QL IO board?

[Derek_Stewart]

[Sadly, I haven't got the board nowadays, and I can't remember who bought it off me. Otherwise I'd ask them to try to take good quality photos of the circuit board to see if it could be reverse-engineered.

Pity, as the QL World articles imply the idea to interface BBC MIcro interfaces via QontrolII

I doubt the ROM software would be accessible.

Maybe a 6522 VIA could be interfaced on the Q68 I/O port.

At the time, I had a BBC Micro (used to work for the BBC in those days, we used them to some extent at work).

I did do a few simple hardware projects, one example was a grid of multiplexed LEDs working as a "disco" light running lightshow. I had it working from both BBC micro and QL (can't remember if it was the same interface to both machines or not), also a Spectrum, but the Spectrum one was different to the other two, just a project I copied from a magazine and built on veroboard - I remember struggling to make that one work, it took me several days to spot my soldering mistake. I never took it further than a matrix of LEDs on a veroboard before the novelty wore off and I diverged into more serious software projects once my employer got me writing some early office software on BBC micro.

I also connected a few devices to a QL via serial ports - I think I got the circuit diagram for that interface from Elektor or possibly one of the other electronics mags around in those days. The beauty of connecting via serial ports was that although slow, it was easy to program.

There's also the Minerva I2C interfaces for anyone able to get hold of those nowadays.

The Q68 I2C interface can do the same function as the Minerva MkII I2C, except the interfaces can be bought cheaply, I tried to the Sparkfun QWICC interface which is a 2mm JST connector. I will make some experiments, given time.

[Pepperm]

There was this:
IIO-card.jpg

Probably easiest to go with Minerva mkII and I2C (or Q68).

Where can I find out info and construction de tails for the Minerva mkII and I2C please? I have the Minerva ROM with TK2 fitted and have seen mention of the hardware but can’t find any actual details of what it is and how I can make it.

[dilwyn]

There was this:
IIO-card.jpg

Probably easiest to go with Minerva mkII and I2C (or Q68).

Where can I find out info and construction de tails for the Minerva mkII and I2C please? I have the Minerva ROM with TK2 fitted and have seen mention of the hardware but can’t find any actual details of what it is and how I can make it.

A little bit of info here https://qlwiki.qlforum.co.uk/doku.php?i ... va&s[]=i2c and here http://tfs.firshman.co.uk/ql/minerva.htm

Manuals at https://dilwyn.qlforum.co.uk/docs/manua ... tfservices

They were produced by TF Services, but have sadly been out of production for some time. You might get lucky and find second hand ones on eBay or SellMyRetro.com. I'm afraid I have no idea whether the standard Mk One Minerva board can be upgraded to add the I2C parts to make it into a Mk Two board.

[ones' complement]

Earlier thread on mkII here : https://www.qlforum.co.uk/viewtopic.php?t=1993
(details from here on : https://www.qlforum.co.uk/viewtopic.php?p=43595#p43595)

[Derek_Stewart]

Earlier thread on mkII here : https://www.qlforum.co.uk/viewtopic.php?t=1993
(details from here on : https://www.qlforum.co.uk/viewtopic.php?p=43595#p43595)

Ahh... an another little job I forgot about.

I have to repair the Minerva MKII and I have another one that has a fault.

Probably need a Schematic drawing and generate a PCB for the new Minerva MKII, meanwell I have to use the Q68 for I2C

[XorA]

Earlier thread on mkII here : https://www.qlforum.co.uk/viewtopic.php?t=1993
(details from here on : https://www.qlforum.co.uk/viewtopic.php?p=43595#p43595)

Ahh... an another little job I forgot about.

I have to repair the Minerva MKII and I have another one that has a fault.

Probably need a Schematic drawing and generate a PCB for the new Minerva MKII, meanwell I have to use the Q68 for I2C

Do you have the Minverva MKII PAL/GAL equations? I think thats where Dave's clone fell down!

[Pr0f]

I thought most of the clever stuff was done in the code itself - the bit banging of CLK and DATA lines - and there is some sort of status engine there too - so I suspect the GAL was just there to provide some additional decoding for the IO addresses used for the I2C interface itself and the EPROM decode for the 64K eprom on the MKII so it behaves like a 48K ROM

[Pr0f]

I believe it hi jacks one or two I/O addresses in the 48K lower ROM space.

In fact it looks like it has 4 addresses - and the GAL may be working in registered mode and setup as flip flops to be toggled on accesses to the addresses - after having a quick and dirty scan at the code.

* a2-a5 these are set here to the four byte addresses of the interface.


lea $bfdc,a4
lea 1(a4),a5
lea 2(a4),a2
lea 3(a4),a3

[Derek_Stewart]

Hi,

I have 2 GALs, if there is no protection, I shoukd be able to disassemble the JEDEC code.

[martyn_hill]

Hi everyone!

I did some work to try to understand the Mk2 Minnie GAL equations some time ago and, based on TF's JED map file (MGCV1.00), decompiled using JED2EQN and it tidied-up a bit.

I attach it here - modified a tinsy bit to allow a switch to be fitted to enable/disable the upper 16KB ROM decode, depending on whether you have TK2 or something else (QL-SD?) already mapped-in there.

The clever stuff falls between the bit-banging in the Minerva code and the 'state-machine' encoded in the GAL.