test-drb October 2001

test-drb@ccmp.vtda.org

259 participants
770 discussions

by dittman＠dittman.net

> Now, it occurred to me that you may have thought "ohhh, DLT drive, 10 to 20 > GB per tape." and if that was the case I hate to disappoint you. You'd > would need to find a TZ89 rather than a TZ85. The 20GB uncompressed drive is the TZ88/DLT4000. -- Eric Dittman dittman(a)dittman.net Check out the DEC Enthusiasts Club at http://www.dittman.net/

24 years, 1 month

6502 BASIC or Assembler and Intel 8271/WDC 1770 info req'd

by dittman＠dittman.net

> > So now I'm left with two questions: > > 1) Has anyone got any source code for the WD1770? 6502 ASM, C, anything. > > The 1770 is pretty much compatible with the other Western Digital FDCs. > The TRS-80 model 4 uses the 1793 (very similar in software), and the > sources of LS-DOS 6.3.1 are on the web somewhere (Tim Mann's page?). > That's Z80 assembly language. The later (gate array) TRS-80 Model 4 systems used a 1773 FDC, which was compatible with the 1793. The 1770 and 1773 were compatible, differing only in the logic states of some of the lines, but it's been so long since I've used either I can't remember which pins were different. The 1770/1772/1773 had both the data separator and write precompensation built-in. They are 28 pin devices (the 1793 is a 40 pin device). -- Eric Dittman dittman(a)dittman.net Check out the DEC Enthusiasts Club at http://www.dittman.net/

24 years, 1 month

6502 BASIC or Assembler and Intel 8271/WDC 1770 info req'd

by dittman＠dittman.net

> > The later (gate array) TRS-80 Model 4 systems used a 1773 FDC, which was > > Interesting. The older model 4s (like mine) have a 1793 -- the floppy > controller board is indentical to that in a model 3. I'd assumed they > used that board in the gate array versions as well. > > Maybe they did (in the early gate array machines), and then changed to > the 1773 for the last ones. I don't see any reason why that couldn't have > been done -- as you said the 1773 and 1793 are pretty much compatible. The early systems weren't gate array systems. The gate array Model 4 and 4P systems had the FDC and RS232 integrated on the mainboard. If you have a separate FDC and/or RS232 board then your mainboard is not a gate array model. -- Eric Dittman dittman(a)dittman.net Check out the DEC Enthusiasts Club at http://www.dittman.net/

24 years, 1 month

ZX81 kits (was Re: Keep or assemble???)

by acme_ent＠bellsouth.net

> > The ULA does a lot more than handle the display ;>) > > CPU clock generation (which would be useful). Address decoding (which I'd > want to modify if I was changing the amount of RAM). Very interesting -- how much RAM are you talking about adding that you have to modify the address decoding? > > Of course not ;>) But a ZX81 kit is still faster than starting from > > scratch. > > Is it? It's not going to take long to wire-wrap a clock circuit and > address decoder, and stick in the Z80. It depends _very much_ on how much > of the ZX81 you want to use... Which in turn depends on what the intended use of the finished device is. Since I want a "general purpose" computer the ROM BASIC functions are very convenient, and fast if called directly. Other applications of the Z80 would not need this code so a quickie Z80 board would be fine. > > Try desoldering the RF modulator from a ZX81 board ;>) > > Well, I had never tried to do it before, so I grabbed a ZX81, What, do you have a pile of these? > unscrewed > the case and attacked it with soldering iron and sucker. > > What's the catch? In the US versions which have 3 thin wires, they sometimes become brittle and break. Tony (and others), a question: in your opinion, which microprocessor was the most well-designed (even if not implemented)? Glen 0/0

24 years, 1 month

Hard Drives

by CByrd87043＠aol.com

I have a Hard Drive model P1200-2af. I need to know where can I send it to get it fix or replace. It just stop working.

24 years, 1 month

6502 Source....

by pete＠dunnington.u-net.com

On Oct 7, 17:14, Alex White wrote: > Hey all UK people - do you know of a source for 6502s (and related support > chips, such as the 6522) within the UK? Farnell still list the CMD version, G65SC02, catalogue number 562-750, and the Rockwell R65C102, cat.no. 388-488, though the Rockwell parts is listed as "available until stocks are exhausted". They also list several varieties of 6520, 6521, and a 6545 (Rockwell version of 6845 CRT controller), but I know of no suppliers for new 6522s. -- Pete Peter Turnbull Network Manager University of York

24 years, 1 month

Is there a source for veroboard in the U.S.?

by erd_6502＠yahoo.com

I wanted to bang out a quick thing involving bussed lines (an LED display for a Dragon's Lair game, if you're curious). I thought it might be quick to do with veroboard as opposed to point-to-point wiring. I want to make a prototype before considering burning a board (since that's a weakness I have at the moment anyway - lack of knowledge about layout tools). The problem is that I haven't seen veroboard for sale in the States, only the U.K. and perhaps Western Europe. Here, we have lots of modular prototyping board, but it's not easy to use when you have a lot of parallel connections (like a data bus). Are there any sources on this side of the pond? If not, how much does a sheet of about 6"x9" cost? If it's too expensive to buy and ship, I have several square feet of plain blue perfboard I got from the Micro Center when they put all their hobbyist stuff on remainder, and I'll build it from scratch. I went to school in England in 1985 - New College, specifically, down the street from Blackwell's Books. I spent many hours there absorbing everything I could about hardware hacking (not having the budget to _buy_ the books - the Turf Tavern was closer to the gate ;-) I remember a couple books with do-it-yourself projects using veroboard. Now I wish I'd gotten more books and less beer (but it was _great_ beer) :-) Any veroboard pointers? Thanks, -ethan __________________________________________________ Do You Yahoo!? NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1

24 years, 1 month

IBM ROM BASIC or lack thereof

by acme_ent＠bellsouth.net

Tony Duell wrote: > Since they never did provide BASIC they had to make INT 18 do something > (remember an application program could, in theory, call that interrupt). > Since that interrupt should have entered ROM BASIC, the most sensible > thing to do was to print that there was no ROM BASIC and then halt the > CPU. Since "they never did provide BASIC" then there was *always* "no ROM BASIC." That's like stopping the machine with a message stating "no printer." Why not display something understandable to a common user, such as "no bootable device?" Glen 0/0

24 years, 1 month

6502 BASIC or Assembler and Intel 8271/WDC 1770 info req'd

by philpem＠bigfoot.com

On Sat, 6 Oct 2001 at 01:25:28 +0100 (BST), ard(a)p850ug1.demon.co.uk (Tony Duell) said: > > BTW, I also need some info on the Intel 8271 disk controller - I've got two > > I would not do a new design using the 8271. The chip is fairly hard to > find now, and there are machines that _need_ them (like the old Acorn > Systems). OK, then. One 8271, starting bid $100 - just kidding :-) > In fact, I'd probably use one of the all-in-one PC floppy controller > chips unless there was a very good reason not to. Add a crystal and > perhaps some cable driver chips. That's all... Is "I don't know any suppliers for PC FDCs" a good reason? Farnell Electronics don't seem to sell them, nor do Maplins, Electrovalue, ESR Electronics or any other supplier I know. Care to tell me where I can get them? > > of these little devils and Intel's datasheet makes absolutely no sense at > > all. I've also got a Western Digital WD1770-PH 00-02 that I might be able to > > use instead. First of all, which is the better controller? The 8271 or the > > 1770? Also, is it possible to overclock a 1770 or an 8271 like you can a > > 1772? > > Oh, use the 1770. It does double density (MFM) for one thing (the 8271 is > single-density only). It also require many fewer support circuits I > think. OK, then. The 1770 it is. > The 1770 and 1772 are closely related (the difference being the step > rates the chips can produce). I would guess that the 1770 can be > overclocked, but I've never tried it. I think I'll keep it running at the normal speed (8MHz). But the machine will have a 16MHz oscillator and a divider, with a few jumper blocks for clock speed selection (8 and 16MHz for the FDC, 1, 2 or 4MHz for the 6502 and support circuitry). I've got two Western Design Center W65SC02s (14MHz 6502s! Woohoo!) to play with, plus a Synertek SY6502A (the 2MHz one), two W65SC22s (10MHz WDC 6502s) and two Synertek 6522s (1MHz). So now I'm left with two questions: 1) Has anyone got any source code for the WD1770? 6502 ASM, C, anything. 2) Has anyone got a schematic for a fairly half-decent 16-colour (or better) video card that can be modified to work on a 6502? I've had a look at the NASCOM schematics but I've heard Bad Things(tm) about the NASCOM video system. Aparrently Gemini and a few others produced colour video cards for the NASCOM. Anyone got schematics for these? Graphics would also be nice (the NASCOM video system is text only). BTW, I'd like to avoid obsolete components if that's at all possible. I've got a Hitachi HD6845 but if the 40-odd page datasheet is anything to go by, it's a real dog to use... And it only works in monochrome. I have got a MOS Tech 6568(?) VIC-II, the same one used in the UK Commodore 64. The PSU for this C64 is fried, took out some of the support components with it. TIA. -- Phil. philpem(a)bigfoot.com http://www.philpem.f9.co.uk/

24 years, 1 month

6502 BASIC or Assembler and Intel 8271/WDC 1770 info req'd

by dittman＠dittman.net

> The 1772 and 1770 were designed specifically for use with the 5-1/4" units, > though that's not necessarily what their use today may be. > > I've never seen the 1773 in the flesh, though I've got a data sheet somewhere > (though I've managed to hide it somewhere). The three chips are all similar, > though not identical, in that they have the same data/clock separator circuitr > and write precomp circuit. However, the 1773 lacks some signals that are on the > 1770/72, thereby rendering it less "dedicated" to 5-1/4" drives. The datasheet > did, IIRC, specifically indicate that they're all similar in commands, etc, > though the timing parameters differ somewhat in that the 1770 is slower than the > otherwise identical 1772 in terms of its step rate settings. If I could lay > hands on the 1770/2/3 datasheet, I could tell you which pins differ and in what > sense, but ... The 1773 is also dedicated to 5.25" drives. Your email jogged my memory, and indeed the difference between the 1770 and 1773 was a couple of different signals. I've used the exact same code on both of them. From a programming point of view they are the same. I don't think there was a version of the 1773 with the faster step rates like in the 1772. > If somebody's got a 1773 and wants a 1770, I'll happily swap 'em, just so I have > one in house. If you find a gate array TRS-80 Model 4 then you'd have your 1773. -- Eric Dittman dittman(a)dittman.net Check out the DEC Enthusiasts Club at http://www.dittman.net/

24 years, 1 month

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test-drb October 2001