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#dolphindos

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Dirk Wouters

Neue Hauptplatine für das Commodore 1541-Diskettenlaufwerk, Teil II

Hier nun der versprochene 2. Teil über eine neue Systemplatine für das Floppy-Laufwerk VC1541 von Commodore. Ein komplettes Redesign und die Zusammenführung verschiedener Projekte zu einem neuen Controller…

#1541 #C128 #c64 #commodore #CPLD #Disk #DolphinDOS #Ersatz #Erweitert #Generation #GPIB #IEEE488 #Laufwerk #Mainboard #Neu #PCB #SpeedDOS #VC1541 #Weiter #Xilinx

dirkwouters.de/neue-hauptplati

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ytm

What a day!

In case tomorrow I get hit by a bus I have already published everything on GitHub. It was quite difficult to find both C128 and 1571 DolphinDOS firmware parts. Now there is one more place that preserves them together.

The README file will be gradually updated with proper links and pictures.

github.com/ytmytm/c128dcr-Dolp

GitHubGitHub - ytmytm/c128dcr-DolphinDOS3: DolphinDOS 3 board for (but not only) C128DCR internal 1571DolphinDOS 3 board for (but not only) C128DCR internal 1571 - ytmytm/c128dcr-DolphinDOS3
#commodore128#c128#dolphindos
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ytm

Great success - it works! The biggest surprise is that the file name of the only DolphinDOS 3 1571 drive ROM I found suggested it's for a standalone 1571. However after testing in VICE it worked in C128DCR. This finally confirms that indeed that ROM is good for 1571CR.
That is a bit strange because both original Commodore DOS ROMs as well as JiffyDOS images have different versions for standalone 1571 and 1571 from C128DCR.

On the computer side DolphinDOS 2 kernal works flawlessly with DD3 in the drive. (SilverDream! mentioned that he never had DD3 kernal rom). @X command (inherited by SD2IEC) shows current status: RAM expansion, fast loader, write verification, parallel connection are enabled. DOS extension works as well.
DolphinDOS 3 in C128 mode with 1571. It loads data faster than JiffyDOS but a bit slower than C64 more DD3. I think this is because the memory bank routing.
#commodore128#c128#dolphindos
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ytm

Parallel cable was the next step. The IDC connector end doesn't have strain relief because then I wouldn't be able to push it through user port opening while the mainboard is in.
The connector is easy to make, but with symmetrical plugs I'm never sure what am I looking at on the drawing. Photo for reference (also for me). Side with one wire is up, side with 9 wires with red on the left is bottom.

Populated and connected board. All ROMs are in. Later I changed the top/bottom 32K jumper into a wire to C128 Kernal switcher latch, so that JiffyDOS/DolphinDOS Kernal and 1571 DOS ROMs are switched simultaneously. The ribbon cable is routed to the back, under the power supply to go out of the user port and back into user port plug.
Commodore User Port parallel (burst) ribbon cable standard: red is the first wire, connected to the bottom row, to pin 'B' (/FLAG2), followed by 8 data lines. The 9th wire goes to the top row to pin '8' (/PC2).
#commodore128#c128#dolphindos
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ytm

6502 survived and the drive works: w/o 40pin ribbon!

Now I need a break. I have to prepare ROM images and a parallel cable to test if DD3 actually works.

The daugtherboard will have two switchable 32K ROMs: DD3 and JiffyDOS patched to use extra RAM as a track cache: github.com/ytmytm/1571-TrackCa

It's not as fast as DD3 but I will use JiffyDOS across other devices (SD2IEC/UII+).

I need to do the same for U32 Kernal ROM for both 128 and 64 modes too.

C128DCR mainboard with DolphinDOS 3 daughterboard plugged into U101 chip socket. CPU 6502 is raised to the daughterboard. No 40-pin ribbon necessary.
#commodore128#c128#dolphindos
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ytm

In the next step I had to desolder 6502 that controls the 1571 and replace it with a socket.
I added fresh solder from the bottom and then used desoldering tool to remove it. It's never enough to free all the chip's legs, so then I used hot air from the top side.
On the right a part of my earlier 1571CR RAM expansion is visible. This will be removed - DD3 board has the same function.

Here is the earlier project if you're interested: github.com/ytmytm/c128-bytewid

C128DCR mainboard with 6502 U101 removed.
#commodore128#c128#dolphindos
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