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ATPL Sidewise

[22nd April 2014]

My latest BBC Micro-related eBay purchasing has arrived: an ATPL Sidewise sideways ROM/RAM expansion! Woohoo! It cost £28.00 + £3 P&P and sold as untested/possibly not working due to a broken pin. Cost-wise not too shoddy if I can get it working.
This product allows for the expansion of the total number of physical Paged ROM sockets on a standard BBC Micro model B from the standard five to fourteen sockets + a hybrid RAM/ROM sockets plit into 2 sockets (I'll explain later). It won't work on a model B+ due to the existign ROM sockets being in a different physical location (and so the Sidewise board won't fit). Click HERE for an overview of what sideways RAM / Paged ROMs are.

Here's the outer packaging & booklet:

RemoveScrews

As you can see, it's seen better days, although the manual seems fine. Nothing to complain about considering its age and that it's very much second hand.
Here's a link to the manual.

Inspection

RemoveScrews RemoveScrews

The top side of the board looks ok with no physical damage that I can see. The 28 pin IC sockets, smoothing/decoupling capacitors, logic ICs and other components don't have any visible damage.
The underside is, unfortunately, a little different. The first SIL type pin package looks fine (top left), but the second one (lower right in the picture) has a number of bent pins and one which has been broken off entirely.

The battery & relevant components which are used to keep the optional RAM chips in IC 15a and 15b powered when the host computer is off are not present. Reading the manual, it seems that this battery kit is/was an optional extra and although RAM contents will be lost on power off without it, does not otherwise affect the operation of the Sidewise daughter board.

Markings-wise, the board is clearly mark with the Sidewise logo and description, along with the ATPL logo, the board model/issue (1038i issue 4), the production date (1983) and the serial number (4/28.510.21965) I assume the first figures correspond with 28th April? So this board could ahve been made on 28th April 1983. Only 21 years ago then lol.

Repair

The first order of business is to replace the broken pin. The only choice that needs to be made is should I replace the entire row of SIL pins or just that pin? I think I'll go with just the one pin for now, but if that doesn't work out will do the whole row. Here's a close-up of the damage:

RemoveScrews

I haven't got any proper replacements of the same type of pin, but I do have something which might work - a pin header. It's a little too short really, but I think if I might just be able to wangle it. My only other concern is that it's a little thicker than the original.

Well, here's the repair. It's not overly pretty, but it does buzz out fine from the ROM socket on the topside of the board that it's linked to, so... I assume it'll do the job. Here's a piccy:

RemoveScrews

Also, I've replaced the fly leads which go from the Sidewise board to the lower S21 pin on the mainboard as the ends had been slightly mangled. For this I've recycled the pin-connector end of a reset button from an old PC to use on S21 (which is great for easy plugin and removal). It also gives a longer cable, although I had to break to plastic of the connector off about halfway down so that I could bend it to a right angle - otherwise it would get in the way of the Sidewise daughterboard.

Fitting

I connecting the board didn't pose too much of an issue, although I did run into a few issues. I followed the instructions in the manual:

* Removed the case and keyboard/speaker.

* Removed the OS ROM from the IC51 socket on the mainboard and the ADC IC from from the IC73 socket.

* Carefully bent the middle two power connections on the mainboard from the power supply unit to a rough right angle (so they lay flat)

Bending_Power_Leads

* Removed the jumper from S20 (centre of the mainboard). The labelling on most BBC Micros will be misleading, seemingly showing S20 right at the bottom of the small jumper group. This is not the case. S20 is immediately beneath S21 and has pins going to east-west orientation, not north-south.

Jumper_S20

* Connected the fly leads to S20. Although the fly leads come out of the underside of the Sidewise board, the markings for them are on the top side (not mentioned in the manual). The fly lead marked EI needs to be connected to the EAST (right) pin of S20 and the one marked EO to the WEST (left).

Flylead_Markings

* Fitted the Sidewise daughterboard so that the socket marked IC73 plugs into IC73 on the mainboard and the IC51 to the corresponding socket on the IC51 mainboard.

* Fitted the OSROM to IC51 / the ADC IC to IC73 on the Sidewise board

SideWise_fitted2

* Forgot to move the Basic ROM to IC socket 14. Normally this would be 15 (the highest priority socket), but 15 is used by the two optional 8K RAM/ROM sockets. Now fitted:

SideWise_fitted


* Re-fitted the keyboard/speaker and the case.

 

 

Results

It powered up fine into BASIC with the DFS showing.
One big issue is that my MMC ROM* doesn't enable. I initally thought that this might be down to the ROM chip dying, but it worked fine on my model B+. It did previously work on the model B prior to the fitting fo the Sidewise board. I think this might be down to ROM type whcih is controlled by links on the daughterboard. I'll look into that later. I proved that other ROMs work by also fitting a Wordwise Plus ROM from my B+.

SideWise_fitted
* This ROM accesses an MMC card reader connected to the User Port, allowing me to load up tons of disc images. Extremely useful!

I'll update this page as and when I do more testing, but over all this has been quite successful :)

 


Minor update [23rd April 2014]

After reading the manual a bit more, it occurs to me that changing the "jumper" settings on the Wisdewise board is less than easy: they're just enlarged via holes with premade "default" settings links (i.e. solder links beneath for the default settings).
I've cut these links and soldered in pin headers and added in jumpers in the default positions (for no battery fitted and 16K ROMs):

SW_jumpers1 SW_jumpers3 SW_jumpers4

I've now got 2x 8KB HM6264LP-70 SRAM chips. I'll post an update once I've received them.
I'm also looking at finding the optional battery kit or will see if I can design and/or build my own.

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