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Commodore VIC20 in FPGA

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Dec 072011

For some time now I’ve been watching the fpgaarcade website and have even bought some of Mike’s replacement C64 PLA chips.
Recently I got my hands on a Spartan 3E FPGA development board and thought id try out Mike’s FPGA implementation of the VIC20.

Following the instructions provided it was a breeze compiling and transferring the VHDL.
Plugging in the VGA cable and setting the on board switches to 31khz I was greeted with

On my monitor here the screen is offset slightly but im told another monitor may yield better results.
The Spartan development board also has a PS/2 port which when I plugged in a keyboard was able to use the VIC20 as I would a real one.

This thing is so good that I can even upload 4 converted cartridges into the on board flash memory and run them at the flick of a switch. Once I get my serial cable built ill try that out too.

Now, on with learning VHDL, its not going well.

All credit goes to Mike at FPGA ARCADE

EDIT: Got a serial cable made up and flashed over the Jupiter Lander game as described with the VIC20 VHDL source, works pretty well.

PLS100 chips

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Nov 232011

Today I received a job lot of 20 x PLS100 chips that I got from eBay recently.
For those that aren’t aware, these are what was used as a PLA in the older breadbin Commodore 64’s and are probably the most common failure in the machine as they tend to run hot.
Ive got the JEDEC fuse map from a genuine C64 PLA and have tested with no problems. These should keep mine and RCM’s Commodore’s going for a while longer now

C64 breadbin JiffyDOS dual boot

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Nov 122011

Today I finished my adapter to make a breadbin 64 accept a 27C128 EPROM.
The standard kernel ROM is a 2364 pinout and is 64Kb. To fit both the original kernel and the JiffyDOS kernel on obviously we need a ROM twice the size.
The problem is the 2364 is not compatible with any EPROM pinout unlike the C64c so this adapter is necessary.

I used 2 turned pin sockets, a 24 pin and a 28 pin one.

On the 28 pin socket cut pins 20, 23 & 26 short,not completely off but short enough not to make contact with the pins on the 24 pin socket when pushed together.
Connect pin 1 to pins 27 and 28
Connect pin 14 to pin 20

Get the 24 pin socket

Connect pin 28(VCC) of the 28 pin socket to pin 24 of the 24 pin socket
Connect pin 2 of the 28 pin socket to pin 21 of the 24 pin socket
Connect with 23 of the 28 pin socket to pin 18 of the 24 pin socket
Attach flying leads from pins 14, 26 and 28 of the 28 pin socket, these will go to your switch.
You can also fit a 4.7k resistor between pins 26 and 28 which means you don’t need that extra flying lead from pin 28 to the switch, just makes it that little bit easier.
Mash the two sockets together lining pin 14 of the 28 pin socket to pin 12 of the 14 pin socket.
Fit your 27C128 eprom and you should be good to go.

My first attempt works well but isn’t the neatest. If I make another and I almost definitely will, it will be neater.

C64 Easyflash cartridge

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Nov 102011

Got a little free time today to mess with my Easyflash cartridge for the Commodore 64.
The main reason for getting this was to play Prince of Persia but its a fantastic device that ill be using for playing many games.

Mine came with the new Prince of Persia game already flashed onto it but wanted to have a play around myself.
The reprogramming is all done via the C64 itself using the Easyprog program so no external programmer is required although an SD device is highly recommended.

If your using an SD2IEC device then the Fastloader option needs to be disabled in the OPTIONS menu or it will hang at this screen (thanks for the heads up Steve).

My mate Stiggy has already written a nice little writeup on this device and he stated that flashing a file took him just under 40 minutes. Not totally sure how big the file was but I tried to copy Last Ninja 1 & 2 over which is 882KB and using JiffyDOS took just under 10 minutes.

After this the game loads pretty much like you would expect from a normal cartridge. Im very impressed with this thing. Now to find more goodies to try out.

Loading times with JiffyDOS

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Oct 302011

This post is mainly to make Stiggy drool a little.
It shows the loading times difference between the standard C64 kernel and JiffyDOS using the SD2IEC.
The videos show Last Ninja 2 loading from the FB64 program on a C64c. Try to ignore all the crack screens etc and take note of the actual loading screens.

Standard C64 kernal

Using JiffyDOS

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