From: Phil Hays Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Sun, 26 Sep 1999 23:08:13 -0700 Organization: Real email is pdhays at same service Lines: 42 Message-ID: <37EF09CD.9188187C@sprynet.com> References: <7s56tp$cmi$1@info.cs.uofs.edu> <37ed7239.760831227@192.168.0.1> <7sfutm$1gp$2@info.cs.uofs.edu> <37EBB1CA.F30684FA@egg.chips.and.spam.com> <37ED9D43.3CD03009@sprynet.com> <37EE1D6D.B76C3328@egg.chips.and.spam.com> NNTP-Posting-Host: a5.79.20.54 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Server-Date: 27 Sep 1999 06:03:52 GMT X-Mailer: Mozilla 4.08 [en] (WinNT; U) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!news.datacomm.ch!newscore.gigabell.net!newscore.ipf.de!newsfeed2.news.nl.uu.net!sun4nl!remarQ-easT!supernews.com!remarQ.com!news.mindspring.net!firehose.mindspring.com!not-for-mail fungus wrote: > On a single scan line the Z80 could only move about 16 bytes > of data so there's no way it could look up characters in ROM > or anythign like that. The Z80 wasn't moving any data: while in display, it was executing NOPs. Think of it as only an address counter. The system ASIC (or PAL or a pile of TTL) was receiving the display list out of RAM, forcing a NOP into the CPU, sending a character address (the character to display concatenated with the line being scanned) to the system ROM (part of which was a character generation table, reading the ROM data into a shift register, and then shipping the bits off one at a time. Resisters were used to allow the asic to force out the NOP at the correct time, and to force out an address to just the ROM. All of this while the CPU was executing a NOP. Repeat for each character on a line. At the end of a scan line is a few extra cycles to get the address to the correct value for the next scan line. I don't recall ever learning the exact hacks used. My vague memory is something like an interrupt and some carefully timed instructions that did nothing other than to start the display list at the correct point and at the correct clock cycle. This is all from fuzzy memory, somewhat updated by looking at various and sundry web pages tonight. The earlier reply didn't mention the fetch from the character table in ROM for the simple reason I had forgot it. And there is/was only one byte needed to end the display list: a return instruction, which both took the asic out of display mode and returned the CPU to executing a real program. I am surprised to see all the interest in the ZX80/ZX81/Timex_1000/Timex_1500/Timex_2000 computers on the web. I enjoyed working on the asic for the Timex 1500, and on the asic for the Timex 2000 (and I feared both had sank without a trace). -- Phil Hays "Irritatingly, science claims to set limits on what we can do, even in principle." Carl Sagan ###### From: "Peter Pachla" Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Mon, 27 Sep 1999 00:58:31 +0100 Organization: WinterMute Lines: 29 Message-ID: <7smeq0$g3m$3@gxsn.com> References: <7s56tp$cmi$1@info.cs.uofs.edu> <37ed7239.760831227@192.168.0.1> <7sfutm$1gp$2@info.cs.uofs.edu> <37EBB1CA.F30684FA@egg.chips.and.spam.com> <37ED9D43.3CD03009@sprynet.com> <37EE1D6D.B76C3328@egg.chips.and.spam.com> Reply-To: "Peter Pachla" NNTP-Posting-Host: 195.147.232.45 X-Trace: 938393216 1NNUCNF1GE82DC393C gxsn.com X-Complaints-To: abuse@gxsn.com X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2014.211 X-Mimeole: Produced By Microsoft MimeOLE V5.00.2014.211 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!enews.sgi.com!paloalto-snf1.gtei.net!news.gtei.net!newsfeed.stanford.edu!remarQ73!supernews.com!remarQ.com!remarQ69!gxsn.com!not-for-mail Hi, > The only plausible way I can think of to make the display work > would be that that the PAL needed to have each line of chars > loaded into the PAL, and from there it could decode the chars > all by itself (looking them up in the ROM), producing 8 lines > of pixels before the next row was needed. The ULA contains no RAM etc for line buffering. When I got a 16K RAM pack for my '81 I designed and built a programmable character generator using the internal 1K of RAM. Memory is a bit hazy here now, but as I recall the ULA would enable ROM and read character data from it row by row across the scanline. TTFN - Pete. -- Spam deflector in effect - it's obvious! "Very funny Scotty, now beam down my trousers!" - J.T.Kirk Hardware & Software Engineer. Sound Engineer. Collector of Arcade Machines, Games Consoles & Obsolete Computers (esp DEC) -- ###### From: don@news.daedalus.co.nz (Don Stokes) Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: 27 Sep 1999 07:54:54 GMT Organization: Daedalus Consulting Lines: 22 Message-ID: <938454854.402621@shelley.paradise.net.nz> References: <37ED9D43.3CD03009@sprynet.com> <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> NNTP-Posting-Host: shelley.paradise.net.nz X-Trace: titan.xtra.co.nz 938418894 8880660 203.96.152.26 (27 Sep 1999 07:54:54 GMT) X-Complaints-To: abuse@xtra.co.nz NNTP-Posting-Date: 27 Sep 1999 07:54:54 GMT Cache-Post-Path: shelley.paradise.net.nz!unknown@203-96-144-16.cable.paradise.net.nz X-Cache: nntpcache 2.3.3b4 (see http://www.nntpcache.org/) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!isdnet!remarQ-easT!supernews.com!remarQ.com!news.maxwell.syr.edu!newsfeed1.earthlink.net!lsanca1-snf1!news.gtei.net!news.netgate.net.nz!news.xtra.co.nz!don Peter Pachla wrote: >When I got a 16K RAM pack for my '81 I designed and built a programmable >character generator using the internal 1K of RAM. Memory is a bit hazy here >now, but as I recall the ULA would enable ROM and read character data from it >row by row across the scanline. And it didn't want to do it from the RAM. It was one of those "so near and yet so far" cases -- the base of the character matrix table in ROM was pointed to by a register -- IX, IIRC -- and it was trivial to make it point somewhere else. Point it at various places in the ROM, and you got character matrices on screen corresponding with the bit of ROM you'd pointed it at. Point it somewhere in RAM and you got black (or white for reverse-video characters). Man, that was a frustrating discovery -- if the thing had been able to read its character matrices from RAM... There was code around that produced "high resolution" graphics, so it must have been possible to convince the display hardware to read character data from RAM. I just wished I knew the trick... -- don ###### From: autismuk@aol.com (AutismUK) Newsgroups: alt.folklore.computers Subject: Re: How did ZX81s work? Lines: 38 NNTP-Posting-Host: ladder06.news.aol.com X-Admin: news@aol.com Date: 27 Sep 1999 11:54:31 GMT References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> Organization: AOL, http://www.aol.co.uk X-Newsreader: AOL Offline Reader Message-ID: <19990927075431.08677.00000763@ngol06.aol.com> Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!isdnet!newsfeed.cwix.com!howland.erols.net!peerfeed.news.psi.net!portc01.blue.aol.com!audrey03.news.aol.com!not-for-mail In article <37EE1D6D.B76C3328@egg.chips.and.spam.com>, fungus writes: >On a 16k machine this wasn't necessary so the display got fully >expanded (control bit in the PAL?), no control chars necessary. No, the control characters are still there. A specific bit (bit 6) in the display file decided whether an instruction would be "executed" or "displayed". The RET instruction was used ($C9) to terminate it (I think). I wrote an emu for this some time ago. It is quite ingenious, but actually quite simple. I'm generating video using a AVR8515 at 4Mhz ; the best resolution I can get (with no external hardware) is about 70 pixels across (PAL) >Going back to the subject: > >On a single scan line the Z80 could only move about 16 bytes >of data so there's no way it could look up characters in ROM >or anythign like that. It is part of the fetch/execute cycle. It 'fetches' the instruction and sort of decodes it, but bit 6 = 0 forces the instruction to $00 (NOP ?) and feeds the instruction byte, + the Interrupt register as the high byte, into the ROM, which is then multiplexed out by the Dot Clock. Sort of. The CPU is actually "executing" the display file, so it can do it at 3.58Mhz. About the only alternative method is to use something like the repeated OUT instruction (like LDIR) (OTIR ?) and an 8-1 latch multiplexor. ###### From: dpeschel@u.washington.edu (Derek Peschel) Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: 27 Sep 1999 18:25:08 GMT Organization: University of Washington, Seattle Lines: 25 Message-ID: <7socq4$m4e$1@nntp1.u.washington.edu> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> NNTP-Posting-Host: saul10.u.washington.edu X-Trace: nntp1.u.washington.edu 938456708 22670 (None) 140.142.17.38 X-Complaints-To: help@cac.washington.edu NNTP-Posting-User: dpeschel Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!bignews.mediaways.net!iol.ie!newsfeed.icl.net!colt.net!iad-peer.news.verio.net!news.verio.net!sea-feed.news.verio.net!feed.news.verio.net!news.u.washington.edu!dpeschel In article <938454854.402621@shelley.paradise.net.nz>, Don Stokes wrote: >Peter Pachla wrote: >>When I got a 16K RAM pack for my '81 I designed and built a programmable >>character generator using the internal 1K of RAM. Memory is a bit hazy here >>now, but as I recall the ULA would enable ROM and read character data from it >>row by row across the scanline. > >And it didn't want to do it from the RAM. It was one of those "so near >and yet so far" cases -- the base of the character matrix table in ROM >was pointed to by a register -- IX, IIRC -- and it was trivial to make it >point somewhere else. Point it at various places in the ROM, and you got >character matrices on screen corresponding with the bit of ROM you'd >pointed it at. >There was code around that produced "high resolution" graphics, so it >must have been possible to convince the display hardware to read character >data from RAM. I just wished I knew the trick... I've heard that the hi-res screens are restricted in some way. So it's possible that even they weren't completely general-purpose in convincing the machine to read graphics data from RAM. -- Derek ###### From: "Peter Pachla" Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Tue, 28 Sep 1999 02:40:57 +0100 Organization: WinterMute Lines: 36 Message-ID: <7sp6o1$ha1$1@gxsn.com> References: <37ED9D43.3CD03009@sprynet.com> <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> Reply-To: "Peter Pachla" NNTP-Posting-Host: 195.147.231.8 X-Trace: 938483265 1NNUCNF1GE708C393C gxsn.com X-Complaints-To: abuse@gxsn.com X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2014.211 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2014.211 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!skynet.be!newsfeed.stanford.edu!remarQ73!supernews.com!remarQ.com!remarQ69!gxsn.com!not-for-mail Hi Don, > And it didn't want to do it from the RAM.... Not without some small amount of hardware hacking.... > Point it somewhere in RAM and you got black (or white for reverse-video >characters). Man, that was a frustrating discovery -- if the thing had >been able to read its character matrices from RAM... As I said, I did this a LONG time ago so my memory of how it worked is very sketchy.... As best I recall, the ULA would retrieve character data from ROM (so asserting the ROM /CS signal) when /MREQ was false. Basically all you needed to do was add a circuit which "intercepted" the ROM enable and redirected it to the onboard RAM when /MREQ was false. Of course you needed a few extra gates to allow writing to the RAM (to load character sets) and a latch to enable/disable the programmable character set. But in essence that was pretty much it. TTFN - Pete. -- Spam deflector in effect - it's obvious! "Very funny Scotty, now beam down my trousers!" - J.T.Kirk Hardware & Software Engineer. Sound Engineer. Collector of Arcade Machines, Games Consoles & Obsolete Computers (esp DEC) -- ###### From: "Peter Pachla" Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Tue, 28 Sep 1999 02:47:04 +0100 Organization: WinterMute Lines: 23 Message-ID: <7sp6o3$ha1$2@gxsn.com> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> Reply-To: "Peter Pachla" NNTP-Posting-Host: 195.147.231.8 X-Trace: 938483267 1NNUCNF1GE708C393C gxsn.com X-Complaints-To: abuse@gxsn.com X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2014.211 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2014.211 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!skynet.be!hermes.visi.com!news-out.visi.com!remarQ73!supernews.com!remarQ.com!remarQ69!gxsn.com!not-for-mail Hi Derek, > I've heard that the hi-res screens are restricted in some way. >So it's possible that even they weren't completely general-purpose >in convincing the machine to read graphics data from RAM. I never looked into this at the time, but I always assumed that they worked by redefining the character set "on the fly" as it were? TTFN - Pete. -- Spam deflector in effect - it's obvious! "Very funny Scotty, now beam down my trousers!" - J.T.Kirk Hardware & Software Engineer. Sound Engineer. Collector of Arcade Machines, Games Consoles & Obsolete Computers (esp DEC) -- ###### From: evans_the_swim@dontbothermewithspam.tesco.net Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Tue, 28 Sep 1999 06:49:36 GMT Organization: Tesco ISP Lines: 47 Message-ID: <37efe80d.257812128@news.tesco.net> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> NNTP-Posting-Host: 212.140.73.23 X-Newsreader: Forte Free Agent 1.11/32.235 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!isdnet!newsfeed.icl.net!newspeer.clara.net!news.clara.net!btnet-peer!btnet!mendelevium.btinternet.com!not-for-mail On 27 Sep 1999 18:25:08 GMT, dpeschel@u.washington.edu (Derek Peschel) wrote: >In article <938454854.402621@shelley.paradise.net.nz>, >Don Stokes wrote: >>Peter Pachla wrote: > >>>When I got a 16K RAM pack for my '81 I designed and built a programmable >>>character generator using the internal 1K of RAM. Memory is a bit hazy here >>>now, but as I recall the ULA would enable ROM and read character data from it >>>row by row across the scanline. >> >>And it didn't want to do it from the RAM. It was one of those "so near >>and yet so far" cases -- the base of the character matrix table in ROM >>was pointed to by a register -- IX, IIRC -- and it was trivial to make it >>point somewhere else. Point it at various places in the ROM, and you got >>character matrices on screen corresponding with the bit of ROM you'd >>pointed it at. > >>There was code around that produced "high resolution" graphics, so it >>must have been possible to convince the display hardware to read character >>data from RAM. I just wished I knew the trick... > >I've heard that the hi-res screens are restricted in some way. So it's >possible that even they weren't completely general-purpose in convincing the >machine to read graphics data from RAM. I had the zx81 and got the hi-res software. The routines and display were contained in a REM statement at the start of the program. I can't remember if you had to run a routine to initialise the thing to use the portion of the REM statement as display ram but think it VERY likely. As I recall it has 256 x 192 (or 192 x 256, can't remember) bits, for about a 6K display file. The routines would set/reset a particular bit (note I did not say pixel - see below), or print a character at a specific location. The wrinkle I remember was that setting a bit beside another set (or reset) bit might shift the displayed pixel. Cool. Man, I had lots of stuff for that thing. UHF display, reverse video, reset switch (used that A LOT), auto key repeat, 64K soldered on, the printer, a real keyboard (hours with the soldering iron, it seems), built it into a case with power supply, had the modem/serial port and had that port tweaked to 600 baud, assembler, debugger, forth, the software fastloader routines, and a bunch of stuff I have forgotten, no doubt. Loads of fun. ###### From: john@ucc.gu.uwa.edu.au (John "West" McKenna) Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: 28 Sep 1999 09:45:16 +0800 Organization: The University of Western Australia Lines: 11 Message-ID: <7sp6jc$aqv$1@mermaid.ucc.gu.uwa.edu.au> References: <37ED9D43.3CD03009@sprynet.com> <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> NNTP-Posting-Host: mermaid.ucc.gu.uwa.edu.au X-Newsreader: NN version 6.5.0 CURRENT #118 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!news.belnet.be!newspump.monmouth.com!newspeer.monmouth.com!newsfeed.berkeley.edu!enews.sgi.com!harbinger.cc.monash.edu.au!news.uwa.edu.au!not-for-mail don@news.daedalus.co.nz (Don Stokes) writes: >There was code around that produced "high resolution" graphics, so it >must have been possible to convince the display hardware to read character >data from RAM. I just wished I knew the trick... To the best of my knowledge, it didn't. It just used parts of the ROM that happened to have the correct bytes, and changed the 'character set' every scan line. John West ###### From: autismuk@aol.com (AutismUK) Newsgroups: alt.folklore.computers Subject: Re: How did ZX81s work? Lines: 12 NNTP-Posting-Host: ladder05.news.aol.com X-Admin: news@aol.com Date: 28 Sep 1999 10:20:55 GMT References: <7sp6o3$ha1$2@gxsn.com> Organization: AOL, http://www.aol.co.uk X-Newsreader: AOL Offline Reader Message-ID: <19990928062055.12186.00001255@ngol03.aol.com> Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!news.maxwell.syr.edu!newsfeed.cwix.com!news.compuserve.com!news-master.compuserve.com!portc03.blue.aol.com!audrey01.news.aol.com!not-for-mail In article <7sp6o3$ha1$2@gxsn.com>, "Peter Pachla" writes: > > I've heard that the hi-res screens are restricted in some way. > >So it's possible that even they weren't completely general-purpose > >in convincing the machine to read graphics data from RAM. > >I never looked into this at the time, but I always assumed that they worked >by >redefining the character set "on the fly" as it were? Nope, it is full high resolution. ###### From: Trent Worthington Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Thu, 30 Sep 1999 06:07:34 -0400 Organization: Posted via Supernews, http://www.supernews.com Lines: 15 Message-ID: <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> X-Complaints-To: newsabuse@supernews.com X-Newsreader: Forte Agent 1.6/32.525 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!nyc-news-feed1.bbnplanet.com!washdc3-snh1.gtei.net!cpk-news-hub1.bbnplanet.com!news.gtei.net!remarQ-easT!rQdQ!supernews.com!remarQ.com!news.supernews.com!not-for-mail On Thu, 30 Sep 1999 03:36:06 +0200, fungus wrote: > >I fixed the inevitable bugs by patching the EPROM by >hand, in hex. And rememeber that you can only turn 0s >to 1s unless you erase the entire chip and start over, >so you gotta be damn careful). I always thought that 1's could be made to 0's without erasing. changing to 1's required a UV erase. (Correct me if I am wrong...) ###### From: peter@abbnm.com (Peter da Silva) Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: 30 Sep 1999 13:27:22 GMT Organization: Network/development platform support, NMTI Lines: 18 Message-ID: <7svofq$eaf@web.nmti.com> References: <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> NNTP-Posting-Host: grendel.nmti.com Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!news-fra1.dfn.de!bignews.mediaways.net!news-feed.inet.tele.dk!bofh.vszbr.cz!news-proxy.baileynm.com!web.nmti.com!peter In article <37F2BE86.6EBB94A6@egg.chips.and.spam.com>, fungus wrote: > When I think about all these stunts I used to pull, > I get to wondering if I could still do it all today... Probably not, but only because you don't have to and there's nothing to do it on. There are no equivalent stunts today, because since the Apple II and the Amiga went away there simply aren't any home computers that are either simple enough or well enough documented and designed to have any cracks to wedge your brain into and open them up for play. -- In hoc signo hack, Peter da Silva `-_-' Ar rug tú barróg ar do mhactíre inniu? 'U` "You are trapped in a maze of screens and ssh sessions all alike." "It is dark, and you are likely to log off the wrong account." -- Nep. ###### Path: chonsp.franklin.ch!usenet From: Neil Franklin Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: 30 Sep 1999 20:37:10 +0200 Organization: My own Private Self Lines: 23 Sender: neil@chonsp.franklin.ch Message-ID: <6uwvt8z1nt.fsf@chonsp.franklin.ch> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> X-Newsreader: Gnus v5.3/Emacs 19.34 Trent Worthington writes: > > On Thu, 30 Sep 1999 03:36:06 +0200, fungus > wrote: > > >hand, in hex. And rememeber that you can only turn 0s > >to 1s unless you erase the entire chip and start over, > >so you gotta be damn careful). > > I always thought that 1's could be made to 0's without erasing. > changing to 1's required a UV erase. (Correct me if I am wrong...) All EPROMs I ever used were 1->0 by electricity, 0->1 by UV. Is it a BCC or BCS? First try the one with an extra 1 in it. Thanks for reminding me of such tricks we once all used. Jikes! In 2 months its Nov 1999 and so 10 years since I did my last assembly (diploma work at engineering shool, 68008). -- Neil Franklin, neil@franklin.ch.remove http://neil.franklin.ch/ ###### From: greenaum@BOLLOCKSyahoo.co.uk Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Organization: Rossum's Universal Robots Reply-To: greenaum@BOLLOCKSyahoo.co.uk Message-ID: <3806df53.5510792@news.freeuk.net> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> X-Newsreader: Forte Agent 1.5/32.452 X-No-Archive: yes MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 15 Date: Thu, 30 Sep 1999 22:08:26 GMT NNTP-Posting-Host: 212.126.145.142 X-Complaints-To: abuse@freeuk.net X-Trace: nnrp4.clara.net 938729306 212.126.145.142 (Thu, 30 Sep 1999 23:08:26 BST) NNTP-Posting-Date: Thu, 30 Sep 1999 23:08:26 BST Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!skynet.be!diablo.theplanet.net!newspeer.clara.net!news.clara.net!nnrp4.clara.net.POSTED!not-for-mail You can do true hi-res on a ZX81 but it requires some static RAM chips adding in a custom mod, some Germans have done it, but it doesn't really count. What I think they did, was get pseudo-hires, by changing the characters at the end of each scanline. You were stuck with the bit patterns that were in the ROM, but you could get sort-of graphics out of them. Some genius even wrote a paint program. ------------------------------------------------------------------------ Why pamper life's complexity, when the leather runs smooth on the passenger seee-eee-aaat? - - - - - - - - greenaum@yahoo.co.uk ###### From: genew@shuswap.net (Gene Wirchenko) Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Fri, 01 Oct 1999 19:20:17 GMT Organization: Okanagan Internet Junction Lines: 39 Message-ID: <37f4f147.2252016@news.shuswap.net> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> <37F4B648.A7550CE9@egg.chips.and.spam.com> Reply-To: genew@shuswap.net NNTP-Posting-Host: salmonarm3-28.shuswap.net X-Trace: news.junction.net 938805595 2160 206.87.124.110 (1 Oct 1999 19:19:55 GMT) X-Complaints-To: abuse@junction.net NNTP-Posting-Date: 1 Oct 1999 19:19:55 GMT X-Newsreader: Forte Free Agent 1.1/32.230 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!enews.sgi.com!paloalto-snf1.gtei.net!su-news-hub1.bbnplanet.com!news.gtei.net!newsfeed.direct.ca!cyclone.bc.net!news.junction.net!not-for-mail fungus wrote: > > >Trent Worthington wrote: >> >> On Thu, 30 Sep 1999 03:36:06 +0200, fungus >> wrote: >> >> > >> >> >> >I fixed the inevitable bugs by patching the EPROM by >> >hand, in hex. And rememeber that you can only turn 0s >> >to 1s unless you erase the entire chip and start over, >> >so you gotta be damn careful). >> >> I always thought that 1's could be made to 0's without erasing. >> changing to 1's required a UV erase. (Correct me if I am wrong...) > > >Um, maybe.. > >One or the other, I can't really remember which. The point is >it makes patching EPROMS tricky. Today's object oriented dialog >wizard programmers wouldn't stand a chance... I'm pretty sure that it's 0 to 1. I recall reading of one microprocessor had opcode FF being an interrupt instruction (BRK?) so that one could patch. Sincerely, Gene Wirchenko Computerese Irregular Verb Conjugation: I have preferences. You have biases. He/She has prejudices. ###### Path: chonsp.franklin.ch!usenet From: Neil Franklin Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: 01 Oct 1999 22:43:57 +0200 Organization: My own Private Self Lines: 40 Sender: neil@chonsp.franklin.ch Message-ID: <6uln9merqq.fsf@chonsp.franklin.ch> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> <37F4B648.A7550CE9@egg.chips.and.spam.com> <37f4f147.2252016@news.shuswap.net> X-Newsreader: Gnus v5.3/Emacs 19.34 genew@shuswap.net (Gene Wirchenko) writes: > > fungus wrote: > > > >Trent Worthington wrote: > >> > >> I always thought that 1's could be made to 0's without erasing. > >> changing to 1's required a UV erase. (Correct me if I am wrong...) > > > >One or the other, I can't really remember which. The point is > >it makes patching EPROMS tricky. Real programming is tricky. Trying to teach sand smarts, ya know :-). > >Today's object oriented dialog > >wizard programmers wouldn't stand a chance... They do not stand a chance at anything technical. The only reason they survive is that they do not case inferiority complexes in managers. > I'm pretty sure that it's 0 to 1. It definitely is electric 1->0 and UV 0->1 for 27xx(x) EPROMs. > I recall reading of one > microprocessor had opcode FF being an interrupt instruction (BRK?) so > that one could patch. On the 6502 00 = BRK (software trap), to possibly enter an patch on 1 byte. The Z80 (used in the ZX-81, hey, back on topic!) has 00 = NOP, but it has no BRK instruction anyway, Intel compatible... :-) -- Neil Franklin, neil@franklin.ch.remove http://neil.franklin.ch/ ###### From: hawk@hawkins.cba.uni.edu (Richard E. Hawkins) Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Followup-To: alt.folklore.computers Date: 1 Oct 1999 17:20:07 -0500 Organization: House of Hawkins Lines: 29 Message-ID: <7t3c2n$m89$1@hawkins.cba.uni.edu> References: <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <7svofq$eaf@web.nmti.com> NNTP-Posting-Host: hawkins.cba.uni.edu Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!skynet.be!logbridge.uoregon.edu!news.physics.uiowa.edu!news.uni.edu!not-for-mail [followup limited to alt.folklore.computers] In article <7svofq$eaf@web.nmti.com>, Peter da Silva wrote: >In article <37F2BE86.6EBB94A6@egg.chips.and.spam.com>, >fungus wrote: >> When I think about all these stunts I used to pull, >> I get to wondering if I could still do it all today... >Probably not, but only because you don't have to and there's nothing to do >it on. >There are no equivalent stunts today, because since the Apple II and the >Amiga went away there simply aren't any home computers that are either >simple enough or well enough documented and designed to have any cracks to >wedge your brain into and open them up for play. Well, there's the ZX81 and a couple of those that came long after the Apple II :) [duck] hawk, who saw an apple II plus at the auction, but didn't buy it because the keys were broken, and he wanted a plain apple II anyway. -- Prof. Richard E. Hawkins, Esq. hawk@hawkins.cba.uni.edu (319) 266-7114 http://eyry.econ.iastate.edu/hawk These opinions will not be those of UNI until it pays my retainer. ###### From: Phil Hays Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Fri, 01 Oct 1999 20:10:35 -0700 Organization: Real email is pdhays at same service Lines: 11 Message-ID: <37F577AB.8123C0B4@sprynet.com> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> <37F4B648.A7550CE9@egg.chips.and.spam.com> <37f4f147.2252016@news.shuswap.net> <6uln9merqq.fsf@chonsp.franklin.ch> NNTP-Posting-Host: a5.79.25.a7 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Server-Date: 2 Oct 1999 03:05:47 GMT X-Mailer: Mozilla 4.08 [en] (WinNT; U) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!skynet.be!remarQ-easT!supernews.com!remarQ.com!news.mindspring.net!firehose.mindspring.com!not-for-mail Neil Franklin wrote: > It definitely is electric 1->0 and UV 0->1 for 27xx(x) EPROMs. 1702's were electroic 0->1, as they were PMOS. -- Phil Hays "Irritatingly, science claims to set limits on what we can do, even in principle." Carl Sagan ###### From: genew@shuswap.net (Gene Wirchenko) Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Sat, 02 Oct 1999 04:10:45 GMT Organization: Okanagan Internet Junction Lines: 31 Message-ID: <37f55b50.29392259@news.shuswap.net> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> <37F4B648.A7550CE9@egg.chips.and.spam.com> <37f4f147.2252016@news.shuswap.net> <6uln9merqq.fsf@chonsp.franklin.ch> Reply-To: genew@shuswap.net NNTP-Posting-Host: salmonarm3-22.shuswap.net X-Trace: news.junction.net 938837405 13961 206.87.124.104 (2 Oct 1999 04:10:05 GMT) X-Complaints-To: abuse@junction.net NNTP-Posting-Date: 2 Oct 1999 04:10:05 GMT X-Newsreader: Forte Free Agent 1.1/32.230 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!skynet.be!cyclone.bc.net!news.junction.net!not-for-mail Neil Franklin wrote: >genew@shuswap.net (Gene Wirchenko) writes: [snip] >> I recall reading of one >> microprocessor had opcode FF being an interrupt instruction (BRK?) so >> that one could patch. > >On the 6502 00 = BRK (software trap), to possibly enter an patch on 1 >byte. $%^%^#! I think it *was* the 6502 and if so, bit rot! Maybe my source had it wrong? I just checked with a 6502 book I have and it agrees with you. I'm no expert: I only ever wrote one routine in 6502 (and learned to hate it in that time). >The Z80 (used in the ZX-81, hey, back on topic!) has 00 = NOP, but it >has no BRK instruction anyway, Intel compatible... :-) The Z-80 is what I did most of my asm in. Sincerely, Gene Wirchenko Computerese Irregular Verb Conjugation: I have preferences. You have biases. He/She has prejudices. ###### From: Scott Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Message-ID: <021019991332529710%scottm25@bigfoot.com> References: <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <7svofq$eaf@web.nmti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: 8bit User-Agent: YA-NewsWatcher/4.2.4 Lines: 11 Date: Sat, 02 Oct 1999 13:32:52 -0400 NNTP-Posting-Host: 207.103.134.57 X-Complaints-To: abuse@voicenet.com X-Trace: news3.voicenet.com 938885569 207.103.134.57 (Sat, 02 Oct 1999 13:32:49 EDT) NNTP-Posting-Date: Sat, 02 Oct 1999 13:32:49 EDT Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!uunet!ams.uu.net!ffx.uu.net!news.globix.net!netnews.com!news.voicenet.com!news3.voicenet.com!scottm25 In article <7svofq$eaf@web.nmti.com>, Peter da Silva wrote: > There are no equivalent stunts today, because since the Apple II and the > Amiga went away there simply aren't any home computers that are either > simple enough or well enough documented and designed to have any cracks to > wedge your brain into and open them up for play. > I was just thinking about that the other day while I was playing Archon on my 128D. It got me so nostalgic I pulled out the //e and went browsing through disks. Ah, the good old days. :-) ###### Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? From: bmarcum@iglou.com X-Everything: Net-Tamer V 1.08X NNTP-Posting-Host: lou-ts10-25.iglou.com X-Original-NNTP-Posting-Host: lou-ts10-25.iglou.com Message-ID: <37f6ed55@news.iglou.com> Date: 3 Oct 1999 01:44:53 -0500 X-Trace: 3 Oct 1999 01:44:53 -0500, lou-ts10-25.iglou.com X-Original-NNTP-Posting-Host: news-incoming.iglou.com Organization: IgLou Internet Services, Inc. Lines: 13 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!newsfeeds.belnet.be!news.belnet.be!colt.net!dispose.news.demon.net!demon!newsfeed.berkeley.edu!logbridge.uoregon.edu!nuq-peer.news.verio.net!news.verio.net!uunet!lax.uu.net!ffx.uu.net!news.iglou.com!lou-ts10-25.iglou.com On 1999-10-01 neil@franklin.ch.remove said: >On the 6502 00 = BRK (software trap), to possibly enter an patch on >1 byte. >The Z80 (used in the ZX-81, hey, back on topic!) has 00 = NOP, but >it has no BRK instruction anyway, Intel compatible... :-) FF on the Z80 is RST 38 (or RST 7 depending on the assembler), which is close enough to a BRK (for those who don't know 8080/Z80, an RST is a one-byte subroutine call to one of eight addresses.) Net-Tamer V 1.08X - Test Drive ###### Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? References: <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <7svofq$eaf@web.nmti.com> <021019991332529710%scottm25@bigfoot.com> Organization: Chez Inwap From: inwap@best.com (Joe Smith) Date: 03 Oct 1999 09:50:13 GMT Lines: 35 Message-ID: <37f726d5$0$211@nntp1.ba.best.com> NNTP-Posting-Host: shell3.ba.best.com X-Trace: nntp1.ba.best.com 938944213 211 inwap@206.184.139.134 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!isdnet!nntp.abs.net!news.voicenet.com!news2.best.com!news3.best.com!nntp1.ba.best.com!not-for-mail In article <021019991332529710%scottm25@bigfoot.com>, Scott wrote: >In article <7svofq$eaf@web.nmti.com>, Peter da Silva >wrote: > >> There are no equivalent stunts today, because since the Apple II and the >> Amiga went away there simply aren't any home computers that are either >> simple enough or well enough documented and designed to have any cracks to >> wedge your brain into and open them up for play. >> >I was just thinking about that the other day while I was playing Archon >on my 128D. It got me so nostalgic I pulled out the //e and went >browsing through disks. Ah, the good old days. :-) I saw as lot of functional Commodore 128s and Apple IIs at the Third Annual Vintage Computer Faire today. http://www.vintage.org Ob PDP-10: Remember when TOPS-10 had the useless feature of "SET TTY DISPLAY"? Eventually that bit was redefined to mean that the terminal was some sort of CRT (glass TTY) that was capable of deleting characters from the screen with backspace-space-backspace. But the original definition of the DISPLAY bit was that this TTY was connected to a GT40 (PDP-11 with vector graphics display, keyboard and lightpen). Eric Smith showed up with a functional GT40, complete with the game of Lunar Lander. Programs could be downloaded into the GT40's memory by sending an escape sequence and 6-bit data from the PDP-10. Or any other device capable of sending about 100Kbytes of data through a serial port. Including a Palm Pilot. -Joe -- INWAP.COM is Joe Smith, Sally Smith and our cat Murdock. (The O'Hallorans and their cats moved to http://www.tyedye.org/ Nov-98.) See http://www.inwap.com/ for PDP-10, "ReBoot", "Shadow Raiders"/"War Planets" ###### From: "Rob Nicholson" Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Sun, 3 Oct 1999 21:54:51 +0100 Organization: Customer of Planet Online Lines: 8 Message-ID: <7t8ggb$7gf$1@news8.svr.pol.co.uk> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> <37F4B648.A7550CE9@egg.chips.and.spam.com> <37f4f147.2252016@news.shuswap.net> <6uln9merqq.fsf@chonsp.franklin.ch> <37f55b50.29392259@news.shuswap.net> NNTP-Posting-Host: modem-86.xenon.dialup.pol.co.uk X-Trace: news8.svr.pol.co.uk 938984779 7695 62.136.26.214 (3 Oct 1999 21:06:19 GMT) NNTP-Posting-Date: 3 Oct 1999 21:06:19 GMT X-Complaints-To: abuse@theplanet.net X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2014.211 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2014.211 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!skynet.be!diablo.theplanet.net!news.theplanet.net!newspost.theplanet.net!not-for-mail > $%^%^#! I think it *was* the 6502 and if so, bit rot! Maybe my > source had it wrong? I just checked with a 6502 book I have and it Hmm not sure - $EA springs to mind. Rob. ###### From: "Peter Pachla" Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Mon, 4 Oct 1999 14:30:39 +0100 Organization: WinterMute Lines: 22 Message-ID: <7taj8g$smr$1@gxsn.com> References: <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <7svofq$eaf@web.nmti.com> <021019991332529710%scottm25@bigfoot.com> <37f726d5$0$211@nntp1.ba.best.com> Reply-To: "Peter Pachla" NNTP-Posting-Host: 195.147.228.68 X-Trace: 939053136 1NNUCNF1GE444C393C gxsn.com X-Complaints-To: abuse@gxsn.com X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2014.211 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2014.211 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!newspeer.te.net!news.indigo.ie!diablo.theplanet.net!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!howland.erols.net!news-out.supernews.com.MISMATCH!remarQ73!supernews.com!remarQ.com!remarQ69!gxsn.com!not-for-mail Hi, >....Smith showed up with a functional GT40, complete with the game >of Lunar Lander. I've been looking for a GT-40 for a couple of years now on and off, any idea where I might find one here in the UK? TTFN - Pete. -- Spam deflector in effect - it's obvious! "Very funny Scotty, now beam down my trousers!" - J.T.Kirk Hardware & Software Engineer. Sound Engineer. Collector of Arcade Machines, Games Consoles & Obsolete Computers (esp DEC) -- ###### From: scottw@bmtech.co.uk_DELETE_THIS (Scott Wheeler) Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Mon, 04 Oct 1999 15:23:19 GMT Message-ID: <37f8c629.1634287441@192.168.0.1> References: <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <7svofq$eaf@web.nmti.com> <021019991332529710%scottm25@bigfoot.com> <37f726d5$0$211@nntp1.ba.best.com> NNTP-Posting-Host: bmtech.demon.co.uk X-NNTP-Posting-Host: bmtech.demon.co.uk:158.152.102.124 X-Trace: news.demon.co.uk 939050403 nnrp-06:16134 NO-IDENT bmtech.demon.co.uk:158.152.102.124 X-Complaints-To: abuse@demon.net X-Newsreader: Forte Agent 1.5/32.451 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 17 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!isdnet!newsfeed.icl.net!dispose.news.demon.net!demon!news.demon.co.uk!demon!bmtech.demon.co.uk!not-for-mail On 03 Oct 1999 09:50:13 GMT, inwap@best.com (Joe Smith) wrote: >Ob PDP-10: Remember when TOPS-10 had the useless feature of "SET TTY >DISPLAY"? ... > >Programs could be downloaded into the GT40's memory by sending an escape >sequence and 6-bit data from the PDP-10. Or any other device capable of >sending about 100Kbytes of data through a serial port. Including a >Palm Pilot. Wasn't that the technique used on some MS/DOS sw to establish a link between a portable (3.5" disk) and a desktop (5 1/4" disk only, at that time)? Scott -- (please de-mung address if replying by email) ###### From: genew@shuswap.net (Gene Wirchenko) Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Mon, 04 Oct 1999 16:15:10 GMT Organization: Okanagan Internet Junction Lines: 20 Message-ID: <37f83d08.44830141@news.shuswap.net> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> <37F4B648.A7550CE9@egg.chips.and.spam.com> <37f4f147.2252016@news.shuswap.net> <6uln9merqq.fsf@chonsp.franklin.ch> <37f55b50.29392259@news.shuswap.net> <7t8ggb$7gf$1@news8.svr.pol.co.uk> Reply-To: genew@shuswap.net NNTP-Posting-Host: salmonarm3-40.shuswap.net X-Trace: news.junction.net 939053694 13856 206.87.124.122 (4 Oct 1999 16:14:54 GMT) X-Complaints-To: abuse@junction.net NNTP-Posting-Date: 4 Oct 1999 16:14:54 GMT X-Newsreader: Forte Free Agent 1.1/32.230 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!news.maxwell.syr.edu!cyclone.bc.net!news.junction.net!not-for-mail "Rob Nicholson" wrote: >> $%^%^#! I think it *was* the 6502 and if so, bit rot! Maybe my >> source had it wrong? I just checked with a 6502 book I have and it > >Hmm not sure - $EA springs to mind. The book I checked for BRK was Lance A. Levanthal's "6502 Assembly Language Programming", ISBN 0-931988-27-6. I just had another look in it and $EA is NOP. Sincerely, Gene Wirchenko Computerese Irregular Verb Conjugation: I have preferences. You have biases. He/She has prejudices. ###### From: evans_the_swim@dontbothermewithspam.tesco.net Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Mon, 04 Oct 1999 21:33:16 GMT Organization: Tesco ISP Lines: 26 Message-ID: <37f8eb1f.40516347@news.tesco.net> References: <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <7svofq$eaf@web.nmti.com> <021019991332529710%scottm25@bigfoot.com> <37f726d5$0$211@nntp1.ba.best.com> <37f8c629.1634287441@192.168.0.1> NNTP-Posting-Host: 212.140.65.232 X-Newsreader: Forte Free Agent 1.11/32.235 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!news.maxwell.syr.edu!btnet-peer!btnet!mendelevium.btinternet.com!not-for-mail On Mon, 04 Oct 1999 15:23:19 GMT, scottw@bmtech.co.uk_DELETE_THIS (Scott Wheeler) wrote: >On 03 Oct 1999 09:50:13 GMT, inwap@best.com (Joe Smith) wrote: > >>Ob PDP-10: Remember when TOPS-10 had the useless feature of "SET TTY >>DISPLAY"? ... >> >>Programs could be downloaded into the GT40's memory by sending an escape >>sequence and 6-bit data from the PDP-10. Or any other device capable of >>sending about 100Kbytes of data through a serial port. Including a >>Palm Pilot. > >Wasn't that the technique used on some MS/DOS sw to establish a link >between a portable (3.5" disk) and a desktop (5 1/4" disk only, at >that time)? > The brother 100K and 200K disk drives for the tandy M100/102/Kyocera KC85/Olivetti something-or-other/NEC 8201(a) had enough smarts that you could load a routine into them and it would then find the os on the disk and load it into the machine's memory. The CBM C64 drives also had smarts that I think you could use to get one drive to copy to another with no computer inbetween - after you fiddled with it, of course. ###### From: Deborah Gronke Bennett Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: 05 Oct 1999 13:16:46 -0700 Organization: Sun Microsystems, Microelectronics Lines: 21 Message-ID: References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> <6uwvt8z1nt.fsf@chonsp.franklin.ch> NNTP-Posting-Host: mayfield.eng.sun.com X-Newsreader: Gnus v5.5/Emacs 20.3 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!isdnet!logbridge.uoregon.edu!su-news-hub1.bbnplanet.com!denver-news-feed1.bbnplanet.com!news.gtei.net!namche.sun.com!news2me.EBay.Sun.COM!engnews2.Eng.Sun.COM!not-for-mail Neil Franklin writes: > Trent Worthington writes: > > > > On Thu, 30 Sep 1999 03:36:06 +0200, fungus > > wrote: > > > > >hand, in hex. And rememeber that you can only turn 0s > > >to 1s unless you erase the entire chip and start over, > > >so you gotta be damn careful). > > > > I always thought that 1's could be made to 0's without erasing. > > changing to 1's required a UV erase. (Correct me if I am wrong...) > > All EPROMs I ever used were 1->0 by electricity, 0->1 by UV. > And all bits (at least in a 2532) read as ones if you ever plugged the chip in the wrong way around and blew open all the cells. Made a pretty flashlight for a few seconds too . . . ###### From: "Rob Nicholson" Newsgroups: alt.folklore.computers,alt.sys.pdp8,alt.sys.pdp11,alt.sys.pdp10 Subject: Re: How did ZX81s work? Date: Tue, 5 Oct 1999 18:37:46 +0100 Organization: Customer of Planet Online Lines: 7 Message-ID: <7tdqet$nbl$1@news8.svr.pol.co.uk> References: <37EE1D6D.B76C3328@egg.chips.and.spam.com> <7smeq0$g3m$3@gxsn.com> <938454854.402621@shelley.paradise.net.nz> <7socq4$m4e$1@nntp1.u.washington.edu> <37efe80d.257812128@news.tesco.net> <37F2BE86.6EBB94A6@egg.chips.and.spam.com> <9TXzN+BEWZnY6nmzTyWr8wPXMtvh@4ax.com> <37F4B648.A7550CE9@egg.chips.and.spam.com> <37f4f147.2252016@news.shuswap.net> <6uln9merqq.fsf@chonsp.franklin.ch> <37f55b50.29392259@news.shuswap.net> <7t8ggb$7gf$1@news8.svr.pol.co.uk> <37f83d08.44830141@news.shuswap.net> NNTP-Posting-Host: modem-42.nitrogen.dialup.pol.co.uk X-Trace: news8.svr.pol.co.uk 939158813 23925 62.136.3.42 (5 Oct 1999 21:26:53 GMT) NNTP-Posting-Date: 5 Oct 1999 21:26:53 GMT X-Complaints-To: abuse@theplanet.net X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2014.211 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2014.211 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!newsfeed-zh.ip-plus.net!news.ip-plus.net!News.Amsterdam.UnisourceCS!uunet!ams.uu.net!newsfeed2.news.nl.uu.net!sun4nl!newspeer.ebone.net!diablo.theplanet.net!news.theplanet.net!newspost.theplanet.net!not-for-mail > I just had another look in it and $EA is NOP. Ah - that's why I probably remember it. Rob.