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Technical detailsoHistory - Key combinations - Floppy commands


One of the coolest parallel speeders available for the 1541 which can speed up floppy operations by up to 200-fold! Roßmöller was well known for their innovative products and the TurboTrans is certainly one of the most advanced floppy speeders at all. The TurboTrans, released in summer 1986, is both a caching system as well as a ramdisk, which can hold two disks in RAM at a time (one disk with 256k version).
The factory population of 256kB DRAM can be upgraded to 512kB and the TT's extra socket can be used for either an 8k CMOS RAM or a 16k EPROM. The TurboTrans was available both as a standalone version as well as an upgrade version for the TurboAccess, a parallel system from the same company. If you have the right PCB for the expansion port, the TurboTrans system can control up to two floppy drives (this of course needs a TT for the second floppy).

TurboTrans does also work with the C128 in C128, C64, and CP/M mode; this requires a small adapter in the C128 [1]. 1541c support was available in March 1987 [2].

[ Help! The TurboTrans is said to be upgradable to a 2MHz-CPU. Can anyone confirm this? ]
[ Help! If you have the TT as an upgrade kit for the TurboAccess, please mail me! ]


1. The original (version 2.7)

The TurboTrans is based on a nearly unmodified TurboAccess. Therefore, it does not remap the function keys, but uses control key combinations for the various extra functions, too. This version (which was the first version tested by the 64'er [1], that's why I call it 'original version) needed ca. 30 seconds to read a complete disk into RAM. Alas, despite the TT's coolness, this is not as fast as Dolphin DOS. Once it is stored in RAM, it is of course much faster - up to 200 times [1].
Version 2.7 has a bug which can lead to crashes: The NMI button (if one is attached) is not debounced. This has been fixed with version 3.0.

2. Version 3.0

As of Version 3.0, you cannot use an extra 16k EPROM anymore, it must be equipped with an 8k CMOS SRAM. Due to the enhanced maximum disk capacity (41 tracks, 196kB), the DRAM cannot hold the extra buffers, etc. so that these have to reside in the extra SRAM. This version copies a complete disk into RAM in 21 seconds. This version could also work in 2MHz mode [1], which makes the TT read a complete disk within 16 seconds.
Note that with TT 3.0 you can format disks with up to 41 tracks. You can specify the number of tracks in the format command:
where xx = number of tracks.

Alas, with this version, Roßmöller started to save a few cents and removed the multipin connector, the pull-up resistor for the NMI switch and the NMI switch itself. You can easily post install these, though.

3. Version 3.4

ROMs: Floppy [32k] and Kernal [8k]

I have this version, but I did not notice any differences to prior versions. Did you?

TurboTrans Plus

TurboTrans Plus is an extension of the standard TurboTrans. It offers a mini monitor, DOS 5.1, reset extensions, and many enhancements for the Commodore BASIC and the screen editor, which are actually standard in other speeders or cartridges. This extra functionally required removal of the RS232 routines, though.

Key Combinations

All key combos are of the CTRL-X type, where X is one of the following keys:
Show directory
Load BASIC program from directory.
Load machine language program from directory.
Print the error channel. As of version 3.0, you will get two numbers at the end of the status message, where the first number means the number of tracks, and the second number the currently selected RAM bank (0 or 1).
If you press Ctrl-O in the directory, it prints ..."S:name". If you press RETURN then, the file will be deleted.
Low resolution hardcopy.
Switches the standard floppy address between 8 and 9.
BASIC ReNEW. Restores programs after Reset or NEW.
Halts the C64 so that you can switch off the TT. After switching to the original ROM, press @ to continue.
Note that there is a 'bug' in TT: If you press one of the CTRL key combos at the bottom of the screen, the C64 will still slow down scrolling as it normally does as long as the CTRL key is pressed.

Floppy Commands

The following commands can be entered with OPEN15,8,15,"command":CLOSE15. Note that Ctrl-O will print OPEN15,8,15,", so that you just have to type Ctrl-O, then the command, followed by ". Maybe you can leave out the final ", I have to try that yet.

Defaults are in brackets.

 Command        | Function
 D:R=D or D:1=0 | load disk into RAM (can be done by a switch)
 D:D=R or D:0=1 | write RAM to disk

  The : for the D: command has been dropped as of version 3.0.

 T+             | activate RAM
 T-             | deactivate RAM
 SW             | swap RAM banks (can be done by a switch)
 SW1            | select RAM bank #1 (version 3.0 only)
 SW2            | select RAM bank #2 (version 3.0 only)
 ST             | get status (can be read with Ctrl-/)
 N1:name,id     | format ramdisk #1
 N2:name,id     | format ramdisk #2
 N:name,id,xx   | format disk with xx tracks (xx = 35-41)
                | 41 tracks is only possible with version 3.0 (?)
 E:name         | change disk name
 E:name,id      | change disk name and disk ID
 L:name         | write protect file(s)
 F:name         | unprotect file(s)
 B:name         | fill filename(s) with blanks
 K:name         | remove blanks from filename(s)
 UX:BUMP        | adjust r/w head to track 1
 A+ / A-        | motor spin on disk insertion [on] / off
 G+ / G-        | [fast] / slow head movement
 V+ / V-        | write verify [on] / off
 L+ / L-        | 20-fold fast load [on] / off
 UX:TA          | switch to TurboAccess mode (can't switch back)
 UX:RDD1        | BAM oriented reading routine (slow)
 UX:RDD2        | backup reading routine (fast) [default]
 UX:WRD1        | BAM oriented writing routine (slow)
 UX:WRD2        | backup writing routine (fast) [default]
 UX:NMI1        | normal 1541 NMI routine
 UX:NMI2        | copies the 1541 zeropage into RAM (bank 300-307) on NMI
 UX:NMI3        | TT NMI routine (points to 'copy disk into RAM') [default]
 X:             | jump $a000


[1] 64'er 7/86, p.45, Schnell - schneller - TurboTrans
[2] 64'er 3/87, p.15, TurboTrans endlich billiger!

Updated: February 20th, 1998
Created: December 3rd, 1997
Thanks to: Maurice van Hooijdonk for sending me a copy of the manual!

Site copyright © 1997 by Marc-Jano Knopp
This document is part of MJK's Commodore 64 & LCD Page
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