YMODEM (fastest)

Although EazyLink2 offers more features and is more tolerant of varying serial port hardware configurations, YMODEM file transfers reach triple its maximum speed - achieving 3K/sec at 38400bps regardless of OZ version. This is because the YMODEM implementation does not use the OZ serial driver, so it is not limited to lower baud rates by the driver issues in the original Cambridge ROM versions. Also, by increasing the block size from 128 bytes to 1K and by batching multiple files together into a single session, YMODEM significantly increases communication efficiency.

Transferring the 256KB of OZ 4.7.1 ROM files will take around 1 min 25 secs - something that is an agonising order of magnitude slower on an unmodified Z88, constrained as it is to 9600bps in EazyLink2, or slower still if using ImpExport.

Z88 Setup

There are several ways to perform a YMODEM transfer on the Z88, which will depend on OZ version.

OZ Version	Popdown	Method

OZ Version	Popdown	Method
5.0	Filer	`TAB` to select multiple files, send batch using `◇` `S` `B`, receive a batch into the current directory using `◇` `R` `B`.
5.0	Shell	`sb -k filenames` to send, `rb -c` to receive.
4.5 - 4.7.1	ImpExport	`Y` for YMODEM, then `C` for CRC, then `K` for 1K block size. Wildcards are permitted for batch sending. `ESC` to exit.
2.2 - 4.4.1	XY-Modem	`Y` for YMODEM, then `C` for CRC, then `K` for 1K block size. Wildcards are permitted for batch sending. `SHIFT`+`ENTER` to exit.

Remember to set the serial transmit and receive baud rates to 38400 in Panel.

Computer Setup

On the computer side, the recommended software is WindTerm since it is free and is available for Windows, macOS, and Linux. Configure as follows:

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New Session, then pick the Serial tab at the top. Pick your serial device (it will be a COM port for Windows users). Leave "Data" set to binary.

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Choose Serial Protocol, then configure Baud Rate to 38400bps and Flow Control as RTS/CTS.

To minimise delays from handshake timeouts, the sending side should always be started before the receiving.