On 4/25/20 10:25 PM, Stephen Adolph wrote:
Still playing around with the BCR TTL serial port.
...yes it has it's limitations... half duplex, no flow control, bit-banged
..but it is fast! Today I was able to get 32kB transferred in 7
seconds. That's pretty close to 100% utilization on the 57600 baud line.
I think that is a new M100 record. It might need independent verification!
(why? to reduce time for CP/M disk backups. 4MB will take a 1/2 hour
with this approach, or more than an hour at 19200 baud.)
Thinking high level, ignoring for the moment that you've already gone a
long way down a certain road and the work is done etc...
By the time you have to go that far, to get only that far, why keep
bothering with the bcr port instead of just using the system bus?
1/2 hour is still too long.
You've got a custom pcbs filling both the optrom and system bus sockets
already anyway, and both sockets are on the bus, so you might as well
use the system bus pcb for a better uart or off the shelf module, and a
connector.
Or make the 4MB removable via microsd instead of soldered on flash?
Again if there is no room for that on the optrom pcb, couldn't that go
on the system bus pcb? The two should be able to talk to each other
through the bus itself, since they're both on it.
They make very small already self-contained arduino microcontrollers
coupled with an sd card slot, where you could talk to it directly via
ttl or i2c or SPI on just a few wires totally aside from the bus and it
all would fit in the optrom compartment.
https://www.amazon.com/dp/B07XDTGPCX
I have a couple of those and took a couple pics to show where it could
fit in the cavity. If it was simply double-side taped or glued right to
the back of the system bus pcb, it might might just fit under the stock
door cover if the system bus pcb sits very close to the socket, or, even
if it's too tall, it definitely fits next to the optorm socket.
https://photos.app.goo.gl/3sMyAkeebKYJALwz5
Actually now that I think about it, you could leave the existing 4MB
flash as it is and just add the openlog as the backup/restore
destination instead of another host. It's the same serial connection
you're already set up to use. They already have firmware that does
nothing but the job of storing and retrieving from serial to sdcard.
https://learn.sparkfun.com/tutorials/openlog-hookup-guide/all
--
bkw
