Skip to content

V4 Setup

Keir Fraser edited this page Oct 5, 2023 · 3 revisions

This page describes hardware setup of the Greaseweazle V4. You should also read the Software Installation page to set up the control software on your host PC, and peruse the Usage pages listed in the wiki sidebar.

To set up your V4 board you will need the following additional items:

See the following advanced notes on setup:

Floppy drive

You can connect your V4 to any floppy drive implementing a Shugart interface: Old PC 3.5-inch and 5.25-inch drives are a good choice, or an Amstrad 3-inch drive for Amstrad CPC and Spectrum +3 disks. Note that the drive need not be the exact same model as in the system to which the disks belong: a PC 3.5-inch drive can read and write Amiga and ST disks, for example.

An 8-inch drive can be connected via a suitable interface board such as FDADAP.

Floppy data cable

Your drive connects to Greaseweazle using a standard 34-pin ribbon cable. If your cable will not plug into the V4, note that some cables have a blocked pin at each end: pin 5 at the Greaseweazle, and pin 3 at the drive connector. You can fix this by drilling out the cable's blocked pin 5, or by carefully cutting and removing pin 5 from the Greaseweazle connector, or by rooting around for a 34-pin cable without blocked pins.

By default the V4 boards acts like an IBM-PC controller addressing Drive A: This assumes a PC floppy drive and a ribbon cable with a 'twist' on pins 10-16.

A common alternative setup is a PC drive with straight ribbon cable. In this case you must select drive B (--drive=b)

Another common setup is an Amiga, Atari ST, or other vintage drive which responds to drive-select DS0 (pin 10). In this case you must use a straight cable and select drive 0 (--drive=0).

For further info please see the documentation for Drive Select.

Floppy power

3.5-inch drives typically require only 5v power and can usually be supplied directly from the power header on the Greaseweazle board. Older 5.25- and 3-inch drives typically are more power hungry and require 12v power too: These you must connect to a separate power source.

If you have problems accessing your drive and you believe your Greaseweazle is correctly set up, it can be because the drive requires more power than it can obtain via USB. In this case try connecting your drive to its own power supply.

For a suitable drive power supply for 3.5- and 5.25-inch drives, search for "Molex power supply". These usually feature 5V and 12V supply at 2A, and a full-size Molex power connector; They connect directly to a 5.25" drive, or to a 3.5" drive via a Molex-to-floppy adapter cable.

USB cable

V4 requires a USB-A to -B cable (commonly known as a "USB printer cable") to connect to your host PC (Linux, Mac, Windows, etc). Greaseweazle appears as a serial or modem device, depending on your OS.

Jumper configuration

Greaseweazle V4 has a 6x2 jumper block through which a number of features can be accessed:

WRT.ENA: From factory these pins are jumpered to allow your Greaseweazle to write to disk. Remove this jumper to physically disable write support and provide an extra layer of safety when preserving precious vintage media.

Firmware Update Mode: Your V4 will automatically enter firmware-update mode when requested. However this mode can also be manually forced by placing a jumper across the TXO-RXI pins.

Drive terminations

The standard floppy bus is open collector with termination (pull-up resistors) at the far receiving end.

The terminations on older 5.25- and 8-inch drives can be as strong as 150 ohms. It is also important that only one drive in a bussed setup has 150-ohm terminations: Greaseweazle V4 cannot drive into multiple strong pull-ups in parallel.

The strong termination in older drives is usually optional because only the last drive on a ribbon cable is expected to terminate. The terminating resistors on intermediate drives are traditionally either disabled by a jumper, or removed entirely. This correctly terminates the signal lines and also prevents overloading the drive controller's outputs with excessive pull-up current. However, if termination is missing entirely then the drive input signals will float (usually at around 2 volts) with unpredictable results!

  1. If using 3.5-inch and 3-inch drives, this is not a concern. Their terminations are weaker and cannot be disabled.
  2. If using a 5.25- or 8-inch drive on its own, make sure that the termination resistors are present and enabled.
  3. If using a 5.25- or 8-inch drive in a multi-drive setup, you probably do not need the termination resistors.

Note that an unterminated setup will work with other flux boards such as Kryoflux and Supercard Pro, which actively drive their outputs both high and low. Greaseweazle by contrast has standard open-collector outputs which rely on termination resistors to pull signals high.

External LEDs

If casing your V4, you may want to use external LEDs in place of the on-board ones. This can be achieved as follows:

  • Power LED: Connect +ve lead to jumper pin 5V via a suitable resistor. Connect -ve lead to any jumper pin marked GND.
  • Activity LED: Connect +ve lead to jumper pin 5V via a suitable resistor. Connect -ve lead to jumper pin TXO.