After July’s spurt of activity, the PCBs and parts arrived in the mail. It’s not central to the design, but if it works then the card could function as an all-in-one virtual disk like the CFFA3000, in addition to functioning as a disk controller for external drives. 2 MB is enough to store 14 disk images of 5.25 inch disks, or a single larger disk image.
#Disk aid 2017 serial
Just for grins I added a 2 MB serial EEPROM to the board, which you can see at U2. Even with these small components, I was still able to solder the entire prototype board myself by hand. It’s barely any bigger than a 0805 size SMD capacitor. There’s a tiny 3.3V voltage regular on the board, which you can see at the lower-right at U3. One of the chips operates bidirectionally on the data bus, and the others handle the unidirectional address bus and control signals. These chips operate at 3.3V but are fully 5V tolerant, and the Apple II happily accepts their 3.3V output as a valid logic “high”. I used four 74LVC245 chips as bus drivers. For other external disk drives, I built a small adapter that converts a short length of 20-pin ribbon cable to a DB-19 female connector.īecause the FPGA’s maximum supported I/O voltage is 3.3V, but the Apple II has a 5V bus, some level conversion is needed. In fact for the Floppy Emu, you can connect a 20-pin ribbon cable directly from the Emu to the FPGA card, with no DB-19 required. The external disk is connected to the card with a standard 20-pin ribbon cable, just like what you’d find inside an Apple IIc, or on the Floppy Emu. The FPGA can be programmed through a JTAG header on the card. Unlike some FPGAs, the MachXO2 family also has built-in flash memory to store the FPGA configuration, so it doesn’t need to be reloaded from an external source at power-up. It also has some nice features like a built-in PLL oscillator and integrated programmable pull-up and pull-down resistors. This 100-pin bad boy has 1280 LUTs for implementing logic, and 8 KB of embedded block RAM to serve as the boot ROM or for other functions. The core of the prototype board is a Lattice MachXO2 FPGA, specifically the LCMXO2-1200HC. I worked like mad to finish the design in late July, just before a trip to Yellowstone National Park, which gave this project its codename. I realized the design wasn’t limited to being a Liron clone, but could also probably be a Disk 5.25 or Disk 3.5 controller with just a change of firmware. The entire design boiled down to some 3.3V level converters and a single FPGA, with a bunch of connectors and passive components. By selecting a moderately roomy FPGA, I was able to incorporate the boot ROM functionality too, so no actual ROM chips are needed. Creating a Verilog reimplementation of the IWM was harder, but with the aid of the IWM spec and a logic analyzer I got it done.
#Disk aid 2017 code
Writing Verilog code for the FPGA to duplicate the 7400 chips’ functions was easy. It’s a single IWM (the famous Integrated Wozniak Machine), combined with a small number of standard 7400-series logic chips, and a ROM to hold the boot code. Mapping out the complete schematic of the Liron took a couple of days. People started asking about the possibility of a Liron clone card, so I went to work. But only Liron card owners could benefit, and the Liron card is fairly obscure and difficult to find. For the first time, it was now possible to emulate a 32 MB Smartport disk on an Apple II, II+, or IIe with the Floppy Emu. Back in July there was a surge of interest in the Liron disk controller, when I updated the Floppy Emu firmware to add Liron support. This project has been nearly finished since August, but I’d hoped to delay announcing it until it was 100% done. This hypothetical universal controller card could connect to almost any Apple II disk drive, or a Floppy Emu. Can an FPGA-based solution save the day for retro collectors? You bet! Nearly all the existing disk controllers connect the same 8-bit bus to the same 19-pin disk interface, so a universal clone is merely a question of replacing the vintage 80s guts of the card with a modern reprogrammable FPGA.
#Disk aid 2017 mods
Kay Koba, Kero's Mac Mods Store on Mac ROM-inator I KitĪpple II disk controller cards are weird, there are a crazy number of different types, and many are rare and expensive.Hubert on Apple SmartPort Pin Directions.STEVE BURKE on Floppy Emu Disk Emulator for Apple II, Macintosh, and Lisa.
#Disk aid 2017 update
groinksan on Yellowstone Future Forecast Update.Steve on Floppy Emu Disk Emulator for Apple II, Macintosh, and Lisa.Yellowstone Universal Disk Controller for Apple II Floppy Emu Disk Emulator for vintage Apple II, Macintosh, and Lisa