David-65

[Diddl]

I can proudly pronounce a new PCB board: David-65

Nils from "For8Bits" is developing a new hardware for 6502 systems/computers.


It is very similar to Final Expansion for VIC-20, but it is much more universal useable. David-65 works on every 6502 board: PET, CBM, VIC-20, any Commodore Floppy ...


Simply do following to install David-65:

* remove 6502 CPU (hope it has a socket)
* insert David-65 into CPU socket
* insert CPU into David-65 board


David-65 offers nearly same features than a FE2:

• CPLD for programmable memory configuration
• additionally 512 Kb SRAM
• additionally 512 Kb Flash (programmable)
• a RS-232, very slow - only for debugging (software driven like in a C-64)
• a LED for diagnostic purposes

What are the benefits for using a David-65:

• extension of a PET / CBM / VIC
  
  Any PET or CBM with 8KB or 16KB will have 32KB also
  
  If RAM or ROM (or both) is damaged David-65 will replace it without soldering
  
  You can choose between any BASIC, any Kernal and any Software extension (ExBasic, Assembler, ...). You can switch between different editor ROM and different languages. And of course any RAM configuration, also for address ranges where is normally ROM (kernel, Basic, ...).
  
  New Software can use whole 1MB of the David-65 memory
• Diagnostic
  
  David-65 can start with own Flash and own RAM, so nearly no "external" hardware is nessecary. Only power and clock for the CPU is nessecary to run diagnostic.
  
  A badly hard damaged 6502 system could be analysed from CPU's sight. Even if Kernel or Zeropage is damaged, David-65 will find it out.
• Ultimative Speeder for a 1541 drive (200 times!)
  
  My personal favourite goal is the ultimate speeder for a floppy drive (1541, 1571). David-65 can hold two full D64 Images or one D71 image. Installed in a 1541 floppy David-65 can read whole disk into memory and so access data in RAM disk like speed. Write access goes into RAM and will be written in idle time (lazy write back).
• David-65 can act as a standalone 6502 board if a 5V power and a clock is available ...

Many other things are possible with David-65, cause CPLD design makes it possible to adapt it to any 6502 system.

[Richard James]

Is it an ICE? In Circuit Emulator. As in you can load the code and step the machine through each instruction?

[rhurst]

That's a hefty list of features ...

[Diddl]

Is it an ICE? In Circuit Emulator. As in you can load the code and step the machine through each instruction?

No, not an ICE.


It is simply a intermediate socket for your 6502 CPU.

David-65 can work transparent, like it would not exist, your system works like bevore.

David-65 can overlay some memory regions with own memory (David-65 memory).

You can control it fully by software.


For example you want to have another kernel you configure David-65 to use internal flash for memory region $F000 to $FFFF.

Now always when 6502 CPU access this memory region it will get bytes from internal David-65 flash. All other regions are normal as without David-65 (external, - from David-65 sight).


Another example: You can also configure to use first 32K David-65 RAM, upper memory is write protected David-65 RAM (as ROM replacement) and I/O and screen memory comes from external (your normal environment).



In case David-65 works in your floppy disk drive (1541): IO will be external to control drive, but all other memory come from David-65.

Every time a read access occurs, 1541 will always read a whole track. If a sector to read which is already in RAM, it works like a RAM Disk (super fast).

Write access to the 1541 drive alway goes into RAM. If drive isn't busy it will save written sectors to disk (lazy write).

If there is a game or program which won't work with this speeder, David-65 can kill itself fully, so it is a normal 1541 and this game will work again.

You can switch between different DOS versions and floppy kernels by simple commands: for example normal DOS, Jiffy, SpeedDOS, Dolphin DOS ...