[Coco] CoCo <--> Raspberry Pi
John E. Malmberg
wb8tyw at qsl.net
Mon Mar 16 09:36:56 EDT 2020
Thunderbird has decided that it will not show me Gene Heskett's reply to
On 3/9/2020 11:57 PM, James Ross wrote:
> Of interest as well was the CoCo <--> Raspberry Pi project discussed
> on the latest CoCoTalk – I caught a good 30 minutes of that
> conversation on the day. I went back and listened to that whole
> section, it starts around the 3 hr mark ...) Quite interesting,
> kudos to the dude that is experimenting w/ that.
Did not know about that. I am several thousand messages behind on this
forum, and having to switch to gmain.io reset all messages to be unread.
> I wonder how fast you can feed data to the CoCo through the keyboard
> input, if bypassing the ROM and talking directly to the port in
You mean by a 6809/6309 program that is polling the ports and with a
computer attached instead of a ke? I would have to look at the I/O
timing for the chipset, but you can probably transfer at about 1/10 of
clock speed depending on efficiently that you wrote the code.
> I imagine the Raspberry Pi (possibly only the newer ones 3, 4?) are
> fast enough to R/W directly to cartridge slot at full double speed
> 1.79MHz? ...
I do not think that is the best connection method. There is not enough
I/O pins so that extra selection logic is needed.
And most of the IO expanders that I have found for the Pi are also too slow.
I am currently looking at a https://www.sparkfun.com/products/9713 as
something to connect to the 40 pin and other I/O ports, or just to
emulate a COCO altogether.
That device has enough I/O to connect in, and it can connect to the Pi
via either SIO or USB.
I am not sure about any buffering / level conversion. What I like about
that device is it is breadboard ready to go.
I am only just now starting to go through my COCO stuff to figure out
what I have that is still functional and what can be repaired.
More information about the Coco