Using the QIMSI-QL Link

[janbredenbeek]

I'm surprised you can not see the same effect. Which hardware and OS are you using on the QL side?
In my case Issue 5 QL motherboard, Minerva ROM, QIMSI, SuperGoldCard running SMSQ/E.

Issue 6 QL, Minerva (but that's irrelevant since you have to run SMSQ/E for SERnet), QIMSI and (non-Super) GC.
Maybe the SGC's 68020 has some influence?

[janbredenbeek]

I'm surprised you can not see the same effect. Which hardware and OS are you using on the QL side?
In my case Issue 5 QL motherboard, Minerva ROM, QIMSI, SuperGoldCard running SMSQ/E.

Issue 6 QL, Minerva (but that's irrelevant since you have to run SMSQ/E for SERnet), QIMSI and (non-Super) GC.

I stand corrected, SERnet version 2.25 works with Minerva and my FIFO driver. The version that asked for SMSQ/E was 3.01, but I couldn't get that to work on QPC2 anyway.
I just tested with an Issue 5 QL which had problems receiving under Minerva, remote directories didn't get through and I even got an overrun (blinking LED) when trying to load a screen across the network. SMSQ/E appeared to work though.
Will do more testing tomorrow...

[Peter]

Here are updated MiniQ68 programs for SER-QL transfer at 115200 Baud (sources included) and 9600 Baud. This version adds an extra 24 KB of receive buffer. Like the previous version, the green QIMSI LED to blinks after a buffer overrun.

I also attach the latest version of Jan's QL side driver, supporting SER4, SRX4 and STX4 over the QIMSI-MiniQ68 link.

Both are for testing puposes only.

[afx]

Hello, some questions:
Could someone post a photo of what the serial output connection from QIMSI would look like?
What type of connector could be used on the QIMSI side?

Greetings!

PD:
Peter, Jan, ... thanks so much for that development. It is a very interesting complement to QIMSI.

[janbredenbeek]

Could someone post a photo of what the serial output connection from QIMSI would look like?
What type of connector could be used on the QIMSI side?

No photo here, but it's clearly identifyable in the QIMSI manual's photo.

The serial interface is on the right-hand side of the QIMSI board as seen on the component side with the QL connector under (see page 4 of the QIMSI manual). It is recommended to solder three header pins onto the connector pads, on which you can solder the serial cable to (of course, assumed you have sufficient soldering skills or leave it to someone who have them!). The pin layout is as follows:

- pin 1: Ground (closest to the QL connector, also marked with a square pad)
- pin 2: TX Data (output)
- pin 3: RX Data (input, farthest from the QL connector).

When connecting to the DB-9 RS-232 connector on a PC or Q68, the wiring should be as follows:

Code: Select all

| QIMSI | PC/Q68 |
|-------|--------|
|   1   |   5    |
|   2   |   2    |
|   3   |   3    |

NOTE: This assumes you have a straight-through cable between QIMSI and the other end. If you have a null-modem cable (used to connect two computers together), pins 2 and 3 will have to be reversed. If in doubt, please check the wiring using a multimeter. QIMSI's serial port has only minimal buffering so it's very likely that wrongly connecting pins 2 and 3 will fry your QIMSI, especially with PC ports which use 'real' RS-232 signal levels of +12 and -12 volts (unlike the Q68).

Peter, Jan, ... thanks so much for that development. It is a very interesting complement to QIMSI.

Thanks.

[Peter]

Peter, Jan, ... thanks so much for that development. It is a very interesting complement to QIMSI.

Thanks. Some time ago I also wrote a program to configure baudrate settings etc. from QL side, that I didn't release due to lack of time.
With sufficient interest, I'll look into it again.

The QIMSI serial port was mainly meant to debug/use the MiniQ68, to which it is directly connected.
Maybe I should have given it direct QL side connectivity. But I needed to release QIMSI at some point and finish the hardware.

[janbredenbeek]

I've created a new GitHub repository https://github.com/janbredenbeek/QIMSI-SER4 with the serial driver software I wrote so far. It's far from finished but should be usable for serial transfers between QL and Q68 or PC (for Q68, I recommend using SERNET v2.25 on both sides).

[afx]

Jan, Peter, thanks once again for the responses and support for this QIMSI feature.

QIMSI's serial port has only minimal buffering so it's very likely that wrongly connecting pins 2 and 3 will fry your QIMSI, especially with PC ports which use 'real' RS-232 signal levels of +12 and -12 volts (unlike the Q68).

From my ignorance, couldn't that have a solution with some "external protection"?

[Peter]

Jan, Peter, thanks once again for the responses and support for this QIMSI feature.

QIMSI's serial port has only minimal buffering so it's very likely that wrongly connecting pins 2 and 3 will fry your QIMSI, especially with PC ports which use 'real' RS-232 signal levels of +12 and -12 volts (unlike the Q68).

From my ignorance, couldn't that have a solution with some "external protection"?

The QIMSI SER input is well protected already.

A supressor diode could be added to also protect the output.
But then the supressor diode needs to be soldered correctly - it's easier to make a correct cable right away.
With correct cable, QIMSI is designed to survive if the 3 pin header is accidentally plugged in with wrong orientation.

In practice I see less risk than Jan. By experiment, the output appears pretty robust, although not specified.
The QL also had no short circuit protection specified, as far as I know.
SER without hardware handshake is only 3 wires to get right... should be doable.