New Raspberry Pi to 1MHz bus interface

[mph1708]

I have switching between a "hardware" BeebSCSI system and an "emulated" BeebSCSI system, the only problem being that I only have space on my desk for one at a time.

So, starting with a suitably setup SD card with 4 jukebox partitions (0,1,2 & 3)

If on the hardware BeebSCSI system I select *SCSIJUKE 3, the change can be verified with *SCSISTATUS

On the "hardware" BeebSCSI system The Current jukebox number of 003 is a persistant setting.
And is NOT changed by Break, Shift Break or CTRL Break.

On the "emulated" BeebSCSI system The Current jukebox number of 003 is NOT a persistant setting.
And IS changed by Break, Shift Break or CTRL Break.
The upshot of this is that Break key (or Break key combination) resets the jukebox number to 000 taking you out of the selected partition / LUN.

I initially thought that the Jukebox had not been implemented in the emulated BeebSCSI because I tend to press CTRL Break after issueing the *SCSIJUKE command, so every time I looked the jukebox number was 000, it was only when I looked at everything step by step that I saw that the jukebox number was being changed as required, but was subsequently being reset.

[dp11]

Thanks for the extra info. That should be fixable.

[tone76]

***POSTING ON THIS THREAD SINCE THE FOR SALE THREAD IS CURRENTLY LOCKED FOR POSTING***

For those on the wait list in my For Sale thread, manufacturing of the next batch of 1MHz level shifters is now complete and awaiting courier pick up from the factory. It's taken a lot longer than the original quoted duration when I placed the order. I guess they're still catching up from the backlog when the factories were all closed down. Hopefully some of the extra time has gone on more stringent QA checking of the SMD component placement! I expect it to be at least a couple of weeks before these new boards arrive in the UK, but that may yet be impacted by the ongoing lockdown in the UK.

Thanks for the heads up. I was worried I may have missed my slot in the queue, as I've not had as much access to my laptop recently as I'd like (I've had to share it with my wife, as my laptop will connect to her work VPN and hers won't, apparently).

[tricky]

My boards just arrived, with four side of A4 instructions and pictures, good job.

[KenLowe]

Thanks for the heads up. I was worried I may have missed my slot in the queue, as I've not had as much access to my laptop recently as I'd like (I've had to share it with my wife, as my laptop will connect to her work VPN and hers won't, apparently).

You're actually top of the wait list now, but I can't update the wait list table whilst the For Sale forum is locked. For those further down the list, don't worry. I have more than enough boards on order to cover all remaining notes of interest, and also some extras to hold in stock.

My boards just arrived, with four side of A4 instructions and pictures, good job.

Wow. That took some time. I've just checked my records and note that your boards were posted first class on the 19th March!

[KenLowe]

Separately, I've also sourced a special 26 pin socket that allows the level shifter board to be close coupled to RPi, whilst avoiding the need to remove the yellow video socket on the RPi. I know this is probably not for you, but for others that would like to use their old RPi model B externally then this might be a good solution.

The special 26 pin headers arrived today, so I've soldered one onto a spare tube level shifter board. I also soldered on a right angle 40 pin tube header for remote install, but could equally have installed a right angle socket for underside install. Note that I've soldered the serial debug and power headers on the opposite side of the board to avoid any clashes with yellow vidoe socket on the RPi Model B. Once again I had to remove bridges from one of the JLCPCB factory installed resistor networks on the level shifter board to get it working .

Tested and working fine with RPi Model B (26 pin), RPi 3B, RPi 4B, RPi Zero & RPi ZeroW. It's a perfect fit for the RPi Model B, with no need to remove any components from the RPi or install any header extenders. I've got a small quantity of these 26 pin headers, so please let me know if you would a tube level shifters with one of these headers. There would be an incremental £2.50 charge for this special header:

[dp11]

I've just uploaded the latest version of the code to Github. This fixes the SCSIJUKE issue and reduce the M5000 CPU load.

[mph1708]

Thanks for fixing the *scsijuke issue
I switched over to the revised version earlier, and jukebox function now works as expected.
I don't use the M5000 package enough to say if there are any noticable changes.

Has anyone else experimented with the Ramdisc options ?
The Datacentre RAMFS seems to work OK giving the 4 virtual DFS drives, and the RCOPY utility is useful.
(The :4 NVRAM drive and :5 USB drive are something other than plain Ramdisc - so don't work)

The "Sprow" Ramfs works, but I am unclear as to the best way to use the 8M of space.
Are there any utilities available to harness this workspace ?

I also came across the Morley Ramdisc, but the ROM seems to stay in a switched off state if loaded up.
This system seems to adopt a different addressing scheme IIRC.

[dp11]

I had a look at supporting the Morley RAM disk. It doesn't appear to be compatible with other things and the documentation on exactly how the hardware works appears to be incomplete. I disassembled the ROM to try and learn more.

As you can preload the RAM from a file I was wondering if something like bad apple can be ported as you have 480Mbytes of ram to play with.

[KenLowe]

I've just uploaded the latest version of the code to Github. This fixes the SCSIJUKE issue and reduce the M5000 CPU load.

Confirming that the SCSI Jukebox function is working well for me too. It might just be my imagination, but the M5000 audio quality through the headphones on my Pi 3B is superb, and seems even better than before.

[dp11]

Yes , I thought It had got better too this morning, not exactly sure why. It might be down to the M3000 now defaults to disabled.

[KenLowe]

It might be down to the M3000 now defaults to disabled.

This got me thinking. Is it possible to disable other pieces of hardware? Specifically, I'm thinking about being able to disable the emulated SCSI drive, whilst retaining the other emulated hardware. For me, this would allow me to daisy chain in my physical external HDD whilst keeping the other emulated hardware. Other permutations may be of interest to others. TIA.

[dp11]

It is on my list of things to do. Are you thinking run time disable ?

[KenLowe]

It is on my list of things to do. Are you thinking run time disable ?

Nah. Nothing that complicated. Just via the config.

[KenLowe]

Just a quick update on this thread, since the For Sale thread is still locked. The next batch of 1MHz boards are in the UK and tracking tells me that they're heading to my local Post Office sorting office. I'm guessing there won't be any deliveries tomorrow, but perhaps Tuesday. I'll hopefully be in a position to start offering these boards to those on the wait list shortly, so if you're on the wait list, please expect a PM in the coming days .

[tone76]

Just a quick update on this thread, since the For Sale thread is still locked. The next batch of 1MHz boards are in the UK and tracking tells me that they're heading to my local Post Office sorting office. I'm guessing there won't be any deliveries tomorrow, but perhaps Tuesday. I'll hopefully be in a position to start offering these boards to those on the wait list shortly, so if you're on the wait list, please expect a PM in the coming days .

Cheers, Ken! Looks like I'll need to order myself a couple of Pi Zeroes.

[KenLowe]

Cheers, Ken! Looks like I'll need to order myself a couple of Pi Zeroes.

Please be aware that they're actually quite difficult to get hold of. Any time they are in stock, orders are usually limited to one unit; although you can normally by one Pi Zero and one Pi ZeroW (assuming they're both in stock at the same time).

[tone76]

Cheers, Ken! Looks like I'll need to order myself a couple of Pi Zeroes.

Please be aware that they're actually quite difficult to get hold of. Any time they are in stock, orders are usually limited to one unit; although you can normally by one Pi Zero and one Pi ZeroW (assuming they're both in stock at the same time).

I'm not necessarily going to order two at once. I was also thinking of ordering a Pi ZeroW in the faint hope that one day there might be someone much cleverer than I who can work out how to make the Pi ZeroW's wifi work with a Beeb.

[Rod C]

I'm not necessarily going to order two at once.

Hi tone76, I ordered two from Core Electronics in Australia by getting one of the special offer plus one from the bulk option as below. Their email notification was fantastic to tell me when they came into stock. Hope I ordered the right header. I haven't seen my interfaces yet as overseas mail is backed up. Maybe soon?

[KenLowe]

I'm not necessarily going to order two at once.

I haven't seen my interfaces yet as overseas mail is backed up. Maybe soon?

That's taking an awful long time. That's almost a month now . Royal Mail claim 6 - 7 working days for International Delivery, so I'm assuming it's got caught up with Covid lock downs. Hopefully any day now.

Anyone else still waiting???

[stuslayer]

Pimoroni have Pi Zero's in stock. No W's though

[tone76]

I'm not necessarily going to order two at once.

Hi tone76, I ordered two from Core Electronics in Australia by getting one of the special offer plus one from the bulk option as below. Their email notification was fantastic to tell me when they came into stock. Hope I ordered the right header. I haven't seen my interfaces yet as overseas mail is backed up. Maybe soon?
Core Electronics Order.JPG

I've used Core Electronics in the past, and am planning on using them to buy my next Pi or three. I know it can take a bit of time for them to get stock in from OS, but when they do they usually ship it out pretty quickly.

[KenLowe]

Some new 1MHz level shifter boards looking for a new home :

1MHz Underside Level Shifters

Factory build quality of this batch is much better. Of the 20 I've tested so far, I've only had to fix one board that had a couple of solder bridges. All the others have been spot on.

[Simon]

When this madness is over I could provide a loving home for one of these

[KenLowe]

Hi folks,

In order to simplify things a bit, I have been toying with the idea of only offering the underside option for the 1MHz and Tube level shifters, but then offering an additional adaptor board for those people who would like to use the level shifters remotely. The adaptor boards would look something like this. Ignore the fact the adaptor board has the wrong number of pins soldered on. This is just a mock up, to test that it all fits in the case:

1MHz bus adaptor plate

Attached to a RPI 3B and fitted in a case

Case all closed up

Adaptor plate installed, but ribbon cable removed

View from other side of case

Thoughts, please?

[hoglet]

Thoughts, please?

Don't you just need a cable with a female connector on one end and a cable-mounted male connector the other?

Here's an example of the male connector, which is the more unusual of the two.
https://uk.rs-online.com/web/p/idc-connectors/6741224

I used one of these regularly.

Dave

[egel]

Thoughts, please?

Don't you just need a cable with a female connector on one end and a cable-mounted male connector the other?

Here's an example of the male connector, which is the more unusual of the two.
https://uk.rs-online.com/web/p/idc-connectors/6741224

I used one of these regularly.

Dave

Like this:

Looks like not extremely much more expensive, only slightly more difficult to find.

[BigEd]

I have a tube-extender cable from the matchbox copro adventure: I seem to remember there was a hazard of some sort with using the wrong thing and letting the smoke out?

[KenLowe]

Don't you just need a cable with a female connector on one end and a cable-mounted male connector the other?

Looks like not extremely much more expensive, only slightly more difficult to find.

Of course, you're both right. Why go for the simple option, when a much more complex solution exists

I have a tube-extender cable from the matchbox copro adventure: I seem to remember there was a hazard of some sort with using the wrong thing and letting the smoke out?

I think you run this risk if you try to use a cable with a female connector at both ends, and assume you can just use a pin header to connect the female end of the ribbon to the female connector on the level shifter. If you try to do this you end up with an incorrect pin assignment.

[BigEd]

Ah, I think this was the hazard: trying to approximate a male-to-female extension by combining a male-to-male with a female-to-female will end in disaster.