VDU 2 and 3 are supported to enable and disable “printer”, which for our purposes on Agon is the debug serial terminal
VDU 1 will send next character to printer only
VDU 21 will disable the VDU command processor, allowing only output to “printer” - only VDU 1 and 6 commands will be processed
VDU 6 re-enables the command processor
VDU 20 (reset palette) added for good measure, as it was missing
various extra control keys are now supported on the VDP (ctrl B, C, F, G, L, N and O) and work as on Acorn systems (mirroring VDU 2, VDU 3, VDU 6 etc). ctrl-P is also supported, but toggles printer rather than performing a CLG, matching RTRussell’s BASIC
NB the processing of VDU 21 / VDU 6 currently differs from Acorn systems. On an Acorn system, after performing a VDU 21, subsequent VDU commands will still be attempted to be received in their entirety, but just would not be executed. So, for instance, performing a VDU 22, 6 would be ignored on an Acorn system, as the VDU 22 command (change mode) is expecting a byte. On an Agon system with these changes the VDU 22 byte alone would be ignored, and the 6 would be interpreted as a plain VDU 6.
VDU 2 and 3 are supported to enable and disable “printer”, which for our purposes on Agon is the debug serial terminal
VDU 1 will send next character to printer only
VDU 21 will disable the VDU command processor, allowing only output to “printer” - only VDU 1 and 6 commands will be processed
VDU 6 re-enables the command processor
VDU 20 (reset palette) added for good measure, as it was missing
various extra control keys are now supported on the VDP (ctrl B, C, F, G, L, N and O) and work as on Acorn systems (mirroring VDU 2, VDU 3, VDU 6 etc). ctrl-P is also supported, but toggles printer rather than performing a CLG, matching RTRussell’s BASIC
NB the processing of VDU 21 / VDU 6 currently differs from Acorn systems. On an Acorn system, after performing a VDU 21, subsequent VDU commands will still be attempted to be received in their entirety, but just would not be executed. So, for instance, performing a
VDU 22, 6would be ignored on an Acorn system, as the VDU 22 command (change mode) is expecting a byte. On an Agon system with these changes theVDU 22byte alone would be ignored, and the6would be interpreted as a plainVDU 6.