I’ve added a new page in my info section about these. Read more about it here.
If you have one of these, you will have discovered that the last revision of firmware than can run on these is A08, because the single PLCC-44 socket can only hold at most a 4 mbit EPROM.
Later PCBs have two EPROM sockets allowing them to run newer (larger) firmware images.
Strictly speaking however, there’s nothing stopping us from running ‘B’ firmware on these older units, if only there was some way we could get a little more ROM space.
There’s no PLCC-44 EPROM we can put in that socket which can hold more than 4 mbits, however…
I have built an adapter which makes this possible. It’s pretty simple. It’s got a PLCC-44 plug and a PDIP-42 socket to allow, for example, an M27C322 (32 mbit) to be used in place of the original ROM. I used a 42-pin EPROM because they’re common, dirt cheap and easy to program with cheap hardware.
It is secured in place using a hex spacer mounted on an existing screw hole on the digital PCB.
After having built this I discovered that my choice of PLCC plug (Winslow W9303) is made (and only available) in the UK – so this project is probably a fat lot of good to anyone else, but the none-the-less the point is proven here, it is possible to get to the latest firmware on these oldest units.
One little wire mod
Sadly we do have to make a little change to the PCB to facilitate this new adapter:
An extra address line from the CPU has to be connected through to pin 1 (unused) of the EPROM socket. The other end of this wire is visible in the previous image (it is connected to the 5th pin from the top left corner of the CPU). Because this pin is NC on the stock EPROM it can be left in place if you wish to return to the original Axx firmware.
Calibration data troubles
After having booted my 2001 with (more or less) the latest firmware (B16) I discover that the calibration data hasn’t loaded, and on top of that it’s gone and wiped the calibration memory on boot-up. FFS.
It turns out that the format of the calibration memory is different between the original firmware (A08) and what I’ve upgraded it to (B16). Referring back to the great oracle of Keithley 2001 related information (xdevs.com) one of the images he’s got up there (link) appears to be in the same format as what I’ve upgraded to, so I edited the binary to put my serial number into it, flashed that into mine, and I’m back in business, albeit with someone else’s calibration coefficients. Eh. I don’t care, my cals were a decade out of date (long overdue to be re-done) anyway so no big loss.
Once the calibration EEPROM is changed to ‘B’ format it’s no problem to change between all ‘B’ versions. I do not know how to convert them unfortunately, that would be a separate project.
If building one exactly like mine – the 27C322 is large enough for 4 B-Revision ROMs. Jumper settings will determine which to boot.
The only tricky part to source is the PLCC-44 plug – which is a Winslow W9303. Unfortunately these are only available in the UK and there is no alternative. Sorry about that!
- 1x Winslow W9303 PLCC-44 plug
- 1x 0.1 uF ceramic capacitor
- 1x M27C322, M27C160 or M27C800 EPROM
- PDIP-42 socket
- 2x right angle jumpers
- M3 15mm hex spacer + screws + washers
If using an M27C160 it’s only possible to fit two firmware versions in, which would be toggled by the A19 jumper. The A20 jumper should be set to ‘L’.
In the case of the M27C800 – only one firmware image will fit. The A19 jumper must be set to ‘L’, and the A20 jumper must be set to ‘H’.
If you don’t have a computer with PCIe expansion slots – there are no easy and inexpensive ways of attaching an LTO tape drive to it.
For quite some time now I’ve been doing my backups (including all of the content on this website) by Tape. Why? Quite frankly I just like them. If like me you buy older generation drives second hand for personal backup, I find it actually works out cheaper than having say, two or three (or more) USB hard disks. The low cost of the media also allows me to have a history of my data (say, a copy from each year), because sometimes, things get lost or corrupted, I don’t realise it, then end up overwriting a good (backup) copy of data with bad (or no) data.
There are other significant benefits of tape – particularly in the robustness and simplicity of the media. Tape media is purely mechanical (aside from the RFID chip on the side) meaning that there’s no electronics which can be damaged. The physical spool of tape is also very robust, unlike the glass platters of a hard disk.
Dropped your tape and smashed it? Somehow managed to kill that RFID chip? No problem. Just buy another tape, undo the four Phillips screws on the bottom and transfer the tape spool to another shell, and you’re back in business. Good luck doing anything like that on a hard disk!
Happened to be subject to a massive electrical surge or lightning strike while your one and only copy of data on a tape was in the drive? Once again, no problem. Tapes have no electrical connection to the drive whatsoever, even during operation.
When talking about backup, IT administrators often use the term “air gap” meaning that data cannot be wiped out by a virus or other accidental software or power incidents. Tape, today, remains the undisputed the king of air gaps.
LTO Tape drives (these days) come with either Fiber Channel, or SAS interfaces – there are no other options. This makes them a little difficult to attached to (For example) a Mac, or any Laptop. Desktop PCs & Mac Pro’s are not an issue because you’ll likely have PCIe slots where a SAS or Fiber Channel host adapter can be installed.
I don’t actually have any PCs with PCIe slots in them anymore, and haven’t had for quite some time so have had to confront this issue myself.
Before we get into the topic of attaching drives, it may be worth considering the drives themselves – assuming you haven’t already purchased one.
Despite a range of different brands, there are two manufacturers of LTO tape drives: HP & IBM. We can see this in the picture with our top drive having an IBM style blue button like what is found on their servers and desktop PCs, and the bottom drive featuring HP’s corporate font under the LEDs.
Dell models feature a slightly different chassis however they are still IBM drives.
Both are very well engineered as you can imagine for the large price paid for these units purchased new.
There are some things to consider (in the context of tabletop drives) when choosing one over the other:
IBM Tabletop Drive
- Slimmer more aesthetically pleasing design
- Good full featured LTFS implementation for Windows
- Easy single handed tape insertion – like a VCR
- Slightly more pleasing operational noises
- Very robust all metal chassis
- Easy to dismantle (four screws on the underside, cover slides off)
- Extremely noisy high-RPM 40mm fan on rear, always runs and restricts the drive to server room use only
- Terrifying high pitched sound when loading tape
- Mine seems to jam during loading about 1 in 10 times – requiring a second attempt
- Drive is very long (340mm), may not fit on some shelves
- “Soft” power switch. Power supply is still on even when drive is off
- An extra $1000 for an IBM branded one (grumble)
HP Tabletop Drive
- “Fat” design thermally superior to IBM’s. Uses larger, quieter fan
- Fan is only on when tape is inserted, goes unto standby mode when empty (thanks to a fan output connector on the drive its self) – likely applies to LTO-6 drives and earlier only.
- Shorter than IBM drive (300mm)
- Full AC power switch on front (I think)
- LTFS Implementation for Windows less featured than IBMs (LTO-6 and earlier). Depending on your use case you may also want to supplement it with this.
- Operational noises a little more irritating than the IBM drive
- LTO-6 and earlier drives have a “flap” which has to be lifted up to insert a tape making it a two hand job. If you use the drive a lot – this is going to piss you off.
- Outer plastic chassis not as robust as IBM drive (there is also an inner metal chassis).
- Complicated chassis design must be dismantled in a very specific way to avoid breaking internal plastic clips.
Side note: I have made several references to “LTO-6 and earlier” here. This is because the last generation of drive made by HP was LTO-6. From 7 onward, HP drives are re-branded IBM drives deployed in HP’s traditional black plastic chassis.
Option 1: USB
Some time ago a product existed to convert USB to SAS:
They originally sold for around US $250 but likely due to the decline of SAS usage in general, do not appear appear to be made anymore. They can still be found for sale, for typically very high ($500+) prices. If you can get your hands one for a good price, this may work out, but don’t count on being able to get another.
Assuming you can obtain one of these rather exotic items, you would then need an internal SAS to SFF-8088 cable, bearing in mind that SFF-8088 carries 4 SAS lanes, you’d just connect your USB to SAS adapter to port 1 – which is what the tape drive will be internally connected to. This would be a workable setup – but a bit ugly.
Due to the obscene cost and obscurity – I would not recommend going down this path.
Option 2: Thunderbolt (buy one pre-made)
If you’re not technical and/or not on a budget, there are a few ready-made Thunderbolt drives. These internally contain a PCIe to SAS host adapter as I demonstrate below. Expect to pay a $2000-3000 premium for this convenience. A product like this uses an ATTO or Highpoint SAS controller which is required for compatibility with macOS X – the primary target market for these products.
Option 3: Thunderbolt (pre-made SAS adapter)
This will be a little cheaper than buying a pre-built drive but still a lot more expensive than the option below. You’ll have to source the appropriate SAS cable. More about that below.
Option 4: Thunderbolt (make your own)
This is a far more sensible (and cheaper) option. Because Thunderbolt carries PCIe we can use (For example) an eGPU enclosure to carry a PCIe SAS Host adapter.
I personally use an LSI SAS9207-4i4e. The LSI SAS9207-8e (two external ports) would also be suitable, as would many others. I have chosen this because it is a fairly recent adapter, which also has the very same SFF-8088 connector found on the tape drive. I got this adapter off eBay for $30.
The full setup
To the left we have a PCIe Thunderbolt enclosure containing the Host Adapter. There are lots of Thunderbolt PCIe enclosures on the market, you can pretty much just pick the cheapest one as a SAS Host Adapter is not a very demanding card to install in one. Single slot enclosures seems to be the cheapest at around $200 at the time of writing.
To the right is the tape drive.
If we go down this path, in addition to only having spent $300 (excluding the cost of the drive), we also have the bonus of having a few new items that have other uses. For one the Thunderbolt enclosure can be used for other PCIe cards, also the SAS Host Adapter can be used as a very high performance connection for SATA hard disks too. There are many different cables and enclosures which can make use of this.
SAS cable selection
SFF-8088 cables come either x1 (one lane) or x4 (four lane) variants. A tape drive only has one lane so either an x1 or x4 cable will be OK. x1 cables are considerably thinner and lighter than x4 cables.
You can also buy fairly long SAS cables too. Bear in mind that tape drives are quite noisy, you may want to consider buying a longer cable (up to 10M / 33ft) so you can put the drive somewhere it’s not going to irritate you.
There are multiple type of external SAS connector presently in use and these days SFF-8644 is beginning to replace SFF-8088 despite it still being common on tape drives. It’s not a problem if you end up having to buy a SAS Host Adapter which has a SFF-8644 connector on it, you’ll just have to buy a cable which has the appropriate connectors on each end.
Operating system (Windows/Linux)
On Windows 10 I did not have to install any drivers for the Thunderbolt enclosure or SAS Adapter – it all just worked.
The only driver I did have to install was for the tape drive its self.
Linux is even easier with all of the necessary drivers built into the kernel.
Operating system (macOS X)
There will not be any driver issues with either the Thunderbolt enclosure or the tape drive – they will work out of the box.
The issue arrives with the SAS host adapter. Unfortunately native SAS support is quite poor in macOS with only a handful of ATTO and Highpoint chipsets supported. It is these chipsets which are found in expensive ready-to-go solutions I have previously mentioned.
If you are lucky you might get one on a PCIe card for a decent price. Pictured above is an ATTO ExpressSAS H644 which you conceivably may be able to pick up second hand for a less than bank-balance-busting price but I wouldn’t count on it. Honestly, if you’re an Apple person, it’s likely not worth the hassle for you. Magstor’s $5500 drive will work a treat.
As it happens I do own a Mac, and I’ve managed to pick one of these up for a very reasonable price second hand, so let’s try it out…
The ATTO worked out of the box. I didn’t have to install any additional driver packages. LTFS detected the drive and mounted it just fine. LTFS is not a very good “experience” on macOS – and since experience the reason you have a Mac, you’re probably going to want to look at some commercial backup software to run your tape drive, of which there are many choices.
As was to be expected, my LSI adapter wasn’t detected by macOS, nor are there any drivers available for download.
I found that it all works like a charm. You can either hot plug the whole setup through the Thunderbolt cable, or you can just disconnect the SAS cable (or even power off the drive), as SAS is also hot-pluggable, if for example you use your SAS host adapter and PCIe enclosure for other things (as I do).
Fiber Channel instead of SAS
You could also substitute a PCIe SAS adapter for a Fiber Channel host adapter in your Thunderbolt enclosure if that’s the kind of drive you happen to have. You can do your own research on that. This is going to be a lot more complicated but the advantage of this option is that you could have your tape drive a very long way from your PC.
Are SATA adapters of any use?
For the most part, no. If you are starting with a SATA/eSATA controller, there is no way to adapt to SAS. You must start with a SAS controller. SAS controllers however, support either.
There are some scenarios where SATA to SAS/SFF adapters are useful – for example:
Let’s say you have a SAS controller with a bunch of SATA HDDs attached via a SAS to SATA octopus cable, and you happened to have a spare port – it is possible to adapt that port back to SAS, to attach to a SAS tape drive.
Essentially – it doesn’t matter if intermediate the cabling or connectors are SATA, just so long as you have SAS hardware at either end. SAS and SATA cables & connectors are eletrically the same i.e. 2x 100Ω differential pairs each – differing only mechanically.
It also doesn’t matter that you are using a mix of devices on one host adapter – so long as you’re not trying to put those devices into a single RAID volume – SAS controllers don’t care.
Because the tape drive will only be using one port on the SFF-8088 connector, you can connect that one spare SAS port to port 1 on the adapter.
Older laptops with ExpressCard slots
There are some products which adapt ExpressCard to PCIe which would allow a SAS adapter to be attached.
There are some examples of SAS ExpressCard adapters:
Very few true SAS ExpressCard adapters like the above were ever made. None are made anymore and anyone who has one may expect a high price for it.
Most products resembling the above are 4x SATA controllers with an SFF-8088 connectors, which is of no use for tape drives.
Imagine you’re stuck at home under lockdown. What to do? All those things we thought we’d never have time for.
This weekends’ creation is a command line tool for configuring LTFS on Windows.
It has occurred to me that I’ve got quite a collection of these – and have written an article on this subject.
Read more about it here.
Half width Agilent / Keysight instruments made up until the late 2000’s had a plastic back bezel (34401-88304) which the rear bumper attaches to. They are frequently broken in electronic labs because the rear bumper often slides off the end of the desk. Someone then grabs the instrument to pull it forward, not knowing it is caught on the back edge of the desk, destroying this part in the process. After the 100th time trying to glue mine back together – it was time to get a replacement.
They are frequently seen for sale on eBay for $100 or more, but the part’s true cost from Keysight is only around $12 – if you can be bothered with the hassle of ordering it directly from keysight – Which brings me to my point here.
Where U.S. Customers can order with ease directly from the website – getting this part in the UK involved 12 emails, 4 phone calls, to people in 3 different countries, and hours of both mine and Keysight’s time. In the end I was charged just £14 (including VAT and shipping). Ridiculous. Keysight likely spent £1000 of their own time getting me this part.
I am not faulting the service here – Given the rigmarole I am astonished at how little this cost! It even comes in a ludicrously oversized box:
I ended up having to collect in person from Mayfair post office – who are never thrilled to have to hold large items – resulting in the spectacle of me carrying this large geeky box through the crowded streets of Central London (not that a single person would have recognised that logo).
Yeah… just the shipping alone would have cost £14.
In the end a rare example of dealing with a big brand like this, without punishing my credit card in the process. I also have some Keithley parts to order this month. That is not going to be quite so cheap.
Recently I purchased a Plextor PX-40TSi SCSI CD-ROM drive from eBay. It was described as being in “excellent” condition and unusually it came with all of the retail packaging, manual & accessories which was re-assuring. This particular one was very reasonably priced considering that these drives, despite not having made for some 20 years now, remain stubbornly expensive – commonly fetching $50 second hand.
This is because they are commonly found in older non-PC industrial, professional audio, electronic/RF and medical equipment which is still in use and valuable, and as a result of this people still buy up these drives to fit or replace existing units. Compounding the problem there are annoying people like myself buying them to connect to ancient computers for no good reason.
This of course is all nothing compared to Plextor SCSI CD-RW Drives. The PX-W4012TS (40/10/40) still fetches an astonishing $500 price tag. A quick bit of research reveals these may be being used for vintage Akai DPS units, but that doesn’t quite seem to justify that kind of price tag. If you know anything more – please drop a comment!
My Agilent 16702B is an example of an older piece of equipment which uses a SCSI CD-ROM drive. SE drives like this one tend to fetch a higher price than newer LVD drives too for some reason.
When I unboxed this unit, I quickly noticed the plastic around and on the eject button was noticeably worn. This drive has clearly had a lot of use. I plugged it in, pressed eject and the tray came out with a horrendous grinding noise. It was also apparent that it was full of dust, dirt and even quite a lot of hair. Yuck!
Upon inserting a CD, it spun up with a terrible screeching noise, and down, and up, and down, and so on, but never managed to read a disc. I complained profusely to the seller, who immediately refunded all of my money, leaving me with this piece of junk of a drive.
With the tragic 2019-nCov outbreak in China likely to leave me without the PCBs for my next project for quite a while – this has left tech-time a little aimless to say the least. What more can one do than spend some of that time to see if I can bring this thing back to life while we wait and hope for the best.
Problem 1: Drive full of crap
A quick blast with compressed air sorted that out.
Problem 2: Can’t read any discs
My first thought was to dab the lens of the laser with a cotton tip soaked in isopropyl alcohol. Astonishingly this fixed the problem. This trick sure as heck hasn’t fixed any other faulty optical drive I’ve had over the years. With the drive now demonstrated to be functional, we can now push on and tackle the rest of the issues.
Problem 3: Grinding noise when ejecting the tray
This was a nice easy one to fix. I just pulled all of the gears out, cleaned out the copious volumes of dust and other crap, re-fitted them, replenishing the plastic grease that would have been there originally.
Problem 4: Screeching noise during operation
This was going to be a little more difficult to fix. From the sound of it this was likely the bearings in the spindle motor.
Upon removing the spindle motor assembly – a manual spin reveals that the bearings aren’t sounding very healthy. This being a Plextor drive it was fitted with two good quality deep-groove ball bearings as we would expect, but after likely more than a decade of daily punishment even those were completely knackered. Not once in my life have I seen an optical drive so thrashed as to require new bearings!
There are quite a few spindle motors for CD-ROM drives for sale on eBay, but none like this one. Bummer. We’ll have to try hammer those bearings out without destroying the motor in the process.
Without any other obvious ways of doing this, I just went straight at it with an automatic centre punch. After a good dozen or so actuations the spindle separated without any damage.
The bearings used here are 3x7x3mm in size which I was able to purchase couple of replacements of at a cost of just £2.50 each – free shipping.
Fitting the new bearings was easy – I just dabbed a tiny bit of superglue on the brass casing – as it appears there was something gluing the previous bearings in possibly? The spring between the bearings is perhaps there to tension them correctly so perhaps this isn’t necessary.
The process for re-fitting the spindle was similar, pressing from the disc side with a hex spacer this time. This took quite a bit of force.
After a couple of hours of repair, I was surprised to be able to return this very tired old drive to full operation – with it now working as good as it would have done new!
Unfortunately my eBay purchased bearings aren’t amazing quality so the drive is not quite as quiet as I was hoping it’d be, but it is certainly a hell of a lot better. I think I might chuck these out and try find some better ones at some point.
The problems I have shown here were very trivial to fix but this isn’t necessarily always going to be the case. If you have any experience of repairing optical drives – I would be really interested to hear from you what sort of issues they develop, and indeed how to address them!
Recently I was looking around on eBay for an Adaptec SlimSCSI PCMCIA card – for an escapade unrelated to this post, there was of course one there for sale, for a reasonable price, but it included this lump of a CD Burner which I really didn’t want.
I was tempted to just throw it straight in the trash… but…
This happens to be one of the very earliest commercially available 2x (two-spin) units, which likely had a list price of thousands of dollars. I remember hearing about these things in the early to mid 1990s but I never actually saw one with my own eyes.
I knew someone who worked for a company who owned one – he would sneak into the room it lived in after hours to create his own music CDs. He was eventually caught, and sacked. Unfortunately his severance didn’t include the CD Burner.
I didn’t get access to anything like this until around 1999, and that would have been a much more modern 8x4x24 IDE unit which sold at a price affordable to the average person.
Anyway… let’s take a look at this beast.
The first noticeable feature is that it is a “Caddy” drive. These were common during the very early days of CD-ROMs because software CDs in particular cost a lot of money, and most people didn’t have a way to copy them, so paying extra for a caddy was worthwhile to protect the investment. Such CD-ROMs were loaded into a caddy, and left there, reducing the chances of damage to practically zero.
It was common for cheaper CDs to be swapped between caddies as the caddies themselves weren’t especially cheap either. In the end CD-ROMs got cheaper and all the caddy swapping just irritated people. Having a CD Burner eliminated the problem caddies were designed to solve entirely, making it a rather interesting feature for this unit.
Another interesting feature is the SCSI interface. This is because it is an external unit – early CD burners like this were typically standalone because they were insanely expensive, and moved from computer to computer as required. A PCMCIA type attachment as I have shown would have been a popular choice as the unit could be connected to any desired laptop without having to purchase and fit a SCSI adapter to each.
The reason for the choice of SCSI over the more common IDE interface, is that IDE never had a standardised external connection mechanism (although it was possible at a pinch). There was no point in defining one because it was not hot-pluggable, and indeed the consequences of disconnecting drives during operation were generally dire. It was also an un-terminated bus, meaning it would be clobbered by signal reflections if cables were over 30CM or so. Adding additional connectors required for an external interface would have exacerbated the problem significantly.
SCSI on the other hand with hot-swapping built in from the get-go, and with its integral termination mechanism was ideal for this kind of application.
Time to take it apart…
As can be seen from the outside, this is a big unit. We can see it has its own built-in switching power supply down the right hand side. Also as expected a standard form factor 5 1/4″ drive with an interesting bespoke mounting solution. Sony likely also sold this as an internal drive (CDU920S).
Next step is to pull the drive out, and open its top cover.
We are immediately presented with the main PCB, which has a lot of components on it.
And – yup – on the other side as we would expect there is a ridiculous number of chips on it. A modern CD/DVD burner only has two or three chips at most.
Lastly the caddy and optical mechanism. Quite a bit of extra stuff there to deal with that caddy!
Burning a CD with it
I went to the trouble of installing Adaptec Easy CD Creator 4 on an old PC to see if I could make it work. After hours of frustration I gave up. I think it has some hardware issues – as when a disc is inserted it just makes a lot of spinning up / spinning down / clunking noises, doing very little else.
For the past few weeks I’ve been hammering out this project which shows how to re-use old I.T. power supplies for other purposes.
There’s plenty of information about these floating around the internet – so this is not a review, but my first impressions. Let’s unbox and take a look at this 2380-120-60:
If you’re expecting something the usual quality of a Keithley instrument, say, a Source Meter – prepare to be disappointed. In terms of external build quality – I actually found it slightly worse than another Chinese designed & manufactured instrument I own which cost one tenth of the money.
The first issue I noticed is that the tabs on the rear bumper don’t line up with the holes in the metalwork. I’m sure they did in the CAD drawing but unfortunately due to sloppy molding the only way I could get the rear bumper to stay attached is by cutting them down to size a little. Not the kind of thing one expects when purchasing an instrument from a Tier 1 vendor.
Anyway – let’s have a look inside:
The cover isn’t very well formed either – The position of the bends wrapping down to the underside mean it has an extremely tight fit on the inner chassis, suffice to say I had quite a job getting it off. Eventually after a bit of bashing and brute force it succumbed. On my aforementioned £200 Chinese cheapie, that cover glided straight off!
Immediately we can see what the deal is here. That top PCB is 100% identical to the one found in the BK Precision 8601 which its self is designed by ITECH. I’m not going to go to the trouble of dismantling it but from what I can see that bottom PCB is looking pretty damn similar to the 8601 too.
Don’t believe me? Take a look at this:
So… this probably isn’t a Keithley instrument, but some kind of re-branded deal.
A little disappointing – but not a surprise. Given the relentless pressure of Chinese competition on these instruments, I guess western players need to cut every possible cost, and it appears that in this case, the design of the instrument has been outsourced entirely.
There is some good news – some of the gripes in this video i.e. grinding part numbers off chips, and not-particularly-well insulated mains cables – all fixed in this unit.
The uncomfortable feeling I now have – is that this is not a serviceable unit i.e. we can’t buy parts from Keithley like we can for their other products. This is a problem we often get with re-branded products – the marketer cannot provide parts because they don’t manage the life-cycle of the product.
If anyone has gone to the trouble of inquiring with Keithley on this matter I would certainly like to hear from you.
There certainly doesn’t seem to be a downloadable service manual on the Tektronix website.
The good news is perhaps – if parts aren’t obtainable from Keithley, we may be able to get them through the BK Precision / ITECH route instead.
It appears that only the keypad and outer chassis (that’s “shazzy” – if you’re from Australia) differ from the 8601. VFD appears to be identical, and I suspect it’s even running the same firmware too – it does report the same startup message “BIOS Ver1.10” seen on the 8601.
Despite being less than impressed with the physical build – the specification is of course significantly better than my existing £200 unit (which barely has any written specifications at all).
Given the identical spec to the BK Precision 8601 (understandable given it has the same internals) – I’m not quite sure where the value is for that extra £450 asking price.
If I’ve misunderstood anything here – please correct me.