PCBs

discuss both original and modern hardware for the bbc micro/electron
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BubbleWrap
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PCBs

Post by BubbleWrap » Sun Nov 22, 2020 5:58 pm

While I'm waiting for the parts to fix my beebs, I thought I'd show off the PCBs i've been playing with :)

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EcoPort Issue 1 - slots into the econet header on a master, and gives you a 6522 at &FEA0. On these boards, the 6522's ~IRQ line is connected directly to the ~NMI line, so they need modifying to use interrupts on the extra 6522 properly.

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EcoPort Issue 2 - the big brother of Issue 1. Connect a flying lead to A4 and you get two 6522s, one at &FEA0 and one at &FEB0. These boards have a pin header that can either act as a place to attach a flying lead for the ~IRQ line, or a jumper to bridge the 6522 ~IRQs to the ~NMI line. Untested at present due to master dying (hence why most of the board is unpopulated).

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Modem to EcoPort Bridge - made so I could experiment with the internal modem header, it adapts the modem header pinout to match the econet header pinout (requires a flying lead for A3). I have one of my ecoport boards configured to connect to it so I can test it all out.

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EcoSound - a 6522 driving a YM2149 and using the econet socket as an audio out. I couldn't get the YM2149 working directly on the bus, so I have the 6522 on there acting as a go-between. The MC14066 is connected to the 6522's B port, and lets you enable/disable any of the four outputs through software (two pins on the econet port to provide stereo out, and the speaker out and aux out headers on the PCB). A speaker in header lets you feed the internal audio into the mix as well. The unfitted Port A and Port B headers on the PCB are the YM2149's IO ports, not the 6522's.

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EcoNet Expansion Board - the last one I was working on before the master gave up and died. If it's working, this board has an econet module with built in econet clock, and also a 6522 sitting at &FEB0 (requires the A4 flying lead). It also decodes the unused address space in the &FEA0-&FEAF range, allowing for another daughter board to be fitted with something else on, sitting at &FEA4, &FEA8 or &FEAC.

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These ones aren't my designs, but came with a bundle of stuff on ebay. From poking at the green one, that has socketed ICs, they seem to be 16K to 2x8K adaptor boards with a copy of MOS on. When the model B is up and running, I'm thinking of testing them in there to see if they still work. Also the ICs are north-facing but the sockets are facing south, and this irritates me so much. The green one says '203,011 S2 Iss 1', and the white one has some faint traces which I think used to say '203,011 S1'

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Diminished
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Re: PCBs

Post by Diminished » Sun Nov 22, 2020 6:02 pm

These look great.

chrissawer
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Re: PCBs

Post by chrissawer » Sun Nov 22, 2020 7:32 pm

BubbleWrap wrote:
Sun Nov 22, 2020 5:58 pm
These ones aren't my designs, but came with a bundle of stuff on ebay. From poking at the green one, that has socketed ICs, they seem to be 16K to 2x8K adaptor boards with a copy of MOS on. When the model B is up and running, I'm thinking of testing them in there to see if they still work. Also the ICs are north-facing but the sockets are facing south, and this irritates me so much. The green one says '203,011 S2 Iss 1', and the white one has some faint traces which I think used to say '203,011 S1'
They are probably OS 1.0 split across 2x8K chips, you can see one on the cover of BBC Micro Compendium by Jeremy Rushton, and also in the following thread from October: viewtopic.php?f=3&t=20737

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jms2
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Re: PCBs

Post by jms2 » Sun Nov 22, 2020 9:47 pm

Very impressive work!

The Econet module with integrated clock is particularly interesting... I have never dabbled in Econet myself, partly because it all seems rather expensive once you start adding up the price of Econet modules, clocks, cables and so on. I really like the idea of a build-it-yourself module with a clock in it. I realise it might not be a lot cheaper overall, but I just like soldering stuff together!

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geraldholdsworth
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Re: PCBs

Post by geraldholdsworth » Mon Nov 23, 2020 9:59 am

Yes, very impressive.

My favourite is the modem adapter. I've already got an Econet User Port board, but I wonder if I could add another couple of user ports...or do they use the same addresses?
No reason, just because.
Gerald Holdsworth
Repton Resource Page
www.reptonresourcepage.co.uk

BubbleWrap
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Re: PCBs

Post by BubbleWrap » Mon Nov 23, 2020 10:44 am

jms2 wrote:
Sun Nov 22, 2020 9:47 pm
Very impressive work!

The Econet module with integrated clock is particularly interesting... I have never dabbled in Econet myself, partly because it all seems rather expensive once you start adding up the price of Econet modules, clocks, cables and so on. I really like the idea of a build-it-yourself module with a clock in it. I realise it might not be a lot cheaper overall, but I just like soldering stuff together!
The clock is one I found online that uses an ATTiny to generate the signals. Instead of making it an external box with sockets, I wired it directly to the clock lines on the board. I figure for a planned network of 2 beebs a foot apart it ought to be sufficient. I'll post a link to the clock I found when I get home from work.
geraldholdsworth wrote:
Mon Nov 23, 2020 9:59 am
Yes, very impressive.

My favourite is the modem adapter. I've already got an Econet User Port board, but I wonder if I could add another couple of user ports...or do they use the same addresses?
No reason, just because.
The 6522 on the modem adaptor picks up the internal modems address, so it can be used in addition to the econet one.

I was looking through the FE memory map, and it seems there are quite a few places you can sneak in an extra 6522 if you intercept the chip select and decode the A4 line. The econet and modem are two of the most easily usable internal ones, and I'm also looking at the cartridge slots and 1mhz bus to see what I can fit in there once the machines are back up and running.

BubbleWrap
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Re: PCBs

Post by BubbleWrap » Tue Nov 24, 2020 2:35 pm

I forgot yesterday. This is the clock schematic I used. https://www.waitingforfriday.com/?p=19

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