COMMODORE VIC-20 Pi1541 + 35KB (27+8) RAM EXPANSION CARTRIDGE

Hello,

This is a tested and working project. (Tested on a NTSC Commodore VIC-20 plugged to a C64 PSU and Raspberry Pi Zero)

COMMODORE VIC-20 Pi1541 + 35KB (27+8) RAM Expansion Cartridge is an Easy DIY project, all components are through hole, marked on the PCB, Easy to solder, Easy to make ;)

This PCB is a combination of two independent projects, one of them is Pi1541 (Commodore disk drive emulator) and the other is Commodore VIC-20 35KB (27+8) RAM Expansion Cartridge. They can be used separately or both together.

Pi1541 is a real-time, cycle exact, Commodore 1541 disk drive emulator. You can load and save programs, D64 .PRG ... extensions games/software from a Micro SD card, it is an alternative to SD2iEC, please look at the Documentation link.

The source page link of this PCB drawing is below. (Option A)

https://cbm-pi1541.firebaseapp.com/

Do not forget: solder 2 x 20 pin female header before OLED display :)

Isolate the back side of the OLED display from touching the PCB solder points.

SETTINGS FOR Pi1541 HAT DISPLAY PIN ORDER:

For VCC-GND-SCL-SDA Displays; short VCC + VCC

For GND-VCC-SCL-SDA Displays; short GND + GND

At the back of this PCB.

Many thanks to Stephen White for Pi1541. You can visit his site and make a donation.

More information about Commodore VIC-20 35KB (27+8) RAM Expansion Cartridge:

https://www.pcbway.com/project/shareproject/COMMODORE_VIC_20_35KB_27_8_RAM_EXPANSION_CARTRIDGE_a2f375ab.html

Many thanks Ruud Baltissen from Netherlands for VIC-20 35KB (27+8) RAM Expansion Schematics.

If you want to use Pi1541 without being inserted into the cartridge port then you need to supply DC +5V power to the Pi. (DO NOT CONNECT EXTERNAL POWER SOURCE TO RASPBERRY PI WHILE IT IS INSERTED INTO COMMODORE VIC-20)

JP1 is for cutting the 5 Volts line between the RAM part and the Pi1541 part. In normal use, JP1 header cap is attached. If you remove the JP1 header cap, the Pi1541 will stop getting power from the Commodore.

Please choose "Edge connector YES and Bevelling Yes (45°)

COMPONENTS for RAM EXPANSION part:

62256 DIP28 (32KB STATIC RAM)

6264 DIP28 (8KB STATIC RAM) (You can use 62256)

74LS21 DIP14

2PCS. DIP28 WIDE IC SOCKET

DIP14 IC SOCKET

8P DIP SWITCH (You can use 2x8 Pin 2.54mm pitch male header and 8pcs. jumper caps)

8 PCS. 1/4 WATT 10K OHM RESISTOR

3 PCS. 100nF CERAMIC CAPACITOR

220 μF 16V ELECTROLYTIC CAPACITOR

RIGHT ANGLE TACTILE BUTTON (For RESET Button)

COMPONENTS for Pi1541 part:

Raspberry Pi Zero

Fat32 formated Micro SD Card

5 pcs. Right-Angle Tactile Push Button

4 channel. bidirectional logic level converter

6 pin Male DIN Connector

6 PCS. 30cm Male-Female Duppond Cable

6pin Male Header 2.54mm pitch

0.96 inch Oled Display (Isolate the back side of the OLED display from touching the PCB solder points.)

2x20 pin female header

Passive Piezo buzzer HPM14AX or similar (Optional, Pi-Zero 1541 currently does not support buzzer function.)

2pin 2.54mm male header (for JP1)

Header jumper cap (for JP1)

470 ohm 1/4watt RESISTANCE (value changes leds brigtness)

Red LED

If you have a programmer capable of testing IC chips, such as the 74LS series and static RAM chips, you should remember to test them before soldering. Some chips may be defective. (TL866 Minipro Programmer can test some logic ICs and static RAM chips)

In order to protect your electronical devices, always turn off your Commodore before connecting or disconnecting the cables or any other device.

If you want to use Pi1541 without being inserted into the cartridge port then you need to supply DC +5V power to the Pi. (DO NOT CONNECT EXTERNAL POWER SOURCE TO RASPBERRY PI WHILE IT IS INSERTED INTO COMMODORE VIC-20)

Do Not use HDMI output of Raspberry Pi with this Pi1541 HAT !

JP1 is for cutting the 5 Volts line between the RAM part and the Pi1541 part. In normal use, JP1 header cap is attached. If you remove the JP1 header cap, the Pi1541 will stop getting power from the Commodore.

While transfering data (reading or writing) from SD cards it should not be interrupted like power-off or Reset systems. Otherwise that may damage SD cards.

Gerber files and component list are subject to change without notice. Before paying for the PCBs, be sure to update your orders!

As you can see I have uploaded many projects and I am still working on new projects. If you have any questions, please look for answers online. Unless I specify explicitly, all my projects are tested and confirmed to work under normal circumstances before being shared. I'm sorry I didn't have enough time to answer all the questions.

Use this PCB at your own risk !

Have fun

Thank you.