The Spectrum, running program 'IPC' acts as a file server or
'Intelligent tape deck' to transfer SKYWAY FORTH screen blocks to the ZX81.
Both the rack mounted ZX81 and the consol may utilise the file server. This system
uses two way communication, one system requests a specific Forth block and the Spectrum
running IPC reads from the floppy and sends it to the Forth system.
As the disk interface supports memory image dumping and restoring it was possible
to preload a number of blocks into memory in the manner of a cache at the same time the
program (IPC) was loaded.
It is perhaps a good place to mention that the common communications protocol
for transfering programs from one system to another (not the ETI SBC which is
rack mounted) is the SKYWAY FORTH tape format.
The consol version ZX81 sends and receives signals
that are at the original ZX81 specification (mV audio level) using the rear DIN socket for
tape storage. Other systems use TTL logic level signals, as does the ZX81 consol using
port 2 output on the front panel. The block diagram shows the connectivity,
for specific instructions as to how a particular function is performed or
how a particular program is run the respective section should be consulted.
This information is usually in a read.me file, not yet on the website.
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