test-drb April 1999

test-drb@ccmp.vtda.org

170 participants
1190 discussions

stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies)

by allisonp＠world.std.com

<You can build your own in an FPGA for something on the order of 2500 gates Gates or CPLDs? Big difference there. I do ahve a few 3030s here and can get 4000 seris. But why would I do it. then again I have an early 80s project that was a z80 built in 2901s... at a time where a 10mhz z80 was an extreme machine. Allison

25 years, 9 months

stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies)

by allisonp＠world.std.com

<Think about it! It's really simple and you could easily build it as part o <a gate array. Try that with a Z-80 and see what you get. Did it with 2901s, contemporary to the mid 70s also. If course the 3201 intel two bit slice was in some ways more interesting. Allison

25 years, 9 months

Restoring an 8/E

by danburrows＠mindspring.com

> >The new name for that is dichloromethane IIRC.... Both names are currently used by the solvent vendors. > >And that's basically what 'plastic weld' is (or at least it smells like >it). But in the UK it's almost impossible to get chemicals for home use. >Dunno why, but I suspect sodium chloride would be unavailable if you >asked for it under that name ;-). You just need to know the right people in labs.:) You also don't want to know all the different things I have in my solvent cabinet or the explosion proof refrig. that is in one of my sheds.:) It is amazing what you can get (cheap or free) a lab bankruptcy sales. Especially when you know the people. > >> a 50 or a 100 microliter syringe to dispense it also. > >The easiest way that I've found to use it is to clamp the plastic >together and then to dip a small brush in the solvent and run it along >the crack. It'll be drawn into the crack by capillary action and will >weld the plastic together. I agree but for front panel switches and things that you want to look good without and drips I use the syringe. Then to I have them down to 2 microliter. The 50 microliter one is huge for my usual work. Dan

25 years, 9 months

Restoring an 8/E

by CLASSICCMP＠trailing-edge.COM

>>The new name for that is dichloromethane IIRC.... >Both names are currently used by the solvent vendors. >>And that's basically what 'plastic weld' is (or at least it smells like >>it). But in the UK it's almost impossible to get chemicals for home use. >>Dunno why, but I suspect sodium chloride would be unavailable if you >>asked for it under that name ;-). >You just need to know the right people in labs.:) Or head to your local plastics supplier - all of the ones I've ever dealt with are more than happy to sell you all the useful solvents. Incidentally, for those doing "front panel" restorations, talk to a good sign-making shop. It's rather straightforward these days to get custom plastic panels made and printed. I've had this done several times and have been very satisfied with the results. -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927

25 years, 9 months

Don Lancaster was Re: Ebay Mark-8 Plans

by jon＠techniche.com

Hi Sam, Possible suggestion for a speaker............Steve Ciarcia (SP?) You know the hardware guy who used to have a column in Byte and then started several of his own magazines. He also wrote "how to build a z80 home computer" (or something very close to that, I don't have it in front of me). He came to mind because I've been working in Conn for the last several months and I keep bumping into folks who know him. I also hear that there is a monthly dinner meeting of the ex-members of a now defunct computer club not far >from where I am working and that he often shows up. I know that he cammme on the scene later than some of the other people who have been mentioned as past or future VCF speakers, but he certainly meets the >10 rule. By the way does the VCF pay the speakers? Or their travel? Jon >On Fri, 9 Apr 1999, Joe wrote: > >> At 04:27 PM 4/9/99, Dave wrote: >> > >> >The seller also has the RE TVT plans by Don Lancaster. >> >> Speaking of Don Lancaster, has anyone asked him to speak at VCF or told >> him about this list? He's been involved with the home PCs since the >> beginning and is probably a wealth of infomation. > >I invited him to speak for VCF 1.0 but he wasy busy and told me to try >again some other time. Maybe I'll try again this year. > >On that topic, if anyone would like to suggest a speaker for VCF 3.0 (or >even be a speaker themself!) then please drop me a line with your >suggestion. Thanks! > >Sellam Alternate e-mail: dastar(a)siconic.com >------------------------------------------------------------------------------ >Don't rub the lamp if you don't want the genie to come out. > > Coming in 1999: Vintage Computer Festival 3.0 > See http://www.vintage.org/vcf for details! > [Last web site update: 04/03/99] > >

25 years, 9 months

Restoring an 8/E

by danburrows＠mindspring.com

> >>Try to get some 'plastic weld'. It's a solvent for the sort of plastic >>used on these panels, and you can weld the broken bit back in place. It's >>normally a very strong repair. > >Thanks... I'll keep that in mind... Megan: since you are taking chemistry get a small bottle of methylene chloride. It works wonders as a plastic glue. At the EPA we made aquariums out of Plexiglas and used it for gluing the panels together. You will want a 50 or a 100 microliter syringe to dispense it also. Dan

25 years, 9 months

stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies)

by edick＠idcomm.com

It's not about and indirect table jump, it's about an indirect INDEXED table jump. Dick -----Original Message----- From: Dwight Elvey <elvey(a)hal.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, April 12, 1999 11:12 AM Subject: Re[2]: stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies) >allisonp(a)world.std.com (Allison J Parent) wrote: >> <I knew somebody woudl come up with a good example. That 6809 code is <snip> >> the kinds of things a PC (or other general purpose computer) would. > >Hi > Even the 4004 had an indirect table jump, so what is all the >noise about. >Dwight >

25 years, 9 months

stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies)

by allisonp＠world.std.com

<I knew somebody woudl come up with a good example. That 6809 code is <probably the closest thing I've seen in a micro. The 8051 uses a similar <approach, pointing to the table with the datapointer and uses the The 8051 is very ugly in other places. Then there are the NEC uPD 78xx series that are similar in register layout to z80 but code wise, not close. They have a table lookup instructions for that exact task. They are targetted as rom based controllers and code efficientcy is a requirement but often controller don't need to preocess the kinds of things a PC (or other general purpose computer) would. The z280 has a load address inscrtuction that makes the setup for an indexed jump easier. The PDP-11 did it on one instuction but it has some very powerful addressing modes. Indirection and indexing are natural to that part. However in CPUs righer in register than the 6502, the task would be done far differently. It's a different programming style and it does impact code structure. For example a set of operations that can be done requiring multiple (say a dozen) 16bit parameters to be passed are easily done on even 8080 but the 6502 has to do that as indexed list in ram and pass the pointer to the list if you want to be efficient. It's possible to structure a problem such that any cpu looks good or bad. Generally an application is far more than a trivial few instructions. Look at the PDP-8 which is both register poor and has an instruction set that small is far from adaquate to describe. Yet it performs tasks efficiently in small amounts of core that some cpus can't. The 6809 example would be in PDP-8... / enter here with uart data DCA pindex / store index value at pindex JMP I,INDEX / indirect jump via index (could have been a JMS, jump / subroutine!) Execution time for an 8E (1973) would have been under 8uS if both instuction used indirect addressing. As written it would be 7.6uS. Now the 6502 at 2mhz would have done it in what? < They (DEC) did make the uVax-II as a chipset for interfacing to their <BI-bus, I believe, so that might qualify as well. The DEC chipset probabl <didn't sell for what a 6809 costs, even the faster part, and certainly not <the $0.86 I last saw on the 4MHz Rockwell 65C02. ?????? UvaxII was not for interfacing the BI, that was a dedicated chipset. The uVAXII was a single chip (extended FPU and DMA were companions). UvaxII was only remotely related to BI bus. The statment doesn't parse. <I'm not surprised that it was in the 6809 that this instruction came up. <The 6809 showed lots of promise at first, but once it was in hand, one <clearly could see that it would be MUCH easier going with the MC68008 if on <had to use an 8-bit bus. I never had the opportunity to write in a the 6809 was a bridge part while waiting for the 68K. Still it was a good part. <high-level language for the 6809, but I was told it should have been quite <easy to write a high-quality efficient compiler for it because of its <repertioire of instructions and addressing modes. I turned out literally Nearly as good as the PDP-11. FYI both the 6809 and the 68k had heavy PDP-11 and vax influences. Allison

25 years, 9 months

C for 6502

by jfoust＠threedee.com

At 08:55 PM 4/11/99 -0700, Sellam Ismail wrote: >On Sun, 11 Apr 1999, Richard Erlacher wrote: > >> Have YOU seen a 'C' compiler for any of the 6502 types? > >Aztec C for the Apple ][, for one. I'm sure there were others. I remember buying a C compiler for my Commodore 64 in '83 or so, made by a student at a university in Waterloo, Ontario. My brain is strained to remember the name, though. Aztec C was a popular compiler for the Amiga, too. Wondering what happened to the primary programmer there, who I knew quite well in the Amiga heyday, I found his web page at <http://www.oro.net/~jimg/>. Presto, he's still selling a C compiler for the 65816. He was once involved with the post-Amiga VISCorp set-top effort, and previously unknown to me, was at Bell Labs Murray Hill in '77-79, and wrote a Unix disk driver for the port to the PDP-11/34, and a tiny C for the KIM-1 and Apple II. - John

25 years, 9 months

Don Lancaster was Re: Ebay Mark-8 Plans

by SUPRDAVE＠aol.com

In a message dated 12/04/99 10:29:53 Eastern Daylight Time, jfoust(a)threedee.com writes: << VCF has a generous travel fund, fueled by Intel, Paul Allen, and auctions of antique computer wiring harnesses on eBay. In fact, any member of this mailing list is eligible for grants of up to $1,500 for travel and lodging purposes, if you wish to attend. >> hmmm,. i'd love to go. how does one take advantage of this?

25 years, 9 months

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test-drb April 1999