General Stuff(tm)

Blogs & guides and tales of woo by forum members.
User avatar
rubber_jonnie
Site Admin
Site Admin
Posts: 10472
Joined: Thu Aug 17, 2017 7:40 pm
Location: Essex
Contact:

Re: General Stuff(tm)

Post by rubber_jonnie »

stephen_usher wrote: Tue Jan 25, 2022 9:53 am It feels as if everything is in courier limbo at the moment.

I'm waiting on the delivery of not only the QS8888 but also ISA/PCI BIOS post diag card (looks like Chinese eBay seller pretending to be in the UK) and a 486DX2-66 "Overdrive" CPU. Then there's the package I sent to someone yesterday.

Sigh
I know the feeling!!
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...
User avatar
stephen_usher
Posts: 5580
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: General Stuff(tm)

Post by stephen_usher »

Well, in lieu of the other stuff arriving I went in search of a newer BIOS for the machine.

After wasting a couple of AT27C512R chips on incompatible BIOS images I came across the archive of MRBIOS bios images. These are generic BIOSs aimed at specific chipsets and seem to cover all bases. There was a UMC48X with local bus and Weitek socket. That works a treat and has far better support for IDE in that it can read the drive details. It still can't do LBA unfortunately though, even though it's from 1994.

However, it does do a full check of the cache at power on and notices that something bad is afoot. This is far better than the original AMI bios which blindly tries to use it.

The one down side is that the user interface used to configure things is far less intuitive.
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.
User avatar
stephen_usher
Posts: 5580
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: General Stuff(tm)

Post by stephen_usher »

Bother! The second (larger) hard drive has just failed in the 486.

Oh well, it was the noisy one and with this new BIOS I may be able to get the 10GB ex-iMac drive usable instead.
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.
User avatar
stephen_usher
Posts: 5580
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: General Stuff(tm)

Post by stephen_usher »

Another issue which appeared last night was that it's getting harder and harder to boot the machine after it's been off for a while.

The power output from the PSU is fine, so it has to be the motherboard.

Previously it's just been a case of switch on and then press the reset button. Now it's taking longer and longer after power on to react to the reset button reset to initialise the video and POST. Sounds awfully like a capacitor, but there are no electrolytics on the board and tantalums generally don't fail that way, they either explode after going short or not work at all.

I really need this POST board to arrive to do any more diagnostics here.

P.S. I rescued the twin system to this a couple of years ago and it had the same (needing to press reset) start-up issue.
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.
User avatar
rubber_jonnie
Site Admin
Site Admin
Posts: 10472
Joined: Thu Aug 17, 2017 7:40 pm
Location: Essex
Contact:

Re: General Stuff(tm)

Post by rubber_jonnie »

stephen_usher wrote: Wed Jan 26, 2022 8:22 am
P.S. I rescued the twin system to this a couple of years ago and it had the same (needing to press reset) start-up issue.
Interesting that they both have the same issue. I'd have thought capacitor too, but with no eletrolytics where do you go with it! Could it be a failing IC in the reset circuit?

I'm assuming that the PSU is good at this point?

POST board should help, fingers crossed it arrives soon.
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...
User avatar
stephen_usher
Posts: 5580
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: General Stuff(tm)

Post by stephen_usher »

rubber_jonnie wrote: Wed Jan 26, 2022 9:45 am I'm assuming that the PSU is good at this point?
Yeah, all voltages are spot-on, all the power rails are clean and the "power-good" line comes up correctly.
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.
User avatar
rubber_jonnie
Site Admin
Site Admin
Posts: 10472
Joined: Thu Aug 17, 2017 7:40 pm
Location: Essex
Contact:

Re: General Stuff(tm)

Post by rubber_jonnie »

stephen_usher wrote: Wed Jan 26, 2022 10:46 am
rubber_jonnie wrote: Wed Jan 26, 2022 9:45 am I'm assuming that the PSU is good at this point?
Yeah, all voltages are spot-on, all the power rails are clean and the "power-good" line comes up correctly.
Bit of a head scratcher that.
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...
User avatar
stephen_usher
Posts: 5580
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: General Stuff(tm)

Post by stephen_usher »

Well, the 486dx2-66 Overdrive processor has arrived.

Looked at the From address on the label and surprised that it's from Dave Stevenson, the person who runs the main Memotech resource web site and who produces the CFX add-ons. It's a small world.
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.
User avatar
rubber_jonnie
Site Admin
Site Admin
Posts: 10472
Joined: Thu Aug 17, 2017 7:40 pm
Location: Essex
Contact:

Re: General Stuff(tm)

Post by rubber_jonnie »

stephen_usher wrote: Wed Jan 26, 2022 12:09 pm Well, the 486dx2-66 Overdrive processor has arrived.

Looked at the From address on the label and surprised that it's from Dave Stevenson, the person who runs the main Memotech resource web site and who produces the CFX add-ons. It's a small world.
Yeah, I ordered the QL minerva ROM from eBay Germany and it turned out I was already chatting with the seller on the QL forum!!

Does the Overdrive run at 33Mhz bus speed?

It's been a while since I played with one, and the 486 I have is already a DX2/66, so I can't remember how they did it all.
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...
User avatar
stephen_usher
Posts: 5580
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: General Stuff(tm)

Post by stephen_usher »

rubber_jonnie wrote: Wed Jan 26, 2022 1:07 pm
stephen_usher wrote: Wed Jan 26, 2022 12:09 pm Well, the 486dx2-66 Overdrive processor has arrived.

Looked at the From address on the label and surprised that it's from Dave Stevenson, the person who runs the main Memotech resource web site and who produces the CFX add-ons. It's a small world.
Yeah, I ordered the QL minerva ROM from eBay Germany and it turned out I was already chatting with the seller on the QL forum!!

Does the Overdrive run at 33Mhz bus speed?

It's been a while since I played with one, and the 486 I have is already a DX2/66, so I can't remember how they did it all.
Yeah, the Intel DX2's are 5V and the 66MHz part basically clock doubles internally.
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.
Post Reply

Return to “MEMBER BLOGS”