The SuperCPU FAQ

The SuperCPU FAQ - find answers to your questions. If you do not find your question here, if you want to add something to a certain answer or if you just want to give a comment, e-mail me!
Attention: The SuperCPU Troubleshooting-Section is STILL TO COME, so don't be suprised that it's not there.

Here we go:

Q: Is it possible to turn off the SuperCPU and turn back to a normal C64?
Q: With a SuperCPU - is the C64 still the C64?
Q: The SuperCPU has its own processor; what is it, some kind of Motorola or even Intel chip?
Q: Tuning up the C64 with a SuperCPU - wouldn't this be just the start of a tune-up-insanity like on the PC?
Q: Isn't the SuperCPU awfully expensive?
Q: Will my drive load 20 times faster, too?
Q: Will Turrican and such games run 20 times faster? Will all demos run 20 times faster?
Q: Will music play 20 times faster?
Q: How do you put memory into the SuperCPU? I heard it is possible to put up to 16 MB into it?
Q: I have a C128. Do I need the SuperCPU128 then?
Q: I heard of different versions of the SuperCPU, V1 and V2. What is the difference?
Q: Will programs written and timed to work on SuperCPU V1 be 100% compatible with V2 and vice versa?
Q: Is it possible to upgrade a V1 to a V2?
Q: Is RAM added to the SuperCPU just used as RAM disk?
Q: Which other expansions are compatible with the SuperCPU?
Q: The SuperCPU requires a lot of electric power, how can I get it? My old power supply doesn't provide that much.
Q: Sometimes when the computer tries to load inside a demo or game, the SuperCPU crashes. What can be done?
Q: On the C128, the VIC can't stand 2 MHz. How can it stand 20 MHz now with the SuperCPU?
Q: The SuperCPU uses its own RAM. The VIC cannot access memory outside the C64 - so how it can display graphics with a SuperCPU plugged in?
Q: When powering up my SuperCPU-equipped C64, I sometimes get the message "SCPU Initialization Error #6". The SuperCPU user guide does not inform me about its meaning. What's the problem?
Q: Some games I've played do not allow me to reset my SuperCPU-equipped C64. There's always the game's introduction screen appearing again. Even switching off my computer doesn't solve the problem. What can I do?

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Q: Is it possible to turn off the SuperCPU and turn back to a normal C64?
A: Of course you can turn off your SuperCPU. Unlike turbo boards on the Amiga, the SuperCPU can be completely disabled using a switch - then you have normal C64 mode, as if there was no SuperCPU connected. You can also toggle the SuperCPU between 1 MHz and 20 MHz while running programs, without crashes or reloading.
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Q: With a SuperCPU - is the C64 still the C64?
A: Yes, definitely. The original C64 feeling stays, the VIC graphics and the SID musics stays - and I doubt that anybody liked the C64 because of its slow processing speed. With the SuperCPU, the C64 does NOT become a totally new, totally different computer - it stays as your C64!
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Q: The SuperCPU has its own processor; what is it, some kind of Motorola or even Intel chip?
A: No! The SuperCPU features the 65816 processor, an enhanced version of the 6502/6510! It can understand all C64 machine language instructions, so it is able to run existing C64 software. But it also features new instructions (opcodes) that provide a lot of power. Programmed in the right way, the SuperCPU can be up to 40 times faster than a normal C64. Programming the SuperCPU is fascinating for all who are familiar with the 6510, because the 65816 has the same concept, with more possibilities (like addressing memory above $FFFF, have accu, X and Y registers with 8 or 16 bits, fast commands to transfer whole blocks of memory at once and so on).
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Q: Tuning up the C64 with a SuperCPU - wouldn't this be just the start of a tune-up-insanity like on the PC?
A: No. First, PCs have to be tuned up because they are bad like they are, and after the tuning they aren't quite so bad. The C64 is great like it is, and with the SuperCPU, it becomes even better. Second, there probably will be no further development; no graphics board, no faster processor and so on. With a SuperCPU, you upgrade your C64 once and for all - you don't have to buy a new device about 6 months later!
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Q: Isn't the SuperCPU awfully expensive?
A: No. First: on the Amiga, you pay more than 1000 DM for a 5-6 times performance increase (PPC-board). On the PC, you pay more than 1000 DM if you throw away your old Pentium and buy a Pentium III - for a 3-4 times performance increase. On the C64, you pay just 399 DM for a TWENTY times performance increase! Second: the number of produced SuperCPUs is much smaller than the number of Amiga turbo boards or even new PCs. The fixed costs are spread over fewer SuperCPUs. Considering these two facts, the SuperCPU really cannot be called expensive.
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Q: Will my drive load 20 times faster, too?
A: No, the speed of the drive depends more on other things than on processor speed. But the SuperCPU comes with built-in JiffyDOS, so if your drives are JiffyDOS-equipped (FD and HD drives from CMD are from the factory, Commodore drives are not) it will load fast. If not, you can get a JiffyDOS chip for your drive (available for all types, including 1581) to have fast loading. If you also have a JiffyDOS chip for the C64/128, the drives will load faster even without the SuperCPU. There is one special case up: the RAMLink. Data transfer between this special RAM-diskdrive is sped up with the SuperCPU.
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Q: Will Turrican and such games run 20 times faster? Will all demos run 20 times faster?
A: No. Turrican bases on VIC interrupt programming. The VIC is still the same and so Turrican will run in the same speed. However the routines now use 1/20th of the available rastertime - meaning much more can now be done in one frame. The same applies for many demos - it is common even for vector parts not to be sped up because there is a routine which waits for the raster-ray (a register in the VIC tells where it is) and calculates one movement each frame. In comparison, when the routine is run as a "main program" it will not wait with its calculations until the VIC has reached a certain line, so it will be sped up a lot. Also, the cursor will not blink faster, because it is triggered by a CIA timer interrupt.
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Q: Will music play 20 times faster?
A: No. Music is played synchronized with the raster ray register in the VIC. It stays the same with the SuperCPU; music will play in the same speed, but use much less rastertime. In rare cases music might sound a bit different because some instruments rely on times between changes of certain SID registers. Some digitized music or other music that is not played with the help of IRQ or NMI may play faster.
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Q: How do you put memory into the SuperCPU? I heard it is possible to put up to 16 MB into it?
A: First you need the RamCard (SuperCard); it is installed onto the SuperCPU main board. On this card there is a PS/2-SIMM socket in which you can place a 1 MB, 4 MB, 8 MB or 16 MB PS/2-SIMM. Only FastPage-type is supported; EDO doesn't work. If FastPage is not available at your local store, you can still get it via mail order or out of older PCs. It doesn't matter if the access time is 70ns or 60ns, the controller on the SuperRAM-card takes care of that - a read or write always lasts the same time, regardless of the kind of RAM.
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Q: I have a C128. Do I need the SuperCPU128 then?
A: Not if you only use the C128 in C64 mode (as most people do), if this is the case then you can use the SuperCPU64. You only need the SuperCPU128 if you want to speed up the C128 mode.
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Q: I heard of different versions of the SuperCPU, V1 and V2. What is the difference?
A: The V2 often is much faster because it has a special optimization mode, which excludes certain areas of memory which are used often (stack and zero page). This can be turned off for the rare case that a SuperCPU-specific program requires exactly the speed of an V1.
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Q: Will programs written and timed to work on SuperCPU V1 be 100% compatible with V2 and vice versa?
A: Programs made for the V1 will work 100% on V2 - in rare cases where problems occur the V2 can be switched to a mode where it behaves like a V1 ("no optimization"). A program which uses the special optimization modes of the V2 may run slower on V1 or behave strange, but usually there are no problems.
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Q: Is it possible to upgrade a V1 to a V2?
A: No, because the V2 uses a PLD with higher chip density which does not fit into the V1.
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Q: Is RAM added to the SuperCPU just used as RAM disk?
A: No. Unlike RAMLink or REU devices, the RAM on the RamCard can also be used for programs. The processor can directly access it and therefore with 1 MB RAM, you have a C64 with 1 MB RAM, not with 64K and some RAM disk. Specially written programs can benefit from this RAM and much more powerful software can be written. GEOS can use it as a RAM disk.
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Q: Which other expansions are compatible with the SuperCPU?
A: All CMD expansions, including RAMLink, work with the SuperCPU. Swiftlink/Turbo232 also works. Commodore REUs work, too, all with the SuperCPU turned on. Nordic Power, Action Replay and Final Cartridge III however do not work, the SuperCPU has to be turned off or removed to get these cartridges to work.
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Q: The SuperCPU requires a lot of electric power, how can I get it? My old power supply doesn't provide that much.
A: Try to get a REU power supply (was included in the original Commodore 1764 REU package), it provides enough power. Or take a C128 power supply and replace the connector with a C64 power connector. A final possibility is to build an adaptor with which you can connect two C64 power supplies at the same time (see the SuperCPU troubleshooting section).
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Q: Sometimes when the computer tries to load inside a demo or game, the SuperCPU crashes. What can be done?
A: Switch to 1 MHz while loading. Some games and demos use IRQ - or fast loaders which depend on the speed of 1 MHz. Normally, the SuperCPU automatically switches to 1 MHz while loading, but some routines bypass the kernal so the SuperCPU can't know. After loading, you can switch back to 20 MHz.
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Q: On the C128, the VIC can't stand 2 MHz. How can it stand 20 MHz now with the SuperCPU?
A: Because CMD is ingenious! ;-) - Because the C64 internal still works with 1 MHz, including VIC and SID. When writing to the registers of C64 chips, the write cycle is done in 1 MHz. This slows down the SuperCPU a bit, but not noticeably.
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Q: The SuperCPU uses its own RAM. The VIC cannot access memory outside the C64 - so how it can display graphics with a SuperCPU plugged in?
A: Every time a byte is stored to memory, this is done twice: into the RAM of the SuperCPU AND into the RAM of the C64. This is done with all writes, because the SuperCPU can't tell whether it is graphical data or not. Because the C64 RAM still works with 1 MHz, a write is cached and done within a 1 MHz cycle. If another write occurs within this time, the SuperCPU has to wait. This can cause slowdowns, but only while writing - reading is performed directly from the SuperCPU RAM with 20 MHz.
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Q: When powering up my SuperCPU-equipped C64, I sometimes get the message "SCPU Initialization Error #6". The SuperCPU user guide does not inform me about its meaning. What's the problem?
A: The problem is too weak a power supply. When the SuperCPU doesn't get enough power, it behaves unexpectedly and in a strange way. Since in this case the SuperCPU itself cannot determine what's wrong with the system, it provides the message Error #6 instead. Refer to the SuperCPU troubleshooting section to find a right solution for power problems.
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Q: Some games I've played do not allow me to reset my SuperCPU-equipped C64. There's always the game's introduction screen appearing again. Even switching off my computer doesn't solve the problem. What can I do?
A: Wait a bit longer after turning off the computer. CMD have installed SRAM-chips into their SuperCPU that consume only a fraction of power that the old Commodore DRAMs do. That's why they can maintain a reset-protected program for a much longer time. You may occasionally need to disconnect your SCPU for a few seconds. This should remove the program from the RAM to ensure a correctly resetting C64 again.
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