General Specifications

The Western Design Center's 20 MHz W65C816S. The fastest version of this chip ever produced, it provides 8-bit 6502 emulation as well as an enhanced 16-bit Native operating mode. The W65C816S is capable of directly addressing up to 16 MB of memory, and and enhanced instruction set which allows more powerful programming using fewer instructions. Despite the additional instructions, this processor remains fully backward-compatible with all legal 65xx family processor instructions.
An Altera Complex Programmable Logic Device provides the custom logic required to interface the new processor to your computer. CMD spent several hundred man-hours creating the custom programming for this chip that is vital in making the SuperCPU mimic the C-64's own internal logic.
128K of Fast Static RAM gives the SuperCPU the ability to access program instructions and data at the full speed capability of the processor. Half of this fast RAM is used to replace the 64K of RAM that you normally have for programming in the Commodore 64. The other half is used as a form of Operating System ROM (OSROM). By reading the Operating System directly into RAM, the SuperCPU can deliver full speed when accessing routines that are normally ROM-based. If a ROM were used instead, memory 'wait-states' would be required which would decrease the efficiency of the accelerator.
128K is supplied in the present SuperCPU 64. This ROM contains the Operating System overlays, which are downloaded into the OSRAM. The SuperCPU can accept up to 512K of ROM, however, and CMD is working on additional feaures that will use this additional capacity.
Pass-Thru Port
A standard 44-pin Commodore Expansion/Cartridge Port is located at the rear of the SuperCPU. This port lets you plug in and use many of the cartridges and I/O devices available for Commodore computers.
Switches and Indicators
Three toggle switches protrude from the top of the unit and provide a master Unit Enable/Disable, JiffyDOS Enable/Disable, and Speed Select (Normal/Turbo). Whenever the unit is operating in 20 MHz mode, the Turbo Indicator LED (top edge left of center) lights to indicate this A push-button Reset switch is also provided (top left edge).
Power Requirements
The SuperCPU (without the RAM expansion option) draws approximately .4 amps from your computer's power supply. Commodore 128 (and 128-D) computers provide ample power for this device. However, if you use your SuperCPU on a Commodore 64 or Commodore 64c, we highly recommend a heavy-duty power supply. CMD offers such a supply (5 VDC @ 3 Amps and 9 VDC @ 1 Amp), Order Code: POWER64HD. WARNING: The current draw of the SuperCPU will very likely shorten the life expectancy of stock C-64 power supplies.

SuperCPU General Information

The SuperCPU is an accelerator module that plugs into the C64/128 Cartridge port. At its heart is the W65C816S microprocessor running at 20 MHz, along with 128K Bytes of high-speed Static RAM (the same type of high-speed cache memory found in 486/Pentium systems), 128K Bytes of ROM, and a Complex Programmable Logic Device IC (CPLD).

The SuperCPU is contained within an enclosure approx. 6-1/4" wide x 4" tall x 2" deep. The enclosure has an opening for the Cartridge-Port Pass-Thru connector at the rear, in line with the host computer's own Cartridge Port. The main circuit board in the SuperCPU mounts vertically, so as to keep the depth of the unit to a minimum. This helps to prevent devices plugged into the pass-through port on the CPU from extending too far back from the computer. Three easy-to-use toggle switches line the upper front edge of the unit: A Unit Enable/Disable switch; a JiffyDOS Enable/Disable switch; and a speed selection switch. A push-button Reset switch and Turbo mode indicator LED are also provided.

Installing the SuperCPU 64 is simple: just plug it into the Cartridge port. No wiring or jumpers need to be installed inside of the computer, and there's no manual 'fine-tuning' adjustments to be made. (Note: The SuperCPU 128 will require mounting an internal 'daughter-board' in your computer).

Operating the SuperCPU requires no special knowledge. The user can perform all computer tasks in exactly the same manner as with a stock system, while gaining the benefits of accelerated speed. The toggle switches on the unit are clearly labeled, easily accessible, and can be used without having to refer to a manual in order to determine their function.

The SuperCPU 64 operates with C-64 and C-64c computers as well as the C-128/128-D in 64 mode. The W65C816S processor supports all legal 65xx-family processor opcodes, providing a very high level of compatibility with existing software -- including GEOS. The C-64 memory map is emulated exactly, and proprietary write-thru logic ensures full compatibility with all VIC graphic modes and memory mapping.

To help achieve a high level of performance, all operating system routines are downloaded into the high-speed Static RAM upon power-up, eliminating the bottleneck caused by ROM-based operating system code (on PC's, this technique is called ROM-BIOS shadowing). 64K of high-speed SRAM remains free for programs -- just like in a standard C-64. In addition, buffered write-thru circuitry (similar to PC cache-controllers) helps the SuperCPU avoid slow downs when writing data back into the C-64's RAM.

Additional Features

JiffyDOS: The JiffyDOS Kernal ROM for the computer is built into the SuperCPU, providing DOS-Wedge commands and enabling high-speed serial transfer rates to and from JiffyDOS-equipped disk drives. A JiffyDOS disable switch is provided so that the SuperCPU can load programs which are not compatible with JiffyDOS. This switch can be used to enable or disable JiffyDOS while the CPU is running, and does not affect the operating speed.

Pass-Thru Port: The SuperCPU includes a Cartridge Port Pass-Thru connector which enables the full use of most plug-in hardware devices such as Commodore REU's, RAMLink, Swiftlink, SID Cartridge, and GEORAM. These devices will work with the CPU running at 20 MHz and will not require a slowdown to 1MHz. Most ROM cartridges (generally games) will either force the SuperCPU to 1 MHz mode, or require that you manually switch off Turbo.

REU Compatibility: The CPLD chip in the SuperCPU includes special DMA transfer logic to provide 100% compatibilty with all types of data transfers to and from Commodore REU's. The SuperCPU does not have to slow down to 1 MHz in order to perform DMA transfers to and/or from the REU.

RAMLink Compatibility: The SuperCPU is 100% compatible with RAMLink, and contains its own version of RLDOS, which will run from the SuperCPU's high-speed static RAM. The faster RLDOS, along with the efficiency of new 65C816 opcodes will enable the SuperCPU to transfer data to and from all of the memory on RAMLink's RAMCard at speeds which rival the DMA transfer rate of Commodore REU's. Transfer rates to and from CMD HD-Series hard drives connected to RAMLink's parallel port will also be significantly faster.

GEOS: Special features include the necessary Configure and driver software to optimize GEOS for operation with the SuperCPU. In addition, an intelligent write-thru hardware circuit designed especially for GEOS effectively eliminates a major performance bottleneck associated with earlier accelerator designs such as the Turbomaster and Flash-8. This design feature, coupled with the 20 MHz clock speed of the WDC65C816S boosts the performance of GEOS far beyond anything currently possible or imaginable.

Expansion Capability: The SuperCPU is equipped with an internal connector which is to be used for the C-128 option board and for an optional RAM Expansion card (available in late '96). Each of these cards will have on-board SIMM sockets and can contain from 1 to 16 Megabytes of Dynamic RAM (DRAM). The RAM on this card can be used as additional programming space for advanced applications software.

Speed Selection: The speed selection switch provides on-the-fly switching between 1 MHz mode and 20 MHz (Turbo) mode. The 1 MHz option can be used for compatibility with programs (such as some games and cartridges) that may operate too quickly in the Turbo mode. Speed can also be altered via software using a simple POKE command, provided the unit is in Turbo mode. (Note: The SuperCPU performs disk access functions properly in any speed mode.)

Copyright © 1996 by Creative Micro Designs, Inc.