On Friday, February 26, 2016 at 11:49:15 PM UTC+11, Bruce Mardle wrote:
> On Thursday, 25 February 2016 21:15:39 UTC, Ola wrote:
> > Hi,
> > I recently got a 68008 working (i.e. loading scode) with 3 ttl chips, rom,
> > ram (512+128K) and 68681. But I have to admit - I used a pcb (10*10cm).
> > Amazing how many errors you can do in a project - even after you are sure it
> > MUST be correct.
> > But very rewarding to succeed!
> I've been designing a board with a XR82C684 UART for, erm, longer than I care to think about! It claims to be 68000-compatible, though it still expects ME to turn its ~INT signal into ~IPL2/1/0 and generate an interrupt acknowledge [scowl].
They never "just plugged together". Something had to handle the IPL pins. Although I remember you could simply decode the space pins to get an IACK and connect that directly to VPA to get one of 8 Autovectors. I've also seem cheap hardware (looking at YOU, Apple) that had only three interrupting devices and hardwired the requests to IPL0, 1 and 2. So the only valid interrupts were 1, 2 and 4, but you could get the other vectors if more than one device interrupted at once. You could even get an IPL7 if you were unlucky. Better to use a priority encoder chip.
> I see from a Google search that Freescale (née Motorola Semiconductor) issues an End Of Life notice on the 68681 in 2009... but the NXP version seems readily available.
Distributors may have stock but that part is certainly EOL'd:
The above doesn't show the status, but if you then type "scc68681" into the Search Field you'll get a page listing four of them, all "End of Life".