Search found 2297 matches

by Dave
Thu May 23, 2019 4:45 pm
Forum: Hardware
Topic: Asymmetric multiprocessing...
Replies: 42
Views: 1234

Re: Asymmetric multiprocessing...

The hardware for that would be comically simple. If you develop the calls/traps, the hardware will definitely be available for you to play on. More interestingly, it would be fairly easy to just have a DPRAM "bridge" card than could then accept one or multiple CPU cards. I have some 64Kx16...
by Dave
Thu May 23, 2019 3:13 am
Forum: Hardware
Topic: Asymmetric multiprocessing...
Replies: 42
Views: 1234

Re: Asymmetric multiprocessing...

I plan to discontinue the ROM port after Issue 8 as the image can be saved in flash and relocated. I found the connectors to be very difficult to source, and quite expensive at £5/00 a piece. Therefore, I will be offering it as a built time option - if you don't want it, your Issue 8 board will be ...
by Dave
Thu May 23, 2019 12:34 am
Forum: Wanted
Topic: Devpac QL
Replies: 17
Views: 5172

Re: Devpac QL

(01983) 861342 seems to be their number.

I can't call it from the US though - well not economically.
by Dave
Tue May 21, 2019 6:05 pm
Forum: Hardware
Topic: Asymmetric multiprocessing...
Replies: 42
Views: 1234

Re: Asymmetric multiprocessing...

But that can be better done with fast SERial 68681 (one of the reasons why I'm doing it); 31250 MIDI option with opto-isolators along with full SER. Take a look at the NXP SCC2691. It has an auto-repeater feature which make the in/thru/out implementation not require any extra repeater hardware. App...
by Dave
Tue May 21, 2019 5:09 pm
Forum: Hardware
Topic: Asymmetric multiprocessing...
Replies: 42
Views: 1234

Re: Asymmetric multiprocessing...

But that can be better done with fast SERial 68681 (one of the reasons why I'm doing it); 31250 MIDI option with opto-isolators along with full SER. You'd have to change the crystal to get the right baud rate out of the 68681, so you would need to use a separate 68681 for MIDI and for serial. If th...
by Dave
Tue May 21, 2019 12:04 am
Forum: General QL Chat
Topic: Internet and the QL
Replies: 38
Views: 1595

Re: Internet and the QL

But it does not contain the QL-side email client, which is where the procedures of communication with the server need to be handled, and where the ESP32 functions would need to be attached. The QL-side software for that does not automatically exist, just because there is a piece of ESP32 hardware. ...
by Dave
Mon May 20, 2019 2:34 pm
Forum: General QL Chat
Topic: Internet and the QL
Replies: 38
Views: 1595

Re: Internet and the QL

I wonder if a pragmatic approach, like finding or hosting classic email servers, could help without "outsourcing" encryption to a non-native CPU. (By the way, I'm not sure that an encryption engine outside the QL would automatically lead to the development of an email client which can han...
by Dave
Mon May 20, 2019 2:54 am
Forum: General QL Chat
Topic: Internet and the QL
Replies: 38
Views: 1595

Re: Internet and the QL

I find it exaggerated to say that TCP/IP is useless without encryption. It can still be used for LAN connections, internet connections from QL to QL, and many websites. From my experience with QLwIP I see the largest problem in the requirement of encryption for email server connections. (Which does...
by Dave
Sun May 19, 2019 8:30 pm
Forum: Hardware
Topic: Asymmetric multiprocessing...
Replies: 42
Views: 1234

Re: Asymmetric multiprocessing...

Derek_Stewart wrote:I have not checked them against the original, but they look about right.


So Dn -> ZAn and An -> ZDn? Why would they do that?
by Dave
Sun May 19, 2019 8:25 pm
Forum: Hardware
Topic: Asymmetric multiprocessing...
Replies: 42
Views: 1234

Re: Asymmetric multiprocessing...

....for a basic system you don’t need dual port RAM. One third party Z80 second processor system for the Acorn BBC B used two PIO chips back-back for processor to processor communications. In this case a 6522 VIA for the 6502 and a 8255A for the Z80A. Nothing *needs* dual port RAM. But: If I put a ...