Path: chonsp.franklin.ch!not-for-mail From: Neil Franklin Newsgroups: alt.folklore.computers Subject: NEC V20/20/40/50/60, was Re: First OS? Date: 07 Feb 2001 20:47:47 +0100 Organization: My own Private Self Lines: 49 Message-ID: <6un1byuvfg.fsf_-_@chonsp.franklin.ch> References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> NNTP-Posting-Host: chonsp.franklin.ch X-Trace: chonsp.franklin.ch 981575271 810 10.0.3.2 (7 Feb 2001 19:47:51 GMT) X-Complaints-To: news@chonsp.franklin.ch NNTP-Posting-Date: 7 Feb 2001 19:47:51 GMT X-Newsreader: Gnus v5.7/Emacs 20.4 Xref: chonsp.franklin.ch alt.folklore.computers:75086 glass2@glass2.lexington.ibm.com writes: > In <3A8176B6.6EC1@virgin.net>, Alec writes: > >Charlie Gibbs wrote: > >> > >> How about the NEC V20? > >> > >As you mentioned it there was also a V30 & V40 as well. > > The great thing about the V20 was that it was pin compatible with the > 8088, so it was a simple matter to unplug the 8088 from a XT, and > plug in the V20. It usually resulted in a speed up of between 7 and 50 > percent. Yes. > However, if I remember correctly, the V20 had a slight timing > difference such that substituting a 5 MHz rated V20 for a 5 MHz rated 8088 > violated one of the clock specifications, although it usually worked. The 8086/8088 used an 2/1 phase clock, the V20/V30 needed an 1/1 phase. Best done by replacing the 8284A clock generator with an uPD71011, side effect was 7.16MHz for the CPU. > I don't remember that the V30 and V40 chips were direct replacements > for Intel chips, or, if they were, they were for Intel chips not usually used > in PC equipment (Could they have been replacements for the 80186 and 80188, > which VERY few companies used in their PC, possibly excepting Tandy's Radio > Shack computers.). V20: 8088 V30: 8086 V40: 80188 (AFAIK) V50: 80186 (AFAIK) V60: possibly 286 instruction set, but definitely not direct replacement > The neat thing about the NEC V20 was that it had an emulation mode where it > would emulate a previous generation processor. Did it emulate the 8080? It's > been way too long for me to remember. IIRC it did an full Z80. -- Neil Franklin, neil@franklin.ch.remove http://neil.franklin.ch/ Hacker, Unix Guru, El Eng FH/BSc, Sysadmin, Roleplayer, LARPer, Mystic ###### From: jmaynard@thebrain.conmicro.cx (Jay Maynard) Newsgroups: alt.folklore.computers Subject: Re: NEC V20/20/40/50/60, was Re: First OS? Date: 8 Feb 2001 01:23:16 GMT Organization: Neosoft (using Airnews.net!) Lines: 15 Message-ID: <9F3CABAD712656F2.96D6DDF1809DFC95.04CB354C5899CF23@lp.airnews.net> X-Orig-Message-ID: References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> <6un1byuvfg.fsf_-_@chonsp.franklin.ch> Reply-To: jmaynard@conmicro.cx Abuse-Reports-To: abuse at airmail.net to report improper postings NNTP-Proxy-Relay: library1-aux.airnews.net NNTP-Posting-Time: Wed Feb 7 19:23:16 2001 NNTP-Posting-Host: !b>ge1k-YA!8+VE (Encoded at Airnews!) User-Agent: slrn/0.9.5.4 (UNIX) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!Amsterdam.Infonet!News.Amsterdam.UnisourceCS!skynet.be!news.stealth.net!24.30.200.2.MISMATCH!news-east.rr.com!cyclone-west.rr.com!news.rr.com!news-west.rr.com!cabal10.airnews.net!news.airnews.net!cabal14.airnews.net!news.airnews.net!cabal1.airnews.net!news-f.iadfw.net!jmaynard Xref: chonsp.franklin.ch alt.folklore.computers:75116 On 07 Feb 2001 20:47:47 +0100, Neil Franklin wrote: >The 8086/8088 used an 2/1 phase clock, the V20/V30 needed an 1/1 >phase. Best done by replacing the 8284A clock generator with an >uPD71011, side effect was 7.16MHz for the CPU. How'd plugging a V20 in in place of an 8088 and making no other changes work, then? >> The neat thing about the NEC V20 was that it had an emulation mode where it >> would emulate a previous generation processor. Did it emulate the 8080? It's >> been way too long for me to remember. >IIRC it did an full Z80. I think so, too. NEC was a licensed second source for the Z-80, so this would have been simple (comparatively). ###### From: Giles Todd Newsgroups: alt.folklore.computers Subject: Re: NEC V20/20/40/50/60, was Re: First OS? Date: Thu, 08 Feb 2001 02:32:45 +0100 Organization: None Message-ID: Reply-To: gt@at-dot.org References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> <6un1byuvfg.fsf_-_@chonsp.franklin.ch> <3A82572E.11A7@virgin.net> X-Newsreader: Forte Agent 1.8/32.548 X-No-Archive: yes MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Complaints-To: newsabuse@supernews.com Lines: 34 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!newsfeeds.belnet.be!news.belnet.be!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.stanford.edu!sn-xit-01!sn-post-01!supernews.com!news.supernews.com!lart!nobody Xref: chonsp.franklin.ch alt.folklore.computers:75257 On Thu, 08 Feb 2001 00:22:06 -0800, Alec wrote: > My understanding of the V40 was that it was an 8088 equivalent with > other functions added into the chip, possibly serial port function. I > still have an Olivetti PC1 that used this processor and possibly as a > result has a non standard serial port and a mouse port similar to that > used on the Amstrad 1512/1640. From memory, the V40 was a sort of "soft" 80188. It had all the devices which an 80188 had (with one exception which I will get to later), with the advantage that the I/O ports could be remapped. In practice, this resulted in the ports being mapped to the same places as they existed on the IBM PC. The one exception was the DMA device. It wasn't the one used in the PC. But NEC published an application note with a software hack demonstrating how, with the aid of NMI, you could redirect DMA interrupts to a routine which would examine the IBM PC DMA instruction on the stack, translate it to the equivalent V40 DMA instruction and then do the business (I have long forgotten the numbers/names of the DMA chips used in the original PC and the V40). Anyway, with a little BIOS hacking in the FDC routine to make it rewrite the NMI vector every time it was called (it turned out that "debug" from MS-DOS 3.3 rewrote NMI too which was something of a pain when debugging until we worked out why the FDC stopped working every time we looked at a problem), it worked as advertised. Sufficiently well enough to run a 1987 version of Lotus 123 from floppies anyway. Which wasn't bad for a late 1980s EPOS terminal. Giles. -- There is no room in war for pique, spite, or rancour. ###### Message-ID: <3A82572E.11A7@virgin.net> From: Alec X-Mailer: Mozilla 3.01C-VN712-000 (Win16; I) MIME-Version: 1.0 Newsgroups: alt.folklore.computers Subject: Re: NEC V20/20/40/50/60, was Re: First OS? References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> <6un1byuvfg.fsf_-_@chonsp.franklin.ch> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 16 Date: Thu, 08 Feb 2001 00:22:06 -0800 NNTP-Posting-Host: 194.168.70.56 X-Complaints-To: abuse@virgin.net X-Trace: news2-win.server.ntlworld.com 981591937 194.168.70.56 (Thu, 08 Feb 2001 00:25:37 GMT) NNTP-Posting-Date: Thu, 08 Feb 2001 00:25:37 GMT Organization: Virgin Net Usenet Service Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!news-fra1.dfn.de!news.tele.dk!212.43.194.69!fr.clara.net!heighliner.fr.clara.net!grolier!btnet-peer0!btnet!news5-gui.server.ntli.net!ntli.net!news2-win.server.ntlworld.com.POSTED!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:75281 Neil Franklin wrote: > > V20: 8088 > V30: 8086 > V40: 80188 (AFAIK) > V50: 80186 (AFAIK) > V60: possibly 286 instruction set, but definitely not direct replacement > My understanding of the V40 was that it was an 8088 equivalent with other functions added into the chip, possibly serial port function. I still have an Olivetti PC1 that used this processor and possibly as a result has a non standard serial port and a mouse port similar to that used on the Amstrad 1512/1640. Alec ###### Message-ID: <3A82AE81.2A4D@virgin.net> From: Alec X-Mailer: Mozilla 3.01C-VN712-000 (Win16; I) MIME-Version: 1.0 Newsgroups: alt.folklore.computers Subject: Re: NEC V20/20/40/50/60, was Re: First OS? References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> <6un1byuvfg.fsf_-_@chonsp.franklin.ch> <3A82572E.11A7@virgin.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 29 Date: Thu, 08 Feb 2001 06:34:41 -0800 NNTP-Posting-Host: 194.168.64.147 X-Complaints-To: abuse@virgin.net X-Trace: news6-win.server.ntlworld.com 981614358 194.168.64.147 (Thu, 08 Feb 2001 06:39:18 GMT) NNTP-Posting-Date: Thu, 08 Feb 2001 06:39:18 GMT Organization: Virgin Net Usenet Service Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!newsfeeds.belnet.be!news.belnet.be!btnet-peer1!btnet-peer0!btnet!news5-gui.server.ntli.net!ntli.net!news6-win.server.ntlworld.com.POSTED!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:75286 Giles Todd wrote: > > The one exception was the DMA device. It wasn't the one used in the > PC. But NEC published an application note with a software hack > demonstrating how, with the aid of NMI, you could redirect DMA > interrupts to a routine which would examine the IBM PC DMA instruction > on the stack, translate it to the equivalent V40 DMA instruction and > then do the business. > Could this have something to do with one real problem with the PC1 then. Adding a HDD (except the Olivetti one) was a real pain. If you used the default BIOS setting (C8000?) on the controller card the machine hung on boot-up. If this was changed it would start up o.k. but would not boot from the HDD, only floppy, then quite happily use the HDD. By trial and error it was found that if the default setting was used but the HDD not powered up the till mid way through the boot sequence the PC1 would start up, report HDD not ready then boot from it. I never did get my head round this one but it worked! The serial port was also useless as one line normally set high was set low I seem to recall. Never tried a mouse on it myself having heared stories of mice so connected getting to hot to hold and not working anyway! The only reason I could see that Olivetti would use this processor is to allow the PC1 to be made so compact. Alec. ###### From: timothy.mccaffrey@spam2filter.unisys.com.takethisoff (Tim McCaffrey) Newsgroups: alt.folklore.computers Subject: Re: NEC V20/20/40/50/60, was Re: First OS? Date: 8 Feb 2001 18:45:08 GMT Organization: A series networking Lines: 34 Message-ID: <95upfk$hkm$1@mail.pl.unisys.com> References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> <6un1byuvfg.fsf_-_@chonsp.franklin.ch> <9F3CABAD712656F2.96D6DDF1809DFC95.04CB354C5899CF23@lp.airnews.net> NNTP-Posting-Host: 192.63.212.151 X-Newsreader: WinVN 0.99.9 (Released Version) (x86 32bit) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!enews.sgi.com!eanews1.unisys.com!plnews.pl.unisys.com!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:75209 In article <9F3CABAD712656F2.96D6DDF1809DFC95.04CB354C5899CF23@lp.airnews.net>, Jay Maynard says... > >On 07 Feb 2001 20:47:47 +0100, Neil Franklin wrote: >>The 8086/8088 used an 2/1 phase clock, the V20/V30 needed an 1/1 >>phase. Best done by replacing the 8284A clock generator with an >>uPD71011, side effect was 7.16MHz for the CPU. > >How'd plugging a V20 in in place of an 8088 and making no other changes >work, then? > NEC modified the later versions to tolerate the Intel clock chip. >>> The neat thing about the NEC V20 was that it had an emulation mode where it >>> would emulate a previous generation processor. Did it emulate the 8080? It' >s >>> been way too long for me to remember. >>IIRC it did an full Z80. > >I think so, too. NEC was a licensed second source for the Z-80, so this >would have been simple (comparatively). Sorry, no. The V20/V30/etc emulated an 8080. The Z-80 actually has too many registers to emulate easily within the 8088's registers. I wished they had implemented an unimplemented instruction exception so a full Z80 emulation could have been done, but no such luck. - Tim ###### Sender: eric@ruckus.brouhaha.com From: Eric Smith Newsgroups: alt.folklore.computers Subject: Re: NEC V20/20/40/50/60, was Re: First OS? References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> <6un1byuvfg.fsf_-_@chonsp.franklin.ch> X-Disclaimer: Everything I write is false. Organization: Eric Conspiracy Secret Labs X-Eric-Conspiracy: There is no conspiracy. Date: 08 Feb 2001 16:17:07 -0800 Message-ID: Lines: 7 User-Agent: Gnus/5.0807 (Gnus v5.8.7) Emacs/20.7 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii NNTP-Posting-Host: ruckus.brouhaha.com X-Trace: 8 Feb 2001 16:17:08 -0800, ruckus.brouhaha.com Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!news.maxwell.syr.edu!newsfeed.stanford.edu!news.kjsl.com!news.spies.com!ruckus.brouhaha.com Xref: chonsp.franklin.ch alt.folklore.computers:75234 >> The neat thing about the NEC V20 was that it had an emulation mode >> where it would emulate a previous generation processor. Did it >> emulate the 8080? It's been way too long for me to remember. > IIRC it did an full Z80. Unfortunately not. Just 8080. ###### Sender: eric@ruckus.brouhaha.com From: Eric Smith Newsgroups: alt.folklore.computers Subject: Re: NEC V20/20/40/50/60, was Re: First OS? References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> <6un1byuvfg.fsf_-_@chonsp.franklin.ch> <9F3CABAD712656F2.96D6DDF1809DFC95.04CB354C5899CF23@lp.airnews.net> X-Disclaimer: Everything I write is false. Organization: Eric Conspiracy Secret Labs X-Eric-Conspiracy: There is no conspiracy. Date: 08 Feb 2001 16:27:44 -0800 Message-ID: Lines: 10 User-Agent: Gnus/5.0807 (Gnus v5.8.7) Emacs/20.7 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii NNTP-Posting-Host: ruckus.brouhaha.com X-Trace: 8 Feb 2001 16:27:45 -0800, ruckus.brouhaha.com Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!news.tesion.net!news.belwue.de!news-stu1.dfn.de!news-koe1.dfn.de!news-was.dfn.de!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.stanford.edu!news.kjsl.com!news.spies.com!ruckus.brouhaha.com Xref: chonsp.franklin.ch alt.folklore.computers:75235 >>> The neat thing about the NEC V20 was that it had an emulation mode >>> where it would emulate a previous generation processor. Did it >>> emulate the 8080? It's been way too long for me to remember. >> IIRC it did an full Z80. > I think so, too. NEC was a licensed second source for the Z-80, so this > would have been simple (comparatively). Unfortunatly not. The 8080 had a subset of the 8086/8088 register set, the Z-80 does not. They probably didn't think that the extra die area and development time would be worthwhile. ###### From: Bruce Tomlin Newsgroups: alt.folklore.computers Subject: Re: NEC V20/20/40/50/60, was Re: First OS? Date: Fri, 09 Feb 2001 08:01:21 -0600 Organization: San Antonio, TX Lines: 13 Message-ID: References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> <6un1byuvfg.fsf_-_@chonsp.franklin.ch> <9F3CABAD712656F2.96D6DDF1809DFC95.04CB354C5899CF23@lp.airnews.net> <95upfk$hkm$1@mail.pl.unisys.com> NNTP-Posting-Host: nukunuku.fanboy.net X-Trace: news.jump.net 981727271 27784 207.8.48.140 (9 Feb 2001 14:01:11 GMT) X-Complaints-To: abuse@jump.net NNTP-Posting-Date: Fri, 9 Feb 2001 14:01:11 +0000 (UTC) User-Agent: MT-NewsWatcher/3.0 (PPC) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!news.tesion.net!news.belwue.de!news-stu1.dfn.de!news-koe1.dfn.de!news-fra1.dfn.de!news.tele.dk!205.231.236.10!newspeer.monmouth.com!news-feeds.jump.net!news.jump.net!bruceNS+usenet5 Xref: chonsp.franklin.ch alt.folklore.computers:75292 In article <95upfk$hkm$1@mail.pl.unisys.com>, timothy.mccaffrey@spam2filter.unisys.com.takethisoff (Tim McCaffrey) wrote: > Sorry, no. The V20/V30/etc emulated an 8080. The Z-80 actually has too > many > registers to emulate easily within the 8088's registers. I wished they had > implemented an unimplemented instruction exception so a full Z80 emulation > could have been done, but no such luck. I think they should have at least done the Z-80's JR instructions. Those were the only Z-80 instructions that Turbo Pascal used, and it would have made CP/M emulation worth the trouble for me when I had a V-30 in a Tandy 1000 TL. ###### Newsgroups: alt.folklore.computers From: @mb.sympatico.ca Subject: Re: NEC V20/20/40/50/60, was Re: First OS? Reply-To: wtshyman@mb.sympatico.ca Organization: No Unsolicited Commercial E-Mail, Please ! References: <20010128184525.22610.00002177@ng-cp1.aol.com> <95mo4r$73e@nnrp3.farm.idt.net> <8qfu7tgqbd9j0rdl11d9iqeourujtrv02l@4ax.com> <3A7FA80C.853761E0@ev1.net> <2001Feb6.121021.8021@lorelei.approve.se> <491.437T2538T6726291@sky.bus.com> <3A8176B6.6EC1@virgin.net> <95rm8h$l44$2@ausnews.austin.ibm.com> <6un1byuvfg.fsf_-_@chonsp.franklin.ch> <9F3CABAD712656F2.96D6DDF1809DFC95.04CB354C5899CF23@lp.airnews.net> X-Newsreader: IBM NewsReader/2 2.0 Lines: 26 Message-ID: Date: Fri, 09 Feb 2001 16:54:07 GMT NNTP-Posting-Host: 205.200.55.112 X-Complaints-To: admin@mts.net X-Trace: news1.mts.net 981737647 205.200.55.112 (Fri, 09 Feb 2001 10:54:07 CST) NNTP-Posting-Date: Fri, 09 Feb 2001 10:54:07 CST Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!news.tesion.net!news.belwue.de!informatik.tu-muenchen.de!lmu.de!uni-erlangen.de!news-nue1.dfn.de!news-lei1.dfn.de!news-was.dfn.de!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.skycache.com!Cidera!portc03.blue.aol.com!newsfeed.cwix.com!news-in.mts.net!news1.mts.net.POSTED!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:75168 In <9F3CABAD712656F2.96D6DDF1809DFC95.04CB354C5899CF23@lp.airnews.net>, jmaynard@thebrain.conmicro.cx (Jay Maynard) writes: >On 07 Feb 2001 20:47:47 +0100, Neil Franklin wrote: >>The 8086/8088 used an 2/1 phase clock, the V20/V30 needed an 1/1 >>phase. Best done by replacing the 8284A clock generator with an >>uPD71011, side effect was 7.16MHz for the CPU. > >How'd plugging a V20 in in place of an 8088 and making no other changes >work, then? > >>> The neat thing about the NEC V20 was that it had an emulation mode where it >>> would emulate a previous generation processor. Did it emulate the 8080? It's >>> been way too long for me to remember. >>IIRC it did an full Z80. > >I think so, too. NEC was a licensed second source for the Z-80, so this >would have been simple (comparatively). I don't have a V20 manual but back in my CP/M user group days the use of the V20 was discussed quite heavily; the only drawback we could find is that it could not support ZCPR ( a console command processor replacement that had many fine features including paths!) since the V20 did not have the Z80 opcodes or registers. Bill