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View Full Version : NEC V20's on ebay...



eccofonic
September 19th, 2017, 03:17 PM
Has anyone bought any of these:

http://www.ebay.com/itm/1pcs-D70108HCZ-16-D70108HCZ-NEC-Encapsulation-DIP-V20HL-V30HL-16-8-16-BIT/251349355121

They're less than $5 shipped.

But coming from China I figure there's always the chance of the chips being counterfeit/bad.

David_M
September 19th, 2017, 04:46 PM
I just ordered one for my XT clone, thanks for the heads up :)

zombienerd
September 19th, 2017, 04:56 PM
Why does the title describe both V20 and V30?

I don't see any options to order the V30 on the page.

bobba84
September 19th, 2017, 05:08 PM
Thanks! Just ordered a few :)

Edit: Strange description on this 80287 (http://www.ebay.com/itm/1pcs-C80287XL-ORIGINAL-Single-inverter-C80287XL-ORIGINAL-DIP-40-NEW-/262917369797?epid=1218158556&hash=item3d3718afc5:g:RlsAAOSw1~JZOkXk)!

Trixter
September 19th, 2017, 06:00 PM
Because the description mentioned both the V20 and V30, I decided to SPIN THE WHEEL and ordered 5 of them. I'm curious what I'll actually get.

SpidersWeb
September 19th, 2017, 06:14 PM
You can't really go wrong at that price. I imagine they're probably legit, but pulled out of random boards from old photocopiers or something.
Capacitors on the other hand, I have a lot from China on special, and yeah... the labels, they mean nothing. But I've had good success with ICs.

evildragon
September 19th, 2017, 06:29 PM
I'm selling V30's, no one's taken me up on the offer, lol.

(Then again, my price was nowhere NEAR like this eBay post---let me know if those CPU's you get actually work for the price, then I'll adjust).

David_M
September 19th, 2017, 11:12 PM
I should have checked AliExpress.com before I ordered.

Five for $5 on there, cant beat a buck each.
https://www.aliexpress.com/item/MAX680CSA-Special-sale/32717986746.html?ws_ab_test=searchweb0_0,searchweb 201602_3_10152_10065_10151_10130_10068_10344_10342 _10343_10340_10341_10307_10137_10060_10131_10155_1 0132_10133_10154_10056_10055_10054_10059_100031_10 099_10338_10339_10103_10102_440_10052_10053_10107_ 10050_10142_10051_10326_10084_10083_10080_10082_10 081_10110_10175_10111_10112_10113_10114_143_10312_ 10313_10314_10078_10079_10073,searchweb201603_2,pp cSwitch_3&btsid=be91177f-2d7f-4869-81d0-3fa849cd193f&algo_expid=86a5d58c-8910-456f-b547-c6ec058c328a-1&algo_pvid=86a5d58c-8910-456f-b547-c6ec058c328a

alecv
September 19th, 2017, 11:15 PM
There is even faster 16MHZ CMOS D70108HCZ-16 (good for overclocking)
http://www.ebay.com/itm/5pcs-D70108HCZ-16-D70108HCZ-NEC-Encapsulation-DIP-V20HL-V30HL-16-8-16-BIT-/261297750463
Good quality, brand new chips.

dJOS
September 19th, 2017, 11:35 PM
Has anyone bought any of these:

http://www.ebay.com/itm/1pcs-D70108HCZ-16-D70108HCZ-NEC-Encapsulation-DIP-V20HL-V30HL-16-8-16-BIT/251349355121

They're less than $5 shipped.

But coming from China I figure there's always the chance of the chips being counterfeit/bad.

I bought 5 from that seller and all of them work fine in my Tandy 1000 EX, I thought I'd have some spares if any where duds. Big thumbs up for me! :cool:

dJOS
September 19th, 2017, 11:37 PM
Because the description mentioned both the V20 and V30, I decided to SPIN THE WHEEL and ordered 5 of them. I'm curious what I'll actually get.

All of mine were marked D70108HCZ and rated at 16mhz, I only ran them at 7.16Mhz so I have no idea if they'd actually run at 16Mhz.

EDIT: mine dont look like remark'd chips either, the printing on them all looks period correct and legit.

konc
September 20th, 2017, 04:49 AM
There is even faster 16MHZ CMOS D70108HCZ-16 (good for overclocking)
http://www.ebay.com/itm/5pcs-D70108HCZ-16-D70108HCZ-NEC-Encapsulation-DIP-V20HL-V30HL-16-8-16-BIT-/261297750463
Good quality, brand new chips.

It's the same seller, just selling 5pcs all together for an unbeatable price. Chips are also the same, 16MHz capable. I've bought 5 from them. In my case chips were exactly the V20 pictured, brand new and all working (at least at 10Mhz)

keenerb
September 25th, 2017, 05:17 AM
It's the same seller, just selling 5pcs all together for an unbeatable price. Chips are also the same, 16MHz capable. I've bought 5 from them. In my case chips were exactly the V20 pictured, brand new and all working (at least at 10Mhz)

Just as a warning I bought several lots of super cheap v20's over the past few months and just over a third of them have survived a basic burnin without freezing.

Nem84
September 25th, 2017, 06:56 AM
I have bought NEC V20 from this seller form my 5160. It works just fine.

Trixter
September 25th, 2017, 09:05 AM
Just as a warning I bought several lots of super cheap v20's over the past few months and just over a third of them have survived a basic burnin without freezing.

That's not clear enough. Did you test all of them and only a third survived, or have you only tested a third of them?

NEC V20s seem to be dirt-cheap-common. What I want are about 5 NEC V30s. I ordered 5 from the ebay auction as they're listed as "both" so I'm hoping I get a mixture.

keenerb
September 25th, 2017, 09:22 AM
That's not clear enough. Did you test all of them and only a third survived, or have you only tested a third of them?

NEC V20s seem to be dirt-cheap-common. What I want are about 5 NEC V30s. I ordered 5 from the ebay auction as they're listed as "both" so I'm hoping I get a mixture.

I missed that this was for v30's.

Also, one-third of them FAILED testing. I bought twelve total in three batches from different sellers on Ebay, and five would lock up overnight running a cpu-intensive load, despite being downrated to 8mhz...

Trixter
September 25th, 2017, 09:43 AM
Whoa, I'm glad I asked! Testing will be required, then.

The forum thread is for NEC V20s. The ebay auction everyone is linking to lists both V20 and V30 in the title, hence my previous comment.

tempest
September 27th, 2017, 10:56 AM
I saw these as well but I'm a bit hesitant to buy anything from China these days. Maybe I can get an extra one off someone here if they test alright.

eccofonic
October 2nd, 2017, 10:03 AM
The one I bought seems to work fine in my 5150 (has 8087 installed).

Topbench (Oldskool Benchmark) says it's 1.5x faster than a normal 5150 and IDs it as NEC V20 4.77mhz

Funny how older system info programs are all over the map in terms of what the speed/mhz is.

Syschk thinks its V20 18mhz but benchmarks throughput at 2.72mhz (relative to an AT maybe?).

Norton SysInfo thinks its a V20 8mhz. With speed rating at 1.0.

The command line version of Norton SysInfo just says "NEC V20" with computing index of 1.8

Maxum Processor Clock Speed Test says 18mhz !

Landmark Speed Test 2.0 says "NEC V20/V30" with 3.185mhz CPU clock (!) performing like a 2.13mhz AT PC (FPU is 6.04mhz)

"MIPS" program from Chips & Technologies in 1986 says relative performance to IBM PC 4.77mhz:

1.18 on general instructions, 1.92 on integer instructions, 1.13 memory, 2.19 register, 1.09 register to memory, 1.33 overall

Trixter
October 3rd, 2017, 07:30 AM
Funny how older system info programs are all over the map in terms of what the speed/mhz is.

Now you know why I wrote TOPBENCH. The synthetic "Score" number TOPBENCH produces is just that -- synthetic -- which you can use to compare relative speed across systems operating in 16-bit real mode. If system A has a Score of "4" and system B has a Score of "8", then system B is twice as fast. Simple.

Trying to exactly identify the "MHz" of a CPU and then use it as your comparison metric just led to confusion back then. I never understood the point of Landmark using "6 MHZ AT speed" as a metric.

David_M
October 9th, 2017, 07:57 PM
Now that a bunch of us have fitted a V20 in our XT's (Mine works fine).... who has some software that makes use of its 8080 features?

Chuck(G)
October 9th, 2017, 08:14 PM
Early versions of 22Nice work well, and there was a package called CPMulator, that I uploaded for a curious member. I don't recall if UniDOS could make use of the feature. I removed the 22Nice V20 support as even a moderately fast PC AT would run just as fast in software emulation without the little V20 bugs.

Bottom line: You can use the facility (also present in the V30, V40 and V50, as well as the V33) to run 8080 CP/M.

konc
October 9th, 2017, 11:51 PM
Now that a bunch of us have fitted a V20 in our XT's (Mine works fine).... who has some software that makes use of its 8080 features?

I find more useful the 80186 instructions that allow you to run a couple of programs officially requiring a 286, but don't use protected mode

Xacalite
October 10th, 2017, 04:37 AM
CPeMulator can be found here - http://oldcomputers.dyndns.org/public/pub/mirror/os2site/sw/dec/emulators/v2080j88.zip

David_M
October 10th, 2017, 06:02 AM
I find more useful the 80186 instructions that allow you to run a couple of programs officially requiring a 286, but don't use protected mode

Back in the day I fitted my XT clone with a V20 because it was a shade faster but I never used the enhanced features. I only put one in my current XT for nostalgia sake along with an 8087 I have on order.
I've also just restored an 80286 and an IBM 80486slc-50 based system to add the the growing collection. I currently have 12 PC's ranging from the XT up to a quad core cpu. As well as a TRS-80 clone and Apple 2 machines. I don't use them for anything but i do like them to be fully functional.

Chuck(G)
October 10th, 2017, 08:52 AM
Most think of a V20 as an 8088 with some 80186 instructions and 8080 emulation. But it was more than that.

For example, it's interesting that I've never seen a package that used the V20 BCD instruction set (I don't mean DAA/DAS/AAA/AAS/AAM). ADD4S/SUB4S/CMP4S can do BCD operations up to 254 digits.

Or the ROR4/ROL4 instructions that rotate only the right- or left- nibble of a byte.

Or the TEST1/SET1/CLR1/NOT1 bit operations, which operate on a specific bit (addressed by bit ordinal) of a byte or word.

There's also a second set of external processor escape codes, but I'm not aware of any chips manufactured to support them.

It's interesting that the Z80 additions to the 8080 instruction set came to dominate the 8-bit x80 scene, while it's hard to find any code that used the V-series additions.

David_M
October 10th, 2017, 12:07 PM
Back in the day I really wanted to make use of those more powerful instructions, I even setup some macro's to support them. Ultimately I never used them because they were just not common enough and using them would lock out the majority of the market.

vwestlife
October 10th, 2017, 12:52 PM
I put a V20 or V30 in any XT-class system with a socketed CPU, so I can run DOS real-mode programs that would otherwise require at least a 286, such as the Windows 95+ version of DOS EDIT, the Iomega Zip drive "GUEST" driver, the 286 version of TanTrakr on my Tandy 1000SL, and several other utilities.

dJOS
October 10th, 2017, 02:19 PM
I put a V20 or V30 in any XT-class system with a socketed CPU, so I can run DOS real-mode programs that would otherwise require at least a 286, such as the Windows 95+ version of DOS EDIT, the Iomega Zip drive "GUEST" driver, the 286 version of TanTrakr on my Tandy 1000SL, and several other utilities.

I think the best "modern" use for a V20 is the speed up you get from using the 286/V20+ FW for XT-IDE HDD Controllers instead of the pure 8088/86 FW.

AlexC
October 10th, 2017, 09:48 PM
I think the best "modern" use for a V20 is the speed up you get from using the 286/V20+ FW for XT-IDE HDD Controllers instead of the pure 8088/86 FW.

Definitely. This makes a huge performance difference. I was quite amazed when I first used the V20+ XUB in my XT-class machine. Roughly 20% performance improvement with a CF card.

David_M
October 10th, 2017, 11:10 PM
Definitely. This makes a huge performance difference. I was quite amazed when I first used the V20+ XUB in my XT-class machine. Roughly 20% performance improvement with a CF card.

I'm using an XT-IDE controller.. must try it now.

dJOS
October 10th, 2017, 11:28 PM
Definitely. This makes a huge performance difference. I was quite amazed when I first used the V20+ XUB in my XT-class machine. Roughly 20% performance improvement with a CF card.

My little Tandy 1000 EX with a 4GB Seagate ST1 microdrive flies along with the "XTP" firmware getting close to 1/2 MB/s transfer speeds. According to CheckIt that's 4.88 times faster than a stock IBM XT with HDD back in the day.

David_M
October 11th, 2017, 02:24 AM
Definitely. This makes a huge performance difference. I was quite amazed when I first used the V20+ XUB in my XT-class machine. Roughly 20% performance improvement with a CF card.

Interesting.. first attempt to reflash killed the flash chip. So after replacing the flash rom I benchmarked the standard 8088 version and got 250 K/s. Reprogrammed with the 80186 version and got 180 K/s.
Maybe it doesnt work so well on the Rev 1 cards.

Edit: I did a second run and got 324 K/s, maybe the turbo button is a bit flakey

dJOS
October 11th, 2017, 02:31 AM
Interesting.. first attempt to reflash killed the flash chip. So after replacing the flash rom I benchmarked the standard 8088 version and got 250 K/s. Reprogrammed with the 80186 version and got 180 K/s.
Maybe it doesnt work so well on the Rev 1 cards.

Are you using BIU offload too?

This is mine using a generic c.f. flash card.

https://i.imgur.com/jnQZfpq.jpg

AlexC
October 11th, 2017, 02:32 AM
Interesting.. first attempt to reflash killed the flash chip. So after replacing the flash rom I benchmarked the standard 8088 version and got 250 K/s. Reprogrammed with the 80186 version and got 180 K/s.
Maybe it doesnt work so well on the Rev 1 cards.

I did my testing using a standard 16-bit IDE adapter in an 8-bit slot, booting the XUB via a floppy disk (there's an extensive thread about that method on here somewhere). Made it easy to swap and compare. I wrote a self-timing batch file that did several minutes of file copying, etc.

I'd actually set it all up to compare the performance of different numbers of config.sys buffers, but then I tried the V20+ XUB out of curiosity and was amazed by the difference.

Malc
October 11th, 2017, 02:43 AM
I noticed the speed difference in my 5160 with XUB and 16-bit IDE card when i replaced the 8088 with a Sony V20, Perhaps the R1 cards need the 'Chuck' Mod, I never did the mod to my R1 cards.

David_M
October 11th, 2017, 02:46 AM
Are you using BIU offload too?

This is mine using a generic c.f. flash card.



That option isn't available for a rev1 card

dJOS
October 11th, 2017, 03:06 AM
That option isn't available for a rev1 card

Ah ok, I assumed that because BIU is a feature of the x86 chipset, not the IDE controller, it was only BIOS support that was needed. In any case the XTP FW +V20 (im using r580) should produce a noticeable speed bump. My 7Mhz 1000 EX went from 284KB/s to almost 500KB/s with no other change (In CheckIT).

Krille
October 11th, 2017, 04:44 AM
Most think of a V20 as an 8088 with some 80186 instructions and 8080 emulation. But it was more than that.

For example, it's interesting that I've never seen a package that used the V20 BCD instruction set (I don't mean DAA/DAS/AAA/AAS/AAM). ADD4S/SUB4S/CMP4S can do BCD operations up to 254 digits.

Or the ROR4/ROL4 instructions that rotate only the right- or left- nibble of a byte.

Or the TEST1/SET1/CLR1/NOT1 bit operations, which operate on a specific bit (addressed by bit ordinal) of a byte or word.

I've actually had the idea to use the NEC V-specific features (8080 emulation and/or the extra instructions) for optimizing XTIDE Universal BIOS. I've yet to find any code where the benefit is obvious but that's probably due to my lack of understanding of the instructions. If someone can provide examples of code where replacing Intel code with NEC code is beneficial then I'm all ears. Note, the only documentation I have is 86BUGS.LST from RBIL and I have no way to test code since I don't have the hardware.

Chuck(G)
October 11th, 2017, 09:51 AM
About all I could see the special V20 instructions being useful for is decimal arithmetic, which was more common back in the day. For a time, using decimal floating point in spreadsheets was considered to be a big plus.

alecv
October 13th, 2017, 12:01 AM
AFAIK, some NEC V20 instructions binary codes conflict with 386+. Fortunately most useful POPA/PUSHA and INSx/OUTx use the same code as "official" Intel 186+ .

Trixter
October 13th, 2017, 11:27 AM
I've actually had the idea to use the NEC V-specific features (8080 emulation and/or the extra instructions) for optimizing XTIDE Universal BIOS. I've yet to find any code where the benefit is obvious but that's probably due to my lack of understanding of the instructions.

The ability to rotate/shift nybbles instead of the entire byte is useful. Also the ability to set/clear bitfields. http://datasheets.chipdb.org/NEC/V20-V30/U11301EJ5V0UMJ1.PDF has info, except the mnemonics are different (likely to avoid friction with Intel) so you have to find the actual opcodes in the indexes in the back.

Chuck(G)
October 13th, 2017, 11:42 AM
My reference is "uPD70108/70116 Low-Power CMOS Microprocessors" User Manual, August, 1985 Stock 500530

Somewhere around 200 pp. I picked it up back in the day from NEC USA (Natick, MA). I also have a few MicroNotes.

There's also a decent rundown in NEC's "16-bit V-Series Microprocessor Handbook" from 1991.

alecv
October 13th, 2017, 12:41 PM
JFYI:
http://phg.chat.ru/opcode.txt
It seems this is compilation from the Ralf Brown's Interrsupt List.
Search "NEC" for V-xx specific information.
"TABLE00" - single byte opcodes
"TABLE 01" - 0F XX opcodes

Krille
November 12th, 2017, 12:07 PM
I've added a new define to XUB: 'USE_NEC_V' which enables use of the extra instructions, hence it can *only* be used on NEC V20/V30 processors. I've only implemented the CLR1 instruction because it's the only one I've found useful so far (in the context of XUB). It's only used once in MODULE_IRQ which normally isn't part of XT-builds so it's basically pointless. Still, it saves a whopping 3 bytes when used. :)

Hopefully I'll find more uses for the extra instructions in the future.