6 MHz CPC - Revision history

Eto: /* Disadvantages */

2024-04-22T19:48:51Z

‎Disadvantages

Eto: /* Advantages */

2024-04-22T19:47:40Z

‎Advantages

Eto: /* Disadvantages */

2024-04-22T19:43:23Z

‎Disadvantages

Eto: /* Disadvantages */

2024-04-22T19:27:20Z

‎Disadvantages

Scruss: /* Measurement of speed */ - speed test had syntax error - should be gosub, not goto

2020-11-14T20:14:00Z

‎Measurement of speed: - speed test had syntax error - should be gosub, not goto

Polluks at 18:04, 17 February 2016

2016-02-17T18:04:05Z

Polluks at 18:00, 17 February 2016

2016-02-17T18:00:15Z

1024MAK at 12:08, 17 February 2016

2016-02-17T12:08:35Z

TFM: /* Measurement of speed */

2013-03-08T15:21:01Z

‎Measurement of speed

TFM: /* Advantages */

2013-03-06T17:03:21Z

‎Advantages

@@ Line 23: / Line 23: @@
 * RAM should to be at least 160ns fast. Many CPCs only have 200ns RAM built-in. Replacing RAM requires to desolder the old RAM ICs.
 * Z80 might need being replaced by a 6MHz capable version. Pay attention to get a NMOS version of the Z80 as the CMOS version has different behavior for some undocumented but (rarely) used opcodes
 * The horizontal timing of the CRTC is affected. In order to get a stable image, you need to program register 0 at 95 (96 characters line) and Register 2 at 61 (centering for 40 characters default)
-* Pixels pitch is 66.7% of their original pitch.Theses pictures show this fact (320×200 mode 1 pixels with black border)
+* Pixels are no longer square. Their pitch is 66.7% of their original pitch. Theses pictures show this fact (320×200 mode 1 pixels with black border)
 <gallery>
 Image:12062011055.JPG|Original CPC @16Mhz
 Image:12062011054.JPG|Overclocked CPC @24Mhz
 </gallery>
 == Software ==

@@ Line 7: / Line 7: @@
 == Advantages ==
-* Z80 runs with 6 MHz
+* The whole computer runs 50% faster. Z80, Bus, RAM, CRTC run with 6 MHz, GateArray with 24MHz, Soundchip with 1.5MHz
-* Bus runs with 6 MHz
+* FDC is 50% faster, Disc formats with 50% more sectors can be used after adjusting the DOS paramaters
-* FDC is 50% faster
+* Sound that is programmed specifically for a 6MHz CPC can sound better than on a 4MHz CPC
-* Disc formats with 50% more sectors can be used
+* Games can run more fluid
-* Sound can be better, since the PSG runs more quickly
 * Games run more fluid
 * Graphics are better, pixel are about 1/3 smaller in X
 * By adjusting the CRTC an higher frame rate can be used (75 Hz)

@@ Line 17: / Line 17: @@
 == Disadvantages ==
-* FDC can't read old disc formats any longer. It is not possible to exchange discs with a 4MHz CPC.
 * Not every hardware expansion is able to work with the 6 MHz bus speed. So also other options to load data and programs on a 6MHz CPC can become difficult.
 * Not all GateArrays will work with a 24MHz crystal
-* RAM should to be at least 160ns fast. Many CPCs only have 200ns RAM built-in
+* RAM should to be at least 160ns fast. Many CPCs only have 200ns RAM built-in. Replacing RAM requires to desolder the old RAM ICs.
 * The horizontal timing of the CRTC is affected. In order to get a stable image, you need to program register 0 at 95 (96 characters line) and Register 2 at 61 (centering for 40 characters default)
 * Pixels pitch is 66.7% of their original pitch.Theses pictures show this fact (320×200 mode 1 pixels with black border)
@@ Line 27: / Line 31: @@
 Image:12062011054.JPG|Overclocked CPC @24Mhz
 </gallery>
-* Sound must be reprogrammed
+* Sound must be reprogrammed / patched. No patches are publicly available.
 == Software ==

@@ Line 17: / Line 17: @@
 == Disadvantages ==
-* FDC can't read old disc formats any longer
+* FDC can't read old disc formats any longer. It is not possible to exchange discs with a 4MHz CPC.
 * The horizontal timing of the CRTC is affected. In order to get a stable image, you need to program register 0 at 95 (96 characters line) and Register 2 at 61 (centering for 40 characters default)
 * Pixels pitch is 66.7% of their original pitch.Theses pictures show this fact (320×200 mode 1 pixels with black border)
@@ Line 24: / Line 27: @@
 Image:12062011054.JPG|Overclocked CPC @24Mhz
 </gallery>
 * Sound must be reprogrammed

@@ Line 46: / Line 46: @@
 i = 0
-after 500 goto 100
+after 500 gosub 100
 cls
 i = i +1

@@ Line 1: / Line 1: @@
-The '''6 MHz''' CPC is a [[DIY]] hardware modification which allows to run the [[CPC6128]] with a CPU speed of 6 MHz instead of the usual 4 MHz.
+The 6 MHz CPC is a [[DIY]] hardware modification which allows to run the [[CPC6128]] with a CPU speed of 6 MHz instead of the usual 4 MHz.
 == Technic ==
 The 16 MHz crystal of the CPC is replaced by a 24 MHz crystal. Both crystals should kept on the main board, but a switch (a DPDT type, switching both lines to both crystals is recommended) selects between them. Keep the wiring tidy and very short. You have to select the CPU and bus speed before you switch on the CPC. Switching the speed while the system is switched on is not advised.
-If you attempt this modification, it is at your own risk. None of the authors of this article can or will be held responsible for any damage to your CPC as a result of your DIY work.
+'''If you attempt this modification, it is at your own risk. None of the authors of this article can or will be held responsible for any damage to your CPC as a result of your DIY work.'''
 == Advantages ==

@@ Line 1: / Line 1: @@
-The 6 MHz CPC is a DIY hardware modification which allows to run the [[CPC6128]] with a CPU speed of 6 MHz instead of the usual 4 MHz.
+The '''6 MHz''' CPC is a [[DIY]] hardware modification which allows to run the [[CPC6128]] with a CPU speed of 6 MHz instead of the usual 4 MHz.
@@ Line 29: / Line 29: @@
 == Software ==
 * A lot of games run well with 6 MHz. For example: Nebulus, StarFox, Starstrike and others.
-* There is a 6 MHz version of FutureOS
+* There is a 6 MHz version of [[FutureOS]]
 == Testing ==

@@ Line 3: / Line 3: @@
 == Technic ==
-The 16 MHz crystal of the CPC is replaced by a 24 MHz crystal. Both crystals should kept on the main board, but a switch (2 lines at least, better 3) selects between them. You have to select the CPU and bus speed before you switch on the CPC. Switching the speed while the system is switched on is not advised.
+The 16 MHz crystal of the CPC is replaced by a 24 MHz crystal. Both crystals should kept on the main board, but a switch (a DPDT type, switching both lines to both crystals is recommended) selects between them. Keep the wiring tidy and very short. You have to select the CPU and bus speed before you switch on the CPC. Switching the speed while the system is switched on is not advised.
-None of the authors of this article is responsible for danger on your CPC, in case you try to use this DIY.
+If you attempt this modification, it is at your own risk. None of the authors of this article can or will be held responsible for any damage to your CPC as a result of your DIY work.
 == Advantages ==
@@ Line 30: / Line 30: @@
 * A lot of games run well with 6 MHz. For example: Nebulus, StarFox, Starstrike and others.
 * There is a 6 MHz version of FutureOS
 == Measurement of speed ==
-* Some CPCs (manufactured with fast DRAMs) show a increase of speed by 50% (verified with at least one CPC6128 produced 1987).
+* If your machine starts up okay, you can test the modification with this simple program :
-−
-* In case of the older DRAM type the speed improvement is only 16.7%.This has been tested with this simple program :
 i = 0
@@ Line 46: / Line 53: @@
 end
-Score is 258 on normal CPC versus 301 on 24 MHz CPC.
+Score is 258 on normal CPC versus 301 when using a CPC fitted with a 24 MHz crystal.
-(Theses results can be subject to discussion as we are not sure interrupts timing is not affected)
+(Theses results can be subject to discussion as we are not sure how interrupt timing is affected).
 [[Category:DIY]][[Category:Hardware]]

@@ Line 33: / Line 33: @@
 == Measurement of speed ==
-* This speed improvement is 16.66667%.This has been tested with this simple program :
 i = 0