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BMC64 | BMC128 | BMVIC20 | BMPLUS4 | BMPLUS4EMU (Pi3)BMPET

BMC64 is a bare metal fork of VICE's C64 emulator optimized for the Raspberry Pi. It has 50hz/60hz smooth scrolling, low video/audio latency and a number of other features that make it perfect for building your own C64 replica machine. For more details visit the github link below.

v3.4 - Pi3 Fast Resampling, Custom GPIO & more

Kernel Patches:

  • Pi 3B+ was producing noise for sound. Problem is fixed in updated 3.4 archives. Please update your kernels if you have this issue.
  • Keyboard was not working on C128 in CP/M mode. Problem fixed in updated 3.4 archives. Please update your C128 kernel if you have this issue.
  • Same issue above was causing Dolphon DOS to fail. Latest 3.4 should fix that too.
  • Two GPIO pins were used twice in GPIO Config #1 by mistake. GPIO 23 and GPIO 19.
    Fire button was shared with the toggle for virtual keyboard.
    Down joystick port would have pressed cursor down.
    If you had this issue, please replace your kernels with the latest from the archived files.
See CHANGELOG for latest changes

BMC64 is a bare metal C64 Emulator (using VICE) for the Raspberry Pi (Models 2 & 3). There is no bloated O/S to boot and the emulator has direct access to hardware resulting in better performance than the Linux based distributions. VICE dependencies are satisfied using circle-stdlib. An option to switch to VIC20, C128, PLUS/4, PET models is included in v3.3+

GitHub Link: https://github.com/randyrossi/bmc64 Please review the README.md file for complete docs on BMC64

Features

  • Quick boot time: 4.1 seconds! (over composite)
  • True 50hz/60hz smooth scrolling (no horizontal tearing or jitters!)
  • Low latency between input and audio/video
  • Excellent audio/video synchronization
  • No need to issue a shutdown sequence, just power off
  • Supports wiring real joysticks and a keyboard via GPIO pins (optional) Click Here for adapter build instructions
  • Supports a PCB for scanning a real C64 keyboard and joysticks for embedding a Pi inside a C64 shell (optional)
  • BMC64Lite version is also included for the Pi Zero. See BMC64Lite Info Page for how 'Lite' versions differ.

Downloads

BMC64 3.4 Release

NOTE: Since Version 3.0, all supported machines for all supported Pi models are distributed in one release image.

You have two options for installation:

1) format a FAT32 SD card and/or partition and unzip bmc64-3.4.files.zip onto it. The Pi will boot from the first FAT partition. See below for ROM files you will need to provide yourself.

OR

2) flash an image using bmc64-3.4.img.zip (300Mb partition). Again, see below for additional ROM files you need to provide.

BMC64 Setup

  • Formatting an SD card
    • sudo fdisk /dev/sdb (make SURE /dev/sdb is the SDCard!)
    • Create your partition(s)
    • sudo mkfs.vfat /dev/sdbx (make SURE /dev/sdbx is the right partition!)
  • Burning an image to SD card
    • Linux: sudo dd if=bmc64-3.4.img of=/dev/sdx bs=64k (make SURE /dev/sdx is correct!)
    • Windows: Use etcher or Win32DiskManager
  • You MUST obtain at a minumum Commodore 64 KERNAL, CHARGEN, BASIC, and d1541II rom files and copy them to the sdcard into the C64 folder. The emulator will not run without them. These are available from many sites.

    • Example

      NOTE: You will have to rename files from the names you find here to the names the emulator expects above. For example, characters.901225-01.bin becomes CHARGEN. This is what your C64 dir should look like:

  •                     /C64
                           kernal
                           chargen
                           basic
                           d1541II (recommended)
                           rpi_sym.vkm
                           bootstat.txt
                        /C128
                           See BMC128 details page
                        /VIC20
                           See BMVIC20 details page
                        /PLUS4
                           See BMPLUS4 details page
                        /PLUS4EMU (Pi3 Only)
                           See BMPLUS4EMU details page
                        /PET
                           See BMPET details page
                    
  • Other disk drive ROM files are optional (dos1541, dos1571 and dos1581)
  • Copy to your SD card your .D64/.TAP/.CRT files to the disks, tapes, or carts folders.
  • All USB devices must be attached before you power on the PI. They must remain plugged in or the emulator will not function.
  • F12 brings up the menu (or Commodore Key+F7 if enabled)
  • README for more details.

BMC128, BMVIC20, BMPLUS4, PET

These machines are now bundled with the main BMC64 release v3.3 or higher. Refer to the tabs above for those machines on how to setup their ROM dirs.

Stats (C64 Machine)

The following end-to-end latency measurements were reported by _ C64 CUSTOMS _'s video "C64 Hardware -TheC64 mini Input Lag Test" video

https://www.youtube.com/watch?v=b73BONBBZR8

Note: These measurements are specific to his monitor/TV and joystick testing program he used.

Machine/Emulator over HDMILatency (Machine)Latency (Machine + Display)Notes
Real C64 +
Framemeister HDMI Upscaler
0ms3 framesHDMI using high speed camera
Ultimate 64< .1ms1-2 framesHDMI using high speed camera.
*Practically all latency introduced by TV/Monitor after scaling since the U64 has no frame buffer.
See video for measurement.
C64 Miniunknown6-7 framesHDMI using high speed camera.

Below are my measurements for composite video/audio out and how they compare to other systems. These and are specific to the joy testing program I used. The joy tester is a modification of the 8-bit guy's key delay test and is included with BMC64. It polls joy port 2 in a tight loop and plays a beep and color change when a button press is detected.

C64 mini/maxi audio measurements were made by The 8-bit Guy.

Since the emulator is operating at the frame resolution, I decided to measure lag in terms of frames rather than ms duration. My definition is as follows:

A lag of X frames means that if the circuit for the button press is closed somewhere within frame 1, the mid-screen transition will appear somewhere within frame X+1.

Button presses will happen mid-way through frame 1. A lag of X means the mid-screen transition caused by delayjoy.crt will appear mid-way through frame X+1. So a lag of 2 frames means the transition will occur somewhere in the 3rd frame. On average you'll get a 40ms delay between button press and transition. Best case possible is 20ms. Worst possible will be 60ms. This does not mean games will necessarily react within 2 frames as the game itself may only poll the joyport once per frame anyway, in which case even with a 2 frame lag, the game may still only react to the input change on the 4th frame.

Oscilloscope pics to support the table below

Machine/EmulatorComposite Video LagAudio DelayNotes
Real C640 frames0msdelayjoy.crt
Ultimate 640 frames PAL Composite~35ms analog audio portdelayjoy.crt
C64 MiniN/A (see below)~320ms8-bit Guy's latest measurement for audio
delaykey.crt
(Was previously 360ms before firmware update)
C64 MaxiN/A (see below)~110ms8-bit Guy's measurement for audio
delaykey.crt
Combian2-4 frames USB Gamepad
3-4 frames Keyrah (DB9)
~250ms analog audio jackUsing default settings (200ms buffer). I was using Fast SID engine. Could go as low as 135ms with buffer size change to 80ms.
delayjoy.crt
BMC642 frames GPIO
2-3 frames USB
3-4 frames Keyrah(DB9)
~90ms analog audio jackProgressive PAL composite for video using oscilloscope, ReSid SID Engine used
delayjoy.crt

* 8-bit guy measured HDMI video lag for the C64 mini/maxi to be around 90ms which would make the raster transition show up somewhere in the 4th frame. I don't have the equipment to measure HDMI lag, only composite.

Thanks!

Special thanks goes out to my friend Ryan Daum for his advice and technical guidance on this project!

© 2019 Randy Rossi (randyrossi at gmail dot com) - All rights reserved (2019/01/30)