BBC Model B No2. Will it live again!

Any 8bit repairs, images, cool things, upgrades etc.
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rubber_jonnie
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Re: BBC Model B No2. Will it live again!

Post by rubber_jonnie »

stephen_usher wrote: Tue May 11, 2021 9:38 pm So, when it starts working, "Bob's your uncle"?

(Or, if you're a Blackadder fan, "Bob's your aunty".)
Yup, sounds about right :)
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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JezC
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Re: BBC Model B No2. Will it live again!

Post by JezC »

I'm kind of sad they didn't use Fred, Jim or Sheila...just to be consistent with the s/w! :D
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rubber_jonnie
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Re: BBC Model B No2. Will it live again!

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JezC wrote: Wed May 12, 2021 8:24 am I'm kind of sad they didn't use Fred, Jim or Sheila...just to be consistent with the s/w! :D
:dizzy:
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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JezC
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Re: BBC Model B No2. Will it live again!

Post by JezC »

@rubber_jonnie Sorry, possibly a bit too niche for non-BBC nerds ... :ugeek:

Those names relate to specific address ranges in the memory map...worth a search on the net if you want to learn some totally useless info ...

Sadly, I seem unable to forget these pointless bits of trivia & forget much more useful & important stuff instead!
:lol: :roll:
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Re: BBC Model B No2. Will it live again!

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JezC wrote: Wed May 12, 2021 11:32 am @rubber_jonnie Sorry, possibly a bit too niche for non-BBC nerds ... :ugeek:

Those names relate to specific address ranges in the memory map...worth a search on the net if you want to learn some totally useless info ...

Sadly, I seem unable to forget these pointless bits of trivia & forget much more useful & important stuff instead!
:lol: :roll:
Lol, all good to me, I like nerdy stuff :)
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: BBC Model B No2. Will it live again!

Post by rubber_jonnie »

Ok, so I'm about halfway through the socket replacement program with major chips now in new sockets. The fault remains though, so no further down the path.

I think I'll take up an offer on stardot of Tricky's diagnostic ROM (Can't burn one myself ATM) as that may give me the answers I need.

In the meantime I will continue replacing the awful sockets as I simply don't like them and don't think they can be helpful if I want to make this machine last another 40 years :)
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: BBC Model B No2. Will it live again!

Post by rubber_jonnie »

Ok, so all the RAM sockets have now been replaced too, as has the socket for the reset chip, which, surprise surprise, is a 555.

No change to the symptoms though, which is pointing me at a couple of things:

1. RAM - Removing the RAM makes no difference, so perhaps a look at the cas/ras select logic.
2. ROM - If the OS ROM is nadgered (Yes, it's a technical term) then nothing will happen.

I must go and double check what happens if I try to boot with no CPU, see if the problem remains. I think I did, but don't recall the outcome.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
BennehBoy
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Re: BBC Model B No2. Will it live again!

Post by BennehBoy »

What sockets are you using for the replacements? There seems to be a lot of differing viewpoints between turned pin and double wipe with folk being equally vocal about the benefits of both kinds. (I've got plenty of both here, mainly in 24 & 28 pin for making ROM adapters).

I've been thinking of upgrading my breadbin C64 to be fully socketed so I can use it as a test platform, and I spied these beautiful low profile zif sockets that someone else has used: https://www.arieselec.com/product/10018 ... st-socket/

I was all set on them until I saw the prices ~10 quid each!
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Re: BBC Model B No2. Will it live again!

Post by stephen_usher »

It's probably the bus buffer chips, they're always a bit flakey on all machines. Without a decent oscilloscope though it's rather a case of flying blind.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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Re: BBC Model B No2. Will it live again!

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BennehBoy wrote: Sun May 16, 2021 4:11 pm What sockets are you using for the replacements? There seems to be a lot of differing viewpoints between turned pin and double wipe with folk being equally vocal about the benefits of both kinds. (I've got plenty of both here, mainly in 24 & 28 pin for making ROM adapters).

I've been thinking of upgrading my breadbin C64 to be fully socketed so I can use it as a test platform, and I spied these beautiful low profile zif sockets that someone else has used: https://www.arieselec.com/product/10018 ... st-socket/

I was all set on them until I saw the prices ~10 quid each!
Personally I'm not a fan of turned pin sockets for chips and much prefer double wipe where the surface area in contact is much larger. Turned pin is fine if you're plugging in turned pin adapters, I just don't see any benefit for chips.

Adrian of Adrians Digital Basement has a C64 with ZIF sockets, though I don't think they are low profile.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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