1541 Ultimate

Technical Info
ROM	2 MB flash
RAM	32.5 MB (first batch 16.5MB)
Hardware features	3 Buttons - Freeze, Reset and 1541U Freeze (menu) SD card slot IEC bus connector
Manual	PDF: 28 pages from 1541ultimate.net PDF: 2 pages scan of suplied documentation sheet
CRT ID	None
Programming	See 1541ultimate.net

The cartridge described in this article is under constant active development - for recent news and data please check: 1541ultimate.net

1541U is one of the ultimate cartridges for the C64 and regular checks at 1541ultimate.net are a strict requirement for any C64 cartridge lover. It started in 2008 as a hobby project by Gideon Zweijtzer, who then founded the company "Gideon's Logic Architectures" in January 2009.

Since the 1541U emulates a range of freezer cartridges and allows re-flashing them it is a perfect platform for testing ROMs on the real machine. Cartridge emulation is pretty good and should suit most requirements. This emulation also made the 1541u enter the charts here. There are some problems left as with any other hardware but since this baby can be updated and firmware is publicly available we see a bright future for it.

Following info mostly from the 1541Ultimate Website:

Features

The following are the features of the FPGA core, for hardware features see below. Not all features may be available in all versions of the firmware and/or hardware!

1541Ultimate

1541Ultimate-I

1541Ultimate-plus

This 1541Ultimate-I (-plus) with ethernet found an awesome home. (Click image for more info.)

1541Ultimate-II

The new 1541U-II board

• C64 cartridge emulation (also see CRT_ID):
  • generic 8k/16k game
  • Final Cartridge III
  • Action Replay
  • Retro Replay
  • Super Snapshot
  • Ocean (fw 2.x)
  • Epyx FastLoad (fw 2.x)
  • Easyflash (no write support, fw 2.x)
  • Magic Desk (fw 2.x)
  • C64GS (fw 2.x)

• Flexible freezer menu
  • select, mount, create D64 images, browse disk images
  • create new directories, delete files
  • Ultra fast DMA load of single file programs (directly from SD / from a .D64 with automount and from a .T64 file)
• Configuration screen, with resident settings

• Full emulation of a real Commodore 1541 diskdrive. (two drives on 1541U-II)
  • Uses .D64 files stored on SD card
  • Supports .G64 files as well (Read only on fw pre 2.x)
  • Configurable ID
  • Configurable ROM (1541/1541C/1541II or custom)
  • RAMBOard memory expansion (16K)
  • Drive Noise emulation that works with eg 1541-Music or Drive Composer
• Secondary 'IEC-drive' for direct access to FAT filesystem
  • Can be used in stand alone mode to mount disks into the emulated 1541.
• FAT/FAT32 support, with sub-directories and long filenames
• Supports SD V1.1 cards as well as SD V2.0 in High Capacity mode (SDHC)
• USB storage device (stick, card reader, and even HD) (1541U-II only)
• ISO9660 support with Joliet, for reading .ISO files and access external CD/DVD drives through USB (1541U-II only)

• Load of last disk on power up

• 'Stand-alone mode' (1541U-I fw 1.7)
  • keeps the cartridge port free
  • powered through Mini-USB connector
  • controlled through buttons and IEC.

• Commodore 1750/1764 REU emulation (1541U-plus, 1541U-II)
  • Size selectable from 128K up to 16 MB
  • Can be combined with Retro Replay and Super Snapshot compatible roms

• RR-NET compatible ethernet (1541U-plus version only, fw 1.x only)
  • *NO* Ethernet support yet in stand alone mode!

• Dual SID implementation, optionally 8 voices each (1541U-II only)

• Built-in SID player; plays SID files on either 'real' SID or emulated SID. (fw 2.4)

• PCM output ("Ultimate Audio") (1541U-II only, fw 2.5)
  • Up to 7 voices of sampled audio simultaneously accessible through I/O space
  • 8- or 16-bit samples, up to 48 kHz sample rate

• Built-in copier (fw 2.6)
• Command Interface, Accessible module through I/O space that allows direct commands to Ultimate-II (fw 2.6)
• Ultimate-II DOS V1.0, I/O space driven direct file access to SD/USB (command target) (fw 2.6)
• Kernal replacement function (fw 2.6)

• Tape emulation, through 6-pin header on the bottom of the board (requires additional tape connector, fw 2.x)
  • Load .TAP files to C64
  • Capture tape data from a datasette and store it as .TAP file and write .TAP files back to tape, using a Commodore tape deck

Hardware Specifications

The basic hardware platform went through 3 revisions so far:

1541U

this describes the first version of the hardware, produced from 2008 to end of 2009.

• Board size: 68 x 100 mm
• 250k-gate FPGA
• Full size 6-pin DIN connector (IEC)
• 512 kB SRAM
• 2 MB Flash ROM
• 16 MB SDRAM
• Full size MMC / SD card compatible (Mini/Micro SD possible with adapter)
• Stereo audio output
• 6-pin expansion pin-header for connection to tape port (for C2N emulation), or other future features.

1541U-plus

as above, with the following differences:

• 32 MB SDRAM (+16MB for REU)
• CS8900a ethernet interface (optional since second batch)

Note: only a small number non-plus boards (with just 16MB RAM) was produced, all later boards were -plus boards.

1541U-II

this describes the current version of the hardware, produced since 2010.

as above, with the following differences:

• Board size: 62 x 84 mm (about 30% smaller than the 1541U)
• Sturdy plastic case, enforced with glass fiber
• 700k-gate FPGA
• MicroSD card compatible slot (instead of a full-size SD)
• USB host port (supports Mass storage class only)
• real-time-clock function, for correct file time and date
• ethernet was removed from the hardware

1541U-II+

slightly revised hardware, available since september 2016.

• Sturdy ABS plastic case
• Slightly bigger and faster 1M-gate FPGA
• 5 MB Flash ROM
• 64 MB DDR2 SDRAM
• SD card slot was removed
• Improved Audio codec (24 bit/96 kHz, for sampled sounds and SID emulation)
• Full size 6-pin DIN connector (IEC)
• Audio input added (currently not yet used)
• Speaker built in
• 100Mbps Ethernet adapter built in (NOT yet CS8900a/RR-Net compatible)
• Micro USB for external power
• Three USB host ports
  • Specialty USB 3.0 port with USB 2.0 signals for storage device OR cable to tape adapter board (for C2N emulation), or other future features.
  • revised tape-adapter, connected via a USB port
• Dual Flash (no more worry that a software bug or upgrade failure leads to a bricked device)

Known Problems

Please understand that due to the nature of FPGA based hardware, many problems might get fixed with a firmware update at some point. For this reason we list only "persistant" problems here, like actual hardware bugs or long standing firmware bugs. For details please refer to the 1541 Ultimate website.

1541U

Freezer bug

There have been long standing issues with the freezer logic, affecting both emulated cartridges and the menu system. Common symptoms are freezer not reacting at all (perhaps connected to DMA loading), or crash when returning from the freezer to the running program.

see [1] (requires registration)

Ethernet bug

This is a hardware problem with the -plus version of the 1541U board. When the CS8900a chip is enabled, the RAM under the i/o area can not be accessed correctly, which makes some operations impossible (such as transferring binaries to that area using codenet) "Ethernet will never work 100% on the 1541U-I for ALL C64's out there. This is bus-timing related and could only be fixed if some of the timing is revised and other concessions are made."

see [2] (requires registration)

1541U-II

see 1541U-II Bug List local copy (retrieved 19 Mai 2014)

Cartridge problems

• regular 8k-game and Ultimax cartridges do not work
• when an unsupported CRT file is loaded, the menu program shows a message, and then the fpga core locks up, requiring a power cycle.

1541U-II+

see 1541U-II+ Bug List (requires registration)

Documentation

1541U

• Quick Guide to the 1541Ultimate - official "quick guide" that came with the device
• 1541Ultimate User Guide 0.15 Concept3 - unofficial user manual created by N.A. Hoijtink (refers to fw 1.x)

1541U-II

• Quick Guide to the 1541Ultimate-II - official "quick guide" that came with the device
• 1541Ultimate-II FW2.6k quick reference
• 1541Ultimate-II Technical Reference v0.3 - includes instructions on how to setup the build environment
• 1541Ultimate-II command interface v1.0
• 1541Ultimate-II "ultimate DOS" - register API v1.0
• 1541Ultimate-II "ultimate Audio" - register API v0.2
• 1541U remote settings - unofficial guide to setting up "putty" for telnet

1541U-II+

• Quick Guide to the 1541Ultimate-II+ - official "quick guide" that came with the device
• MPS Printer Emulation Guide v1.0

Firmware

1541U

Since some time official builds of the most recent firmware are no more provided for the (old) 1541U board. Please note that all these archive contents were available from 1541ultimate.net and even though chances are slim, newer versions may be available there!

• 1541u1_2.4a.zip (15 January 2012) - first port of the new 2.x firmware, NO support for ethernet! (note: this is the same as 2.4c, except the updater program itself)
• 1541u_Firmware_v17beta.rar (19 August 2010) - includes 1541u-firmware-v17b.pdf and 1541u_v1.7beta.zip
• 1541u_Firmware_v16.rar - includes 1541u-firmware-v16.pdf and 1541u_v1.6.zip
• 1541u_Firmware_v15.rar - includes 1541u-firmware-v15.pdf and 1541u_v1.5.zip

unofficial

• 1541U1-25-kcs.zip (4 May 2016) - 2.5 Firmware with fixed KCS support, compiled by rgc
• 1541-Ultimate-MK1-2.6d.o918r4.zip (7 November 2013) - Obliterator918′s custom 1541 Ultimate Firmware for “mark 1″ units, Version 2.6d.O918.4 Based on Gideon’s SVN revision 131.
• 1541u1_172b_with_wvl_fixes.zip (12 December 2010) - 1.72b with WVLs config save flash indication and P00 support, patched with the Ultimate-freezercode from 2.0 firmware (demos like Another Beginning and We Are New now works) and added the (Blu)REU-imagesupport. by Tommi Lempinen

1541U-II

Please note that all these archive contents are available from 1541ultimate.net and newer versions may be available there!

• 3.2 Update_3.2.u2u.zip (2018/2/11) (ONLY FOR U2, NOT U2+)
• 3.0 final (build 417) 1541u2_3.0_417.zip (ONLY FOR U2, NOT U2+)
• 3.0beta7 with Tape fixes (11 August 2016) 1541U2_3_0BETA7TAPEFIX.zip (Install the normal V3.0 BETA 7, then RUN the update.u2u file to install the tape loading patch)
• 3.0beta7 with MPS printer support (28 June 2016) Ultimate-II-3.0b7-MPS-Printer-beta-3.zip
• 3.0beta7 (15 April 2016) 1541u2-Firmware-3.0beta7.zip
• 3.0beta5 (10 October 2015) 1541u2-Firmware-3.0beta5.zip - including short manual
• 3.0beta4 (29 September 2015) 1541u2-Firmware-3.0beta4.zip - including short manual
• 2.6k (20 October 2014) 1541u2_2.6k_audio.zip (audio version, single drive), 1541u2_2.6k_dual_drive.zip (dual drives, no audio)
• 1541u2_2.6h.zip (10 August 2013) - two floppy drives, no SID emulation
• 1541u2_2.6d.zip (12 February 2013) - this firmware has the "ultimate audio" enabled, SID emulation, but emulates one floppy drive only.
• 1541u2_2.6.zip (03 February 2013)
• 1541u2_2.5.zip (03 February 2013)
• 1541u2_2.5_uaud.zip (03 February 2013) - this firmware has the "ultimate audio" enabled, but emulates one floppy drive only.
• 1541u2_2.4c.zip (15 January 2012)

unofficial

• 1541u2_3.0c_433._v4.zip by markusC64 (Support for Business Basic CRT files, Retro Replay CRT files can be used without patching them before)
• 1541u2_3.0c_433._v3.zip by markusC64 (This version enables a second virtual 1541 drive on the 1541 Ultimate II) - Update to 3.0 final first if you're currently using firmware 2.x.
• 1541U2-26k-KCS-21.zip (2016/04/29) - 2.6k update with fixed KCS (bload) compiled by Rene Garcia
• 1541U2-26k-KCS-20.zip (2016/04/19) - 2.6k update with fixed KCS (bload) compiled by Rene Garcia
• 1541 U II 2.6k - Unofficial Horrocks Update 4.zip (2015/07/24) - 2.6k update compiled by david horrocks
• 1541 U II 2.6k - Unofficial Horrocks Update 3.zip (2015/05/05) - 2.6k update compiled by david horrocks
• unofficial_2_6k_d64fix_horrocks_update2.zip (2015/02/04) - 2.6k update compiled by david horrocks
• unofficial_2_6k_VIA6522_horrocks_update1.zip (2015/02/02) - 2.6k update compiled by david horrocks
• 1541U2-update26j.zip - 2.6j update compiled by paranoid64
• 1541U2-25x-KCS-11.zip - modded firmware 2.5x with final cartridge 1&2 and KCS power cartridge support (with bload bug). by Rene Garcia

1541U-II+

Please note that all these archive contents are available from 1541ultimate.net and newer versions may be available there!

• 3.2 update_3.2.u2p.zip (2018/2/11) (ONLY FOR U2+, NOT U2)
• 3.1 1541u2p_3.1.zip (ONLY FOR U2+, NOT U2)

USB fixes:

support for sticks that do not reliably reply to the 'inquiry' command

Byte alignment issue fixed when writing. This caused corrupted G64s to be written sometimes

Support for composite devices added

Added support for USB keyboards, to navigate the Ultimate browser menu

Incorporated patches from Markus & Henning, including, but not limited to:

Audio squeal fix, speaker volume addition

Ultimate DOS V1.1 with added commands

Added Home Directory support

Added support for GeoRAM

IEC fixes

IEC now operates properly on the bus, when it is alone (disabled 1541 drives)

IEC filename fixes; saving a file to IEC adds the right extension and also removes the extension when loading directory

IEC should now work with JiffyDOS (not yet supporting the JiffyDOS protocol)

UltiCopy is working again!

Small fix in TCP support (TCP hangup on retransmission)

Other small fixes

Save disk twice bug fixed

Fixed load errors on tape adapter cable with some USB 3.0 cables

Keyboard "racekeys" fixed

Reduced Link Up time for the Ethernet port

Ultimax mode ROMs now allow video data in ROM

• 3.0c (build 424) 3.0c_424.u2p.zip (ONLY FOR U2+, NOT U2)
• 3.0 (build 417) 3.0_417.u2p.zip (ONLY FOR U2+, NOT U2)

unofficial

• 3.0c_433._v4.u2p.zip by markusC64 (Support for Business Basic CRT files, Retro Replay CRT files can be used without patching them before)
• 3.0c_433._v3.u2p.zip by markusC64 (This version enables a second virtual 1541 drive on the 1541 Ultimate II+)
• 3.0c_433._v2.u2p.zip by markusC64 (Updated Retro replay modules to 3.8q resp. 3.8y)
• 3.0c_433._v1.u2p.zip by markusC64 (Simons' Basic can be loaded from CRT, Comal 80 can be loaded from CRT, Westermann learning modules can be loaded from CRT, GeoRAM cartridge support)

Software supporting special features

Listing software that requires one or another special feature only available on "modern" hardware and/or emulators, such as the 1541U, Chameleon or VICE.

16MB REU

• bluREU by Crest
• NUVIEmaker v0.1e by Crest
• Limon REU wave player v2 v3.0d by Data
• REU Wave Player v1 (PoC) by groepaz
• TAP writer 0.2 > 512 KB TAP writer v1.04 by Enthusi

Note: 16MB REU is also implemented by the Chameleon and can also be emulated by VICE.

Ultimate Audio

"Ultimate Audio" is a custom 7(?) channel PCM output, which is available in 1541U-II Firmwares 2.5+

• UltimateAudio simple synth by Freshness
• Ultimate Audio MOD Player by Freshness
• Rush by Singular (also requires "Ultimate DOS", fw 2.6+)

Ultimate DOS

"Ultimate DOS" is a custom command interface for accessing files on the SD card, which is available in 1541U-II Firmwares 2.5+.

• Ultimate Opus V0.2 by LFT
• Sidplay64 v0.9 by SHAPE
• ultimateii-dos-lib by xlar54 is a cc65 library for accessing the DOS functions of the Ultimate II+ cartridge

Notes

• codebase64.org has "How the 1541U freezer works" or "Safely freezing the c64" by Gideon Zweijtzer
• Commodore Free Issue 35 has an interview with Gideon Zweijtzer
• Lotek64 Issue 26 has a german review on the 1541 Ultimate

• Wikipedia deleted the page on the 1541 Ultimate (twice actually). Due to "Unambiguous advertising or promotion" the last time. Well - WiPeD 1541 Ultimate tries to recover it.

Weblinks

• 1541ultimate.net - project website and user forum (requires registration)
• official FAQ
• Quick Guide to the 1541 Ultimate.zip at Goin' for Gold and mags.c64.org
• 1541U source code repository - svn co https://xp-dev.com/svn/gideonz_1541Ultimate/ gideonz_1541Ultimate (note: this does NOT include the FPGA core!)
• 1541U-II source code repository - svn co https://xp-dev.com/svn/1541UltimateII/ 1541UltimateII
• David Horrocks github
• markusC64 github
• 1541U-II Wish List (requires registration)
• 1541U section on Forum64 (german)
• 1541U on Facebook (requires registration)
• 1541U on c64-wiki.de
• DIY case for the 1541U1
• Firmware list and downloads (by Mr.Ammo)