The Sinclair QL Forum

XorA wrote:

Silvester wrote: Indeed, but it is at least reliable. I always thought QL IPC serial was dodgy, but I've yet to get a USB serial adaptor to work on a laptop above 9600 reliably (CH340 or PL2303).

..ooOO

I have about a billion of those things due to my job, never had a problem with them.

Works OK at 5V TTL levels over short distance, but fails when through 1488/1489 RS232 level shifters at 38400 over a couple of metres.

Works OK at 5V TTL levels over short distance, but fails when through 1488/1489 RS232 level shifters at 38400 over a couple of metres.

Thats because you need rs-485 at those distances.

XorA wrote:

Works OK at 5V TTL levels over short distance, but fails when through 1488/1489 RS232 level shifters at 38400 over a couple of metres.

Thats because you need rs-485 at those distances.

Using QXL or Q40 with 16650 UART RS232 levels at 38400 to MIDI works OK. Also using QPC1/2 emulators on PC with 16650 works.

Just cannot get a USB serial adaptor to work at those speeds, even just trying Minicom on Lubuntu fails.

I also have a Yamaha CBX-T3 which can convert 38400 to MIDI 31250. It has RS485 interface which will also works as RS232, though even trying a RS485 link failed.

I did notice the laptop PSU (switched mode) does cause a lot of noise on USB ground. But problem still occurs when running off battery.

Pity, I wrote a voice editor/filer for Yamaha SY35 using EasyPtr which would have been nice to use on laptop with emulator.

(The less said about the CH345 USB MIDI interface the better It can't do SYSX dumps!)

XorA wrote:

Silvester wrote: Indeed, but it is at least reliable. I always thought QL IPC serial was dodgy, but I've yet to get a USB serial adaptor to work on a laptop above 9600 reliably (CH340 or PL2303).

..ooOO

I have about a billion of those things due to my job, never had a problem with them.

Solution was to use tiny MAX3232 powered from same USB port (attempts with external MC1488/1489 circuit failed):

http://www.ebay.co.uk/itm/5PCS-Mini-RS2 ... SwdzVXiFJm

Is there a UK version of this board yet. Would be willing to test/help convert if needed.

Cheers,

Andy.