D4h..C7h, DCh..DFh, ... FCh..FFh whilst c't uses values C8h..DFh. Some of these values do overlap, ~~providing~~ some (unintended) semi-compatibility, but there's still one big difference: along with the above values, dk'tronics maps bank 3 to C000h..FFFFh, whilst c't maps bank 7 to that region.		** For the mapping to 4000h..7FFFh, dk'tronics uses values CCh..CFh, D4h..C7h, DCh..DFh, ... FCh..FFh whilst c't uses values C8h..DFh. Some of these values do overlap, resulting in some (unintended) semi-compatibility, but there's still one big difference: along with the above values, dk'tronics maps bank 3 to C000h..FFFFh, whilst c't maps bank 7 to that region.

	== Memory Configurations ==		== Memory Configurations ==

Nocash: /* Compatibility Problems */

2010-05-08T15:48:20Z

Compatibility Problems

← Older revision		Revision as of 15:48, 8 May 2010
Line 24:		Line 24:

	* RAMDIS is not supported, not a problem in most cases, but won't work with some special types of expansion hardware, like [[Multiface II]].		* RAMDIS is not supported, not a problem in most cases, but won't work with some special types of expansion hardware, like [[Multiface II]].
	* The bank selection for CPU address 4000h..7FFFh does also affect bank bits0-1 for VRAM at 4000h..7FFFh; thus the CRTC may see bank 0-3 in that region (whilst, as far as known, on a normal CPC, it should always see bank 1 in that region).
	** '''Notice''' the included sample program '''does''' seem to map VRAM to 4000h, whilst mapping expansion banks to 4000h at the same time. Theoretically, this should result in display glitches - unknown if/how/why the sample works [?]
	* The expansion seems to have been designed independently of [[Standard Memory Expansions]] like the dk'tronics one. So, there is no (intended) compatibility. However, both c't and dk'tronics are designed around the CPC6128 banking mechanism, so they do work similar in some ways. Namely, both can map expansion banks to 4000h..7FFFh, but there are several differences:		* The expansion seems to have been designed independently of [[Standard Memory Expansions]] like the dk'tronics one. So, there is no (intended) compatibility. However, both c't and dk'tronics are designed around the CPC6128 banking mechanism, so they do work similar in some ways. Namely, both can map expansion banks to 4000h..7FFFh, but there are several differences:
	** For the mapping to 4000h..7FFFh, dk'tronics uses values CCh..CFh, D4h..C7h, DCh..DFh, ... FCh..FFh whilst c't uses values C8h..DFh. Some of these values do overlap, providing some (unintended) semi-compatibility, but there's still one big difference: along with the above values, dk'tronics maps bank 3 to C000h..FFFFh, whilst c't maps bank 7 to that region.		** For the mapping to 4000h..7FFFh, dk'tronics uses values CCh..CFh, D4h..C7h, DCh..DFh, ... FCh..FFh whilst c't uses values C8h..DFh. Some of these values do overlap, providing some (unintended) semi-compatibility, but there's still one big difference: along with the above values, dk'tronics maps bank 3 to C000h..FFFFh, whilst c't maps bank 7 to that region.

Nocash: /* Compatibility Problems */

2010-05-08T15:12:36Z

Compatibility Problems

← Older revision		Revision as of 15:12, 8 May 2010
Line 27:		Line 27:
	** '''Notice''' the included sample program '''does''' seem to map VRAM to 4000h, whilst mapping expansion banks to 4000h at the same time. Theoretically, this should result in display glitches - unknown if/how/why the sample works [?]		** '''Notice''' the included sample program '''does''' seem to map VRAM to 4000h, whilst mapping expansion banks to 4000h at the same time. Theoretically, this should result in display glitches - unknown if/how/why the sample works [?]
	* The expansion seems to have been designed independently of [[Standard Memory Expansions]] like the dk'tronics one. So, there is no (intended) compatibility. However, both c't and dk'tronics are designed around the CPC6128 banking mechanism, so they do work similar in some ways. Namely, both can map expansion banks to 4000h..7FFFh, but there are several differences:		* The expansion seems to have been designed independently of [[Standard Memory Expansions]] like the dk'tronics one. So, there is no (intended) compatibility. However, both c't and dk'tronics are designed around the CPC6128 banking mechanism, so they do work similar in some ways. Namely, both can map expansion banks to 4000h..7FFFh, but there are several differences:
	** For the mapping to 4000h..7FFFh, dk'tronics uses values CCh..CFh, D4h..C7h, DCh..DFh, ... FCh..FFh whilst c't uses values C8h..DFh. Some of these values do overlap, providing some (unintended) semi-compatibility, but there's still one big ~~differences~~: along with the above values, dk'tronics maps bank 3 to C000h..FFFFh, whilst c't maps bank 7 to that region.		** For the mapping to 4000h..7FFFh, dk'tronics uses values CCh..CFh, D4h..C7h, DCh..DFh, ... FCh..FFh whilst c't uses values C8h..DFh. Some of these values do overlap, providing some (unintended) semi-compatibility, but there's still one big difference: along with the above values, dk'tronics maps bank 3 to C000h..FFFFh, whilst c't maps bank 7 to that region.

	== Memory Configurations ==		== Memory Configurations ==

Nocash at 15:03, 8 May 2010

2010-05-08T15:03:07Z

← Older revision		Revision as of 15:03, 8 May 2010
Line 26:		Line 26:
	* The bank selection for CPU address 4000h..7FFFh does also affect bank bits0-1 for VRAM at 4000h..7FFFh; thus the CRTC may see bank 0-3 in that region (whilst, as far as known, on a normal CPC, it should always see bank 1 in that region).		* The bank selection for CPU address 4000h..7FFFh does also affect bank bits0-1 for VRAM at 4000h..7FFFh; thus the CRTC may see bank 0-3 in that region (whilst, as far as known, on a normal CPC, it should always see bank 1 in that region).
	** '''Notice''' the included sample program '''does''' seem to map VRAM to 4000h, whilst mapping expansion banks to 4000h at the same time. Theoretically, this should result in display glitches - unknown if/how/why the sample works [?]		** '''Notice''' the included sample program '''does''' seem to map VRAM to 4000h, whilst mapping expansion banks to 4000h at the same time. Theoretically, this should result in display glitches - unknown if/how/why the sample works [?]
			* The expansion seems to have been designed independently of [[Standard Memory Expansions]] like the dk'tronics one. So, there is no (intended) compatibility. However, both c't and dk'tronics are designed around the CPC6128 banking mechanism, so they do work similar in some ways. Namely, both can map expansion banks to 4000h..7FFFh, but there are several differences:
			** For the mapping to 4000h..7FFFh, dk'tronics uses values CCh..CFh, D4h..C7h, DCh..DFh, ... FCh..FFh whilst c't uses values C8h..DFh. Some of these values do overlap, providing some (unintended) semi-compatibility, but there's still one big differences: along with the above values, dk'tronics maps bank 3 to C000h..FFFFh, whilst c't maps bank 7 to that region.

	== Memory Configurations ==		== Memory Configurations ==
Line 81:		Line 83:
	* The "" and "+" operators are meaning " = AND", "+ = OR". The idea behind that confusing syntax was to make it "easier" to learn for people who are trained only in basic maths (the formulas do also work when treating *=multiply, and +=plus. For example: 1+0+1+1 = 3 = nonzero = true).		* The "" and "+" operators are meaning " = AND", "+ = OR". The idea behind that confusing syntax was to make it "easier" to learn for people who are trained only in basic maths (the formulas do also work when treating *=multiply, and +=plus. For example: 1+0+1+1 = 3 = nonzero = true).
	* There must be some priority ordering in the formulas: Either * before +, or operations inside of a line before merging the results of the separate lines (in above examples, both ordering methods do work).		* There must be some priority ordering in the formulas: Either * before +, or operations inside of a line before merging the results of the separate lines (in above examples, both ordering methods do work).

	~~== Newer Info ==~~

	~~Having a short look at the article, it seems to be all different as than expected:~~

	* There is no dk'tronics compatibility intended - however, c't and dk'tronics are based on the CPC6128 banking mechanism, so they work similar, and to some level there is some (unintended) compatibility. Namely, ONE HALF of the memory can be accessed in dk'tronics style fashion.

	* There seems to be no hardware based "Video RAM" support at all. However, there's some unspectacular software based example included that copies expansion RAM to VRAM via LDIR opcode.

	== Scanned Article / Schematics ==		== Scanned Article / Schematics ==

Nocash at 14:51, 8 May 2010

2010-05-08T14:51:06Z

← Older revision		Revision as of 14:51, 8 May 2010
Line 1:		Line 1:
	A project to upgrade a CPC6128 to 512K RAM (total), done by replacing the CPC6128's RAM chips, and its PAL banking chip, the project was released 1987 in german magazine ''c't Magazin''.		A project to upgrade a CPC6128 to 512K RAM (total), done by replacing the CPC6128's RAM chips, and its PAL banking chip, the project was released 1987 in german magazine ''c't Magazin''.

	~~== Technical ==~~

	The memory is accessed via Port 7Fxxh, as on [[Standard Memory Expansions]]. Since the internal RAM is removed, its total capacity is only 512K (unlike standard 512K expansions which provide 64K internal plus 512K external memory, ie. 576K total). Altogether, the c't expansion works like a 448K dk'tronics expansion (leaving the banks selected via OUT [7Fxxh],FCh..FFh unused).

	One half (256K) of the total (512K) expansion memory can be accessed as Video RAM (with normal expansions, only 64 KB are accessible as VRAM). This is making the expansion slightly incompatible with the dk'tronics standard. However, usually expansion memory is mapped to 4000h-7FFFh, whilst VRAM is usually mapped to C000h-FFFFh. So, most existing software may work with it, without accidently displaying garbage on the screen.

	== The Circuit ==		== The Circuit ==
Line 31:		Line 25:
	* RAMDIS is not supported, not a problem in most cases, but won't work with some special types of expansion hardware, like [[Multiface II]].		* RAMDIS is not supported, not a problem in most cases, but won't work with some special types of expansion hardware, like [[Multiface II]].
	* The bank selection for CPU address 4000h..7FFFh does also affect bank bits0-1 for VRAM at 4000h..7FFFh; thus the CRTC may see bank 0-3 in that region (whilst, as far as known, on a normal CPC, it should always see bank 1 in that region).		* The bank selection for CPU address 4000h..7FFFh does also affect bank bits0-1 for VRAM at 4000h..7FFFh; thus the CRTC may see bank 0-3 in that region (whilst, as far as known, on a normal CPC, it should always see bank 1 in that region).
			** '''Notice''' the included sample program '''does''' seem to map VRAM to 4000h, whilst mapping expansion banks to 4000h at the same time. Theoretically, this should result in display glitches - unknown if/how/why the sample works [?]

	== ~~Missing Info~~ ==		== Memory Configurations ==

	* Unknown which banks are usable as VRAM
	** The first four 16K bank are (probably) usuable as VRAM (as on all 64K CPC models)
	** The next four 16K bank are (hopefully) not usuable as VRAM (for CP/M+ compatibility, which uses them as Work RAM)
	** For further banks it's totally unknown if they are used as VRAM or not
	* Unknown if it's fully dk'tronics compatible, or more like incompletely implemented Inicron variant
	* Unknown what happens on accessing the unused region via OUT [7Fxxh],FCh..FFh

	~~== Memory Configurations ==~~		The memory is controlled by OUT [7Fxxh],C0h..DFh instructions. Values C0h..C7h are working same as on normal CPC6128s. Values C8h..DFh do access the additional RAM banks (C8h..D3h when using the cut-down 320K upgrade variant).

	OUT [7Fxxh],C0h+... 0 1 2 3 4 5 6 7 8..31		OUT [7Fxxh],C0h+... 0 1 2 3 4 5 6 7 8..31
Line 51:		Line 39:

	== PAL Source Code ==		== PAL Source Code ==

			Below is a typed-up and commented copy of the PALASM source code from the original article.

	D7D6 D0 D3 D4 D1 D2 NCAS A15 A14 GND ;pin 1..10		D7D6 D0 D3 D4 D1 D2 NCAS A15 A14 GND ;pin 1..10
Line 85:		Line 75:

	IF (GND) /IOWR=/IOWR ;dummy (do not output anything on this pin)		IF (GND) /IOWR=/IOWR ;dummy (do not output anything on this pin)

			Some notes on the syntax:
			* The first two lines assign the pin-outs. Observe that leading "/" slashes are omitted here. For example, "/CPU" (in schematic) becomes "CPU" (in source code). Accordingly "/CPU" (in source code) would be double-negated "//CPU" aka "CPU" (in schematic).
			* The "IF (condition) signal=" part means that "signal" becomes an output when condition is true. In the above source code, condition is always true (VCC), or, for the last 2 lines, always false (GND).
			* The "" and "+" operators are meaning " = AND", "+ = OR". The idea behind that confusing syntax was to make it "easier" to learn for people who are trained only in basic maths (the formulas do also work when treating *=multiply, and +=plus. For example: 1+0+1+1 = 3 = nonzero = true).
			* There must be some priority ordering in the formulas: Either * before +, or operations inside of a line before merging the results of the separate lines (in above examples, both ordering methods do work).

	== Newer Info ==		== Newer Info ==

Nocash at 14:30, 8 May 2010

2010-05-08T14:30:45Z

← Older revision		Revision as of 14:30, 8 May 2010
Line 1:		Line 1:
	A project to upgrade a CPC6128 to 512K RAM (total), done by replacing the CPC6128's RAM chips, and its PAL banking chip, the project was released 1987 in german IT magazine '''c't'''.		A project to upgrade a CPC6128 to 512K RAM (total), done by replacing the CPC6128's RAM chips, and its PAL banking chip, the project was released 1987 in german magazine ''c't Magazin''.

	== Technical ==		== Technical ==