Wow, a MicroVAX II (BA123 9MB, 3x RD54, 1x TK50, 1x RX50) is going for over $300, and there is still a day left on the auction. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2080763459 I'd expect that for one with a SCSI Qbus module, but this system seems rather vanilla, except for the multiple RD54s. Who'd a thunk it? -brian.

Tothwolf wrote: I think they were shipped broken. You had to be very careful using that door, or the pegs (hinges) would break off. Since all the intresting buttons were under the door, it needed to be opened fairly frequently.

On Mon, 16 Dec 2002, Brian Chase wrote: Cha-CHING!!! There are resellers who pay VERY well for RD54's. I dunno why, with SCSI modules easily available (not cheap, but common), but they do. I recently traded 2 non-DEC Maxtors (4194? The one that is RD54) for a DEC-branded QLogic 1040 and some other baubles. Those things go for $130+ on eBay. Doc

It's my lucky day! It turns out to be a fault with the connection lead - swapping out the original with a spare and everything is hunkydory again! Huzzah! Thanks to all for the offers of help. -- Cheers, Ade. Be where it's at, B-Racing! http://b-racing.com

At 00:05 18/12/2002, you wrote: Well, they were mostly sat on the airconditioner.... However, as you may have seen my followup, it turned out to be something else... That's the one - dodgy cable and/or connector: Using my emergency backup cable solved the trouble instantly & completely. I can now boot to both BASIC & CP/M. -- Cheers, Ade. Be where it's at, B-Racing! http://b-racing.com

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On Wed, 18 Dec 2002, Fred Cisin (XenoSoft) wrote: I once had a drive that was over-riding the write protect mechanism on the floppy because the write-protect sensor failed in some manner. I think I've only ever once come across a bad disk controller on the Apple. Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org * Old computing resources for business and academia at www.VintageTech.com *

On Thu, 19 Dec 2002, Fred Cisin (XenoSoft) wrote: I'm speaking of Apple controllers. I haven't had much (if any) experience with third-party disk controllers for the Apple. One thing about Apple, they are expensive, but they're built very well. Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org * Old computing resources for business and academia at www.VintageTech.com *

On Thu, 19 Dec 2002, Fred Cisin (XenoSoft) wrote: Ooh, juicy! Where can I get one of those? Well, when I go to boot one up after 10, 20, even 30 years, they still work 95% of the time. Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org * Old computing resources for business and academia at www.VintageTech.com *

Sellam Ismail wrote: Fred Cisin wrote: As far as I know, they ONLY worked with 8-inch drives. The one I used only did FM (single density). It's perhaps possible that they might have later offered an MFM (double density) version, although such a controller would have been rather more complicated. On an 8-inch MFM disk, you only get a nominal 16 microseconds per byte transferred, and the reality is that you have to be prepared to handle a byte every 13 microseconds. An Apple ][ can't do that via programmed I/O, so you'd either have to have DMA, or do some tricks. The 8-inch MFM controller I designed for the TLB computer (another 1 MHz 6502 system) used "tricks". The basic idea was that the 6502 code would look like: clc loop: lda fdc_data ; 4 read a byte from the FDC sta buffer,x ; 4 store it to memory inx ; 2 advance pointer bcc loop ; 3 branch always Note that the loop takes exactly 13 cycles. You might ask, "But Eric, what if the FDC doesn't have data ready when the lda instruction is executed?" The FDC was wired to drive the 6502 RDY line (low?) if a read occurred when the data wasn't yet ready. And you might ask how the processor gets out of the loop. That's done by the completion interrupt. The completion interrupt checks the stacked PC, and if the interrupt happened during that loop, changes the stacked PC to the address of the code that cleans up. In order to support reading to a buffer anywhere in memory, the code modified the absolute address in the "sta buffer,x" instruction. Alternatively, an indirect indexed address mode like "sta (ptr),y" could have been used, but it would have taken one cycle longer, which wouldn't have met the required minimum loop time. Note that the buffer was not allowed to cross a page (256-byte) boundary, because that also would add a cycle to the sta instruction timing. The write code was similar: clc wrloop: lda buffer,x ; 4 read a byte from memory sta fdc_data ; 4 write to FDC inx ; 2 advance pointer bcc wrloop ; 3 branch always But this was even more tricky, because the NMOS 6502 doesn't allow the RDY line to stretch a write cycle. [*] For writing, instead of using RDY on the access to the fdc_data register, the card decoded the address of the opcode of the sta instruction of that loop, and drove RDY when that opcode was fetched if the FDC wasn't ready to accept another byte. This meant that the sta instruction had to be at a predetermined address, which was accomplished by putting it in an EPROM. The card had a flip-flop to enable the RDY logic, so that if the system wasn't trying to access the floppy but there was a stray read of the FDC data register [**], the system wouldn't hang. The cards for a TLB computer are fairly large. I didn't think I could cram all the logic onto a standard-sized Apple ][ card back in 1981, although there would have been a better chance with this scheme than with DMA. Eric [*] Contrary to popular belief, this was NOT a bug in the processor. It was done quite deliberately. Back in 1975 when the 6502 was designed, there were plenty of RAMs that could meet the 2 MHz 6502 timing for read and write cycles, but most ROMs (including PROMs and EPROMs) could not. Since you don't ever write to ROMs, they only needed to support stretching the read cycles. Years later, the 65C02 family added the ability to stretch write cycles. [**] The NMOS 6502 would generate a "dummy read" cycle if you used an indexed address mode and a page boundary was crossed. This was especially common on the Apple ][, where accessing the resources on a peripheral card was usually done by indexed addressing, with 16*slot in the index register. The dummy read occurs at an address 256 bytes lower than the desired address, because the carry hasn't yet propogated. This was fixed in the later CMOS parts.

Fred Cisin asks about the SVA 8-inch floppy controller for the Apple ][: I don't see any reason why that shouldn't work.

On Thu, 19 Dec 2002, Fred Cisin (XenoSoft) wrote: Oh wait, I believe I have one then. Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org * Old computing resources for business and academia at www.VintageTech.com *

On Fri, 20 Dec 2002, Eric Smith wrote: I was speaking in future tense, of course ;) (Has it been only two and a half decades?) Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org * Old computing resources for business and academia at www.VintageTech.com *

At 07:47 AM 12/19/02 -0800, you wrote: I have to disagree here -- I have a PowerBook G4 that is not "built very well." The battery latch no longer releases the battery -- a screwdriver is necessary to pry it out. The rubber nubs on either side of the keyboard are gone, leading to an impression of the keyboard pressed into the screen. The latch doesn't always close correctly, or stay closed. Several co-workers have had the case around the headphone jack crack. The hinge eventually loses friction, leading to the inability to keep the screen at the desired angle. Ask Tom Owad about the paint coming off his G4. Cheers, Dan

Well, maybe considered for US consumer (non Mil) companies you're right, But if you compare the Apple ][ wth a BASIS 108, which is literaly the German counterpart, then it's like compareing a Beetle to a Hummer. Gruss H. BTW: hummer.com is one of the best examples of plain arrogance: "To experience HUMMER.COM, we require that you use the latest Internet Explorer or Netscape web browser." -- VCF Europa 4.0 am 03./04. Mai 2003 in Muenchen http://www.vcfe.org/

And what do we look like to outsiders when we run 440V Mainframes to do a P200's job? Hopefully the idea of running such things _full time_ is only a joke. John A. 1.4 Kilowatts, <50 hours a year.

ben franchuk wrote: Correction .02 us or 20 ns for the new machines?

On Sat, 21 Dec 2002, Ernest wrote: That is indeed what it is. Did you get the dual (stacked) disk drive unit with it? Without it I believe the card is generally useless. You may also want to respond to my last message to you ;) Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org * Old computing resources for business and academia at www.VintageTech.com *

At 12:42 PM 12/20/02 +0100, you wrote: Which one is the Hummer, and is that good or bad? If the Apple II was any more robust they would start linking together and take over the world.

On Wed, 18 Dec 2002, Fred Cisin (XenoSoft) wrote: IBM PS/2's usually read and write low-density disks high-density. Peace... Sridhar

Fred Cisin (XenoSoft) cisin(a)xenosoft.com wrote: Since both Fred and Van/Sridhar/ce checked in on this one I probably should shut up, but ISTR that Backup, for one, could & would check the dens. on the 1st disk in a set, but also could be caught Not looking for any Nth (N>1) disk in the set, if it was mismatched. But it wasn't like it couldn't check At All... (machine=PS2m60) My $0.02... John A.

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