On 29/08/2021 14:19, Peter Maydell wrote:
> On Sun, 29 Aug 2021 at 11:05, Mark Cave-Ayland
> <mark.cave-ayland@ilande.co.uk> wrote:
>>
>> Here is another small set of ESCC fixes from my attempts to boot MacOS on the q800
>> machine.
>>
>> When MacOS loads the OpenTransport extension on boot it attempts to enable
>> SDLC mode on the ESCC. QEMU's emulation doesn't support SDLC mode, but without
>> these fixes the active low STATUS_SYNC bit in R_STATUS is continually
>> asserted causing the extension to hang on startup as it believe it is constantly
>> receiving LocalTalk responses during its initial negotiation phase.
>
> The ESCC data sheet is the first one I've ever encountered that includes
> a multiple-choice test on features of the device ("ESCC Questions and Answers"
> on pages 385/386: http://www.zilog.com/docs/serial/scc_escc_um.pdf ) :-)
I wonder why the idea never took hold? :D
ATB,
Mark.