Jiffy Dos for the Commodore 64 and 128 are plug in chips that install inside these computers. The main purpose of the Jiffy chips is to increase the disk speed when accessing any type of drive in any mode. As a bonus, several commands are included to ease the burden of disk operations.
Why is there a need for Jiffy? It all goes back to the 4040 drives. Most of the present day CBM Disk Operating Systems have sprung from this older drive. The problem seems to be a lack of a real and fully used drive controller for the 1541 and 1571.
Commodore, with its zest for compatibility of the older units (4040, 2031 & 2040), has kept an archaic DOS and just tacked on some new code for each drive. For these reasons they have slowed down the actual transfer rate inside the drive and on the serial bus.
The Jiffy ROM chip is an overlay for the existing DOS which improves the transfer speed. The actual inner workings and theory were not made available to these writers.
Installation
The UPS delivered tube contained a set of chips for both the drive and computer, installation instructions, and a user manual. Installation requires an average amount of skill when cracking open the computer and drive cases. The C-64, C-128, and 1541 require the installation of an enclosed on/off switch that is mounted on each unit.
The ROMS are all socketed (except older C-64s) and the instructions are well written and include detailed drawings to guide you through each step, with final test procedures to confirm performance. We advise installing the drive chips first, since these are easier than the computer and gives the user a chance to get used to working with the hardware.
Failing to have a size ten torx screwdriver caused several problems getting the heat-sink back in the proper position on the 128. After 45 minutes of frustration, buying the proper size torx driver solved the problem. Many of the newer units are assembled with these torx screws. An inexpensive I.C. extractor is also recommended for a clean removal of the old ROM chips.
A Buck knife proved handy for drilling a hole in the plastic case of the computers and '41 drive for the Jiffy disable switches. The instructions give a 'suggested' location for these switch holes. Stronger wording could be used here, although it could always be said that the empty case hole is for heat dissipation. Be careful if you decide to locate the switch at another location, be sure that it will not interfere with other accessories or with the re-assembly of the case.
Documentation
The 32 page manual is well organized and easy to use and serves both as a C64 and C128 booklet. Lacking is an index, reference card, and Function Key overlay cheat-sheet. The booklet describes every command completely, but doesn't fully explain how Jiffy works.
Usage
Jiffy's enhanced DOS wedge has the normal wedge commands, plus some special features. Both computers access these commands by using the function keys or by typing them in direct mode. This is handy for the C-64, with its "dead" function keys,but cumbersome for the 128. Switching the F3 DIR to F1, F2 DLOAD to F3, and putting the Scratch command where DLOAD was, is not being user friendly! While a disable command is provided for the Function keys it can still be hard adjusting to switching back and forth between stock and Jiffy F-Key definitions. The Jiffy-Dos commands on the function keys are designed to work from the directory listing, giving you a built in menu type system.
Another toggle is for multiple drive users. A Control D toggles you between the drives present on the system. The new default value is printed to the screen and all subsequent commands are sent to this new drive. Jiffy-Dos will not allow the selection of a drive that is not present. If there is only one drive present at power up Jiffy-Dos defaults to it on power up, regardless of device number.
Other commands include an Un-New (basic), locking/unlocking files, screen dump, listing ASCII files without disturbing memory, loading ML files without resetting basic pointers, disabling the '41 head rattles, shifted-run first disk file load and run, and copying/combining files. Some of these commands have oddities, the screen dump (CONTROL-P) is done in uppercase/graphic mode, and does not work in CP/M mode, conflicting with CP/M's use of the same command as a printer on/off toggle. On the other hand, these commands can all be used from a basic program while being chained together and allow command variables.
Compatibility
Any hardware addition to your system raises this serious question. We usually run programs with the Jiffy chips on. What does not work are the following: datacassette, IEEE devices and the Partner cartridge (with the Aprospand cartridge
expander). Just about everything else we tried, works.
Software was another story. Super '81 Utilities and some Electronic Arts games acted buggy, CSDOS failed most commands although ARC in 64 mode works fine, and there were problems with Word Writer. A flick of the Jiffy disable switch remedied these problems allowing the programs to operate normally.
Creative Micro Designs has a 30 money back guarantee if you are not satisfied with the system's compatibility with your software.
Speed
Jiffy Dos really shines in a C-64 or C-128 in 64 mode! Speed increases are most noticeable here with load and save times as advertised. The same is true for the '71 in '41 mode. A nice Jiffy feature with the '71 is the ability to read double sided disks while in the '41 mode. This has eliminated the need for the U0>M1 commands that puts the '71 back into '71 mode. C-64 owners now have a new avenue to explore when shopping for a replacement drive. Formatting, and accessing the '71 drive's second side with a C-64 is a blessing, and can be done with any C-64, with or without Jiffy installed. The '81 speed with the 64 was comparable to using a 128.
The modified 1571 with a C-128 is faster, but not like the dramatic C-64 increase. Several of us that have procrastinated on the '71 ROM upgrade will be pleased to find that writing to the second side of the disk is not as tedious as with the older ROMS. Several of the older ROM bugs have been fixed, too.
I did not see any speedier transfer when using the '81, although the '81 behaved better than usual, especially in CP/M mode and with GEOS. Extra buffer RAM and a better DOS makes this drive harder to speed up.
Unlike other speed enhancements, Jiffy Dos is not through when your program is loaded. It is still active, and gives you added speed while working within your application. Saving and reading of data files in word processing and data base applications is one area where Jiffy Dos is a big improvement.
Hardware Supported
Jiffy-Dos is available for all for the C-64, SX-64, 64C, C-128, 128D, the various configurations of the 1541, 1571 and 1581.
Also supported are a number of third party "clone" drives, including: FSD 1 & 2, Excel 2001, Enhancer 2000, Amtech, Swan, Indus, Blue Chip 1541 & 1571 clones, and the older MSD SD-1 & SD-2. We tested Jiffy-Dos on the C-64, C-128, 1541, 1571, 1581, Excel-2001 (1571 compatible), Blue Chip (1571 compatible) and the MSD SD-2. Some of the drive ROMs behave slightly differently than the standard 1541 or 1571. For example, the Blue Chip 1571 compatible will not format a disk double-sided in 1541 mode when not connected to a computer without Jiffy-Dos. The 1571 and Excel drives would.
Do not expect any increased compatibility from a third party drive after installing Jiffy-Dos. If it won't run certain software now, Jiffy-Dos is not likely to help.
Another small problem is with the MSD SD-2. This dual drive, 1541 clone is very handy for copying non-protected disks using the DOS duplicate command. Jiffy Dos uses the "D" command for listing a program to screen without disturbing memory. This means that you still have to type "OPEN15,8,15" etc. to duplicate a disk, rather than use the DOS wedge built into Jiffy Dos.
Support
We both had a set of bad chips that were replaced in days. We were told that both sets had cold solder joints under the chips.. The new chips also had a higher version number. Telephone questions to Creative Micro Designs were handled
quickly and professionally. Calls to them are at the user's cost, but C.M.D. will return your call if they need to research an answer.
Conclusion
If you have a C-64, frequently switch to 64 mode from the 128, then Jiffy is a must! C-128 owners will squeeze a little more speed from the 1571 but will rejuvenate their older '41. Even using a 1541 for CP/M on the 128 is now almost acceptable.
Another advantage of Jiffy-Dos is its support of the various 1541 and 1571 clones. After using Jiffy DOS for a while you will start taking it for granted. The very fact that you don't really notice it means that its doing the job without fuss, while leaving your cartridge and user ports free.
