My new beeb - A to B? But why no analogue?

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iamaran
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My new beeb - A to B? But why no analogue?

Post by iamaran » Sat Feb 16, 2019 1:21 am

Back in the day I had an Issue 7 Model B (presumably in silicon heaven as I sadly sold it to fund an Amiga). Now I'm the proud owner of an Issue 3 ICL built model.

My first impression of my new Beeb is that it is a Model A upgraded to B spec because 8 of the 16 RAM chips are clearly different.

The RS423 and RGB are present but the analogue isn't. The tube, user port, etc underneath are all there so my question is: this "Why would a Model A be upgraded to a B spec in every respect I can think of, except for the analogue port?"

Or did ICL do it differently? Am I missing something obvious? Or... ?

I can't/won't power it on until I replace the PSU caps or pay for that to be done for me.

Quick snaps attached, better photos can be taken this weekend.

Thanks for any input everyone.
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rear.jpg
under.JPG
ram.JPG
Last edited by iamaran on Sat Feb 16, 2019 1:34 am, edited 1 time in total.

duikkie
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Re: My new beeb - A to B? But why no analogue?

Post by duikkie » Sat Feb 16, 2019 6:51 am

Take a picture of thee pcb board in totale The bbc was a learning computer and te analoge port was for. Play ing :)
Last edited by duikkie on Sat Feb 16, 2019 6:51 am, edited 1 time in total.

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tricky
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Re: My new beeb - A to B? But why no analogue?

Post by tricky » Sat Feb 16, 2019 8:10 am

I've come across a couple where the connector has been hanging off and one where the d7002 was toast!

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1024MAK
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Re: My new beeb - A to B? But why no analogue?

Post by 1024MAK » Sat Feb 16, 2019 9:15 am

It may help if you have a look at the underside/solder side. Look at the component and chip pads. Flow soldered pads are normally clean and very consistent. If you see any flux (black/brown/tan coloured deposits) around solder joints / pads, or the solder joints are not consistent (varying amounts of solder on each pin/pad), these are signs of hand soldering.

As to why the analogue port connector was not fitted, we can only speculate. Are you sure it was never fitted? Or was it broken off? Is the analogue to digital converter (ADC) chip fitted?

It may be the owner at the time was not a game player, or maybe they hated joysticks. Or maybe the machine was only intended for serious use.

Mark
Last edited by 1024MAK on Sat Feb 16, 2019 10:42 am, edited 1 time in total.

cmorley
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Re: My new beeb - A to B? But why no analogue?

Post by cmorley » Sat Feb 16, 2019 10:00 am

Probably just cost. Why pay for it if you're not going to use it?

As Mark says some photos of the area and solder side might hint to the history of this machine.

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Re: My new beeb - A to B? But why no analogue?

Post by iamaran » Sat Feb 16, 2019 10:12 am

Thanks all. Now I look with eyes that aren't tired...
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Re: My new beeb - A to B? But why no analogue?

Post by 1024MAK » Sat Feb 16, 2019 10:31 am

So the ADC chip is fitted :?

Mark

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Re: My new beeb - A to B? But why no analogue?

Post by cmorley » Sat Feb 16, 2019 10:34 am

The chip is there. Perhaps the socket got corroded and was removed...

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tricky
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Re: My new beeb - A to B? But why no analogue?

Post by tricky » Sat Feb 16, 2019 10:37 am

As it has the A2D chip, I suspect it has been worked loose/broken and was there at some point.
Some beebs seem to have the 15pin connector "push" fit to the board, held in by the two screws.
I don't know if this is how they were supposed to be or if the pins have all broken off leaving little stubs, but either way over-tighten the screws a few times and you'll strip the threads and have no analogue port.

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1024MAK
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Re: My new beeb - A to B? But why no analogue?

Post by 1024MAK » Sat Feb 16, 2019 10:48 am

Some have a 15 way D connector that has solder tabs to secure it to the PCB rather than screws or machine screws/bolts and nuts.

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Re: My new beeb - A to B? But why no analogue?

Post by johnkenyon » Sat Feb 16, 2019 12:17 pm

The ADC socket looks like it's been installed and removed.
It's also got a speech synth upgrade installed - TMS5220 + TMS6100.

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Re: My new beeb - A to B? But why no analogue?

Post by tricky » Sat Feb 16, 2019 12:41 pm

I've replaced the resistor with a variable one on a couple of my issue 3 beebs where the speech frequency was too far off, but yours is probably fine if it was done by a dealer, also they don't have to be spot on, the pitch just sounds a bit off.

iamaran
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Re: My new beeb - A to B? But why no analogue?

Post by iamaran » Sat Feb 16, 2019 12:46 pm

Right, thanks everyone. Replacing it will be beyond my skills! I will get the PSU done (though it does look ok to this novice) and see whether it powers on.
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Re: My new beeb - A to B? But why no analogue?

Post by cmorley » Sat Feb 16, 2019 12:58 pm

It's the orange/yellow translucent RIFA caps that fail with the burning paper smell. They die with age so replacing them saves setting off your smoke alarm and so popping/fizzing noises + the lingering stench!

You can see one in the photo and the other is hiding under the mains wiring.

I replace them with Kemet poly caps which don't fail by way of fire and smoke. Others replace like for like but they will fail again given time.

They are easy to replace.

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Re: My new beeb - A to B? But why no analogue?

Post by iamaran » Wed Feb 27, 2019 8:40 pm

It lives!

BBC Computer 32K
Acorn DFS
BASIC

*H.
WORDWISE-PLUS 1.48
DFS 0.9H
DFS
UTILS
OS 1.20

The 5 ROMs are (I think):
IC51 HN613128PB04 OS 1.2
IC52 Torch Computers (but would appear to be Acorn) DFS .9H
IC88 Wordwise Plus 1.48
IC100 HN613128PB05 BASIC II
IC101 HN613128PB01 BASIC I

And Kenneth Kendal talks perfectly!

I'm sorry for all the questions that will surely follow, but it's been a very long time since I owned an issue 7.

Q1: Are my ROM assumptions correct from the photo? I do miss the *ROMS command!
Q2: Why two BASIC ROMs? REPORT replies 1981 suggesting BASIC I.

Thanks everyone.
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Pernod
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Re: My new beeb - A to B? But why no analogue?

Post by Pernod » Wed Feb 27, 2019 9:08 pm

iamaran wrote:
Wed Feb 27, 2019 8:40 pm
Q1: Are my ROM assumptions correct from the photo? I do miss the *ROMS command!
Correct, though I would like to see a dump of the DFS 0.9H.
iamaran wrote:
Wed Feb 27, 2019 8:40 pm
Q2: Why two BASIC ROMs? REPORT replies 1981 suggesting BASIC I.
You don't need both. It's finding BASIC1 first, simply remove it and REPORT will reply 1982.
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.

iamaran
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Re: My new beeb - A to B? But why no analogue?

Post by iamaran » Wed Feb 27, 2019 9:37 pm

Pernod wrote:
Wed Feb 27, 2019 9:08 pm
iamaran wrote:
Wed Feb 27, 2019 8:40 pm
Q1: Are my ROM assumptions correct from the photo? I do miss the *ROMS command!
Correct, though I would like to see a dump of the DFS 0.9H.
As soon as I'm in a position to do so, I promise to do this.
Last edited by iamaran on Wed Feb 27, 2019 9:38 pm, edited 1 time in total.

iamaran
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Re: My new beeb - A to B? But why no analogue?

Post by iamaran » Wed Feb 27, 2019 9:39 pm

Pernod wrote:
Wed Feb 27, 2019 9:08 pm
iamaran wrote:
Wed Feb 27, 2019 8:40 pm
Q2: Why two BASIC ROMs? REPORT replies 1981 suggesting BASIC I.
You don't need both. It's finding BASIC1 first, simply remove it and REPORT will reply 1982.
Yep, that works. Thanks! Odd, because the previous owner was savvy and has 3 or 4 in his (now my) collection (DiscDoctor, Exmon etc) that he could have replaced it with.
Last edited by iamaran on Wed Feb 27, 2019 9:45 pm, edited 2 times in total.

smokey
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Re: My new beeb - A to B? But why no analogue?

Post by smokey » Mon Mar 04, 2019 8:34 pm

to me. it looks like an "upgraded" Model A

BUT i might be very wrong.

If i am wrong why would a model b be missing ports.

James

iamaran
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Re: My new beeb - A to B? But why no analogue?

Post by iamaran » Fri Mar 08, 2019 8:01 pm

iamaran wrote:
Wed Feb 27, 2019 9:37 pm
Pernod wrote:
Wed Feb 27, 2019 9:08 pm
iamaran wrote:
Wed Feb 27, 2019 8:40 pm
Q1: Are my ROM assumptions correct from the photo? I do miss the *ROMS command!
Correct, though I would like to see a dump of the DFS 0.9H.
As soon as I'm in a position to do so, I promise to do this.
ROM dumped. Will post in Archive Submissions.

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