test-drb January 2008

test-drb@ccmp.vtda.org

221 participants
430 discussions

by cclist＠sydex.com

I just noticed that I have a Toshiba T3100 technical reference manual on my shelf. There's no possibility that I'm going to need it. Anyone collect these beasts who's looking for such a book? No schematics, but lots of programming information. Cheers, Chuck

17 years, 4 months

replies to cctech Digest, Vol 53, Issue 52

by jeffj＠panix.com

------------------------------ From: "UnR00ster" <unr00ster at gmail.com> Subject: Re: 27256 in place of a 2764 >> Under what conditions can a 27256 be used in place of a 2764? I have a >> schematic that calls for the latter, of which I have none, >> but I have lots of the former. > See Ray Carlsen's site > http://staff.washington.edu/rrcc/ > http://personalpages.tds.net/~rcarlsen/cbm/eprompla.txt > adapters http://staff.washington.edu/rrcc/uwweb/EPROM/2x256.gif > and http://staff.washington.edu/rrcc/uwweb/EPROM/2x128.gif > This is all for Commodore stuff, but the idea of using a > modified socket and 512K chip should work for you as well. Very clever! I used to get EE trade rags and a regular advertisor was a socket maker of "correct-a-dip": a daughter-board that you slip under a chip to correct the pinout or add other parts, kinda like the Slocket adapters for CPUs. That's a nice way to do-it-yourself with easy to use, readily available parts and no custom fabrication! ------------------------------ From: "Chuck Guzis" <cclist at sydex.com> Subject: Re: Fast 8Kx2 ROM replacement Message-ID: <479CF645.31339.23B64E5 at cclist.sydex.com> > I don't have the message archives, but I don't think that anyone > mentioned the Cypress CY22016L NVSRAM using QuantumTrap technology. > > Pretty cool stuff; very fast SRAM backed by NV RAM; > at power-up, the SRAM is loaded from the nonvolatile store; > at power-down, it's written (optionally and probably not needed for this application). > > The SRAM has access times of 25, 35 or 45 nsec. and unlimited writes. > The NV RAM is guaranteed for 1,000,000 writes. Why not try for a free sample of the Freescale Magnetoresistive Random Access Memory (MRAM): it's fast and needs no power at all. The largest seems to be P/N PR2A16AVYS35 4MBIT http://www.freescale.com/ ------------------------------ From: dwight elvey <dkelvey at hotmail.com> Subject: RE: 8-bit micro MMU's Message-ID: <BAY138-W18819E7D5B0F64A4281812A3340 at phx.gbl> > One thing that is worth doing that I've seen done on > a Z8000 system is to map instruction memory into > a different area of physical memory than the data memory. > I don't recall but I think there is status information from > the Z80 about what type of fetch or store is being done. I was pondering that long long ago: using the M1 line to differentiate instruction fetch from data read/write. Just one thing: unless it's an embedded system running only from ROM, the loader needs to re-map data areas into program/executable space. Before pipelines, pre-fetching and caches, CPUs accessed RAM with a steady pace and pattern. I can't be the only one to ponder using a Z80 where the M1 cycles (opcode fetch, refrech) went to ROM and non M1 cycles went to RAM, thus allowing other devices to "cycle steal" access to the RAM without interfering with the CPU execution at all (unlike DMA which halts the CPU, or at least all the CPU's bus access). -- Jeff Jonas

17 years, 4 months

A sign of the times

by cclist＠sydex.com

Date: Mon, 28 Jan 2008 11:44:22 -0600 From: Jules Richardson > Does the old printer do what you need better than a new one (build > quality, interfaces, print quality, reliability)? (although you hint at > some answers to that above) Build quality? No--I've mentioned that the Panasonic's an industrial- grade beast. Interfaces? Both have parallel; I've never used the serial or Appletalk interface on the Panasonic, which doesn't have USB. The new Brother is head-and-shoulders above the Panasonic regarding print quality; 1200 dpi vs. 300. Reliability? Hard to say at this point, although I've owned the predecessor model to the Brother for a couple of years and never had a problem. Speed? The Brother is much faster, particularly when rendering graphics; the halftones are superb. At this point, a big factor--cost of operation skews things a lot. Replacement drum and developer cartridges for the Panasonic are getting pretty dear. > How does the expected lifetime if given a new drum stack up against the > cost of new printer(s) (which IME don't seem to be very serviceable or > built to last) While I might find a NOS drum for the Panasonic on eBay for a good price, I'm also aware that the shelf life of OPC drums is finite. If I elect to purchase a remanufactured drum unit, it'll cost me more than $100 plus shipping. The Brother cost me $40 shipped. I suspect that for the shipped price of a single Panasonic drum unit, I could buy three Brothers and stash two of them away for the future. > How guilty do you feel about sending something which could be repaired off > to landfill? It wouldn't go to the landfill. I'd disassemble it and send the metal parts off to recycling and hang onto any interesting mechanicals and electronics for my hellbox. I might try freecycling it, but I saw an HP color laser recently go without a single nibble on the local Freecycle. Some old things, however well made, seem to be eclipsed by more modern technology. Cheers, Chuck

17 years, 4 months

Some new pics available online from the 60's about SEL

by ragooman＠comcast.net

I added some new pics from the 60's about SEL in the gallery There's some with machines used in the glory days of NASA during the Apollo moon project Thanks to Al Kossow and Bob Rosenbloom for helping me find some of these Feel free to take a look http://www2.applegate.org/~ragooman/computers_mini_gallery.html =Dan

17 years, 4 months

8-bit micro MMU's

by thrashbarg＠kaput.homeunix.org

Hi, I'm working on an Z80 MP/M II server for my 8080 CP/M computer and I have been designing a MMU for it. I thought I'd post it here because it could be useful to other builders or better still to talk about any flaws or improvements. The circuit diagram is here: http://kaput.homeunix.org/~thrashbarg/MMU.png Configured like that it is capable of accessing 256kB of RAM with write protection, or 512kB without write protection by using the 'Mem WE' output as an address line. The logical address range is divided up into 2kB pages, where those pages can be of any 2kB page in the physical address range. It's more of a Memory Mapping Unit than a Memory Management Unit. MP/M II needs to remain resident in the highest 13kB of RAM so having the write protection will prevent any runaway processes from crashing the system. 50kB of RAM can be made available to the running program. Pages can be duplicated in the logical address range, so if a process only uses say 4kB of RAM only three pages need to be allocated to it, two for the program itself and one to fill the rest of memory. There may be a need to have a table on disk to tell the OS how many pages to allocate, because a program may use less space on disk than what it requires in memory. The Process ID is determined by the 74174 to the left of the SRAM. When the process changes the 2kB bank making the switch must not change or the program will be moved and probably crash. In MP/M II this wont be an issue because the system bank isn't supposed to move. In this configuration there is a total of 64 processes, 63 if you don't include the system as a process. When an interrupt occurs it clears the PID register to zero so the system can be called to service the interrupt request. The 74175 to the far left controls the MMU and ROM. The ROM is enabled after a reset and the MMU is disabled. This is done by deactivating the left CS of the RAM and connecting the upper address bits of the CPU directly to memory. The remaining two or three address lines should be tied high with resistors, or even connected to the 74LS244 with those inputs tied to +5 or Ground. The tricky element is the 2kB dual port SRAM. I found two of them on an old arcade game board. This lets the CPU program the mapping of memory without having to implement a messy multiplexing system. To program a bank an 11-bit address is loaded into ports F9h and FAh, then the desired bank is programmed to port F8h. The lowest 5 bits of the address selects the desired 2kB page the CPU will access and the remaining 6 digits determine the PID. Maybe they should be split up so one port selects the page and the other selects the PID. Maybe someone can use this? I haven't looked deeply into the MP/M II XIOS requirements so I may have left something out that it needs so is anyone familiar with the XIOS? Cheers, Alexis.

17 years, 4 months

Backing up VAX/VMS?

by mjd.bishop＠emeritus-solutions.com

Building on previous posts: Standalone backup can be installed on the system drive, it gets installed as [.SYSE] and is then started by: >>> B /R5=E0000000 DKA300 Any disks it needs to use must be ready before it goes looking for them during initialisation. The one off creation of the standalone backup kit (i.e. [.SYSE]) goes something like: $set def sys$update $@stabackit [Ref VMS System Manager's Manual] Standalone backup has some limitations, e.g. at ~V5.5 it only supports a cluster size of 1; i.e. it only supports disks up to 1 Gby. This means that you can't use it with RZ27/28/29 StorageWorks (1/2/4/8/.. Gby) disks. On a machine with a SCSI bus and with spare scsi disks to hand my preference would be to write the backup to another blank scsi disk as a save set, and then to archive the backup on modern hardware. The save set condenses the disk to it's minimal file size, and on restore you get a "fresh" copy with contiguous files. The basic incantation is: $init DKA200 volnam /nohigh $backup/image/verify DKA300: DKA200:filename.sav/save It's best practice to fix up any lint on the disk prior to backing up / archiving it, i.e. to resolve any block allocation / file index inconcistencies: $analyse/disk DKA300: -- generates a list of issues $analyse/disk/repair DKA300: -- lists and fixes any issues $analyse/disk/read DKA300: -- reads all the blocks and tells you which ones have irrecoverable parity errors With three spindles on a system you can produce a compact copy of a disk image, with the file index at the beginning rather than the centre of the disk. One spindle runs the system and backup, another disk (which could also be the system disk) has a saveset copy of the imaged disk on it, the final disk will be initialised and have the saveset written to it. $initialise dkb000 /index=beginning/nohighwater $mou/foreign dkb000: $backup/image/verify/noinitialise dka200:filename.sav/save dkb000: The reason for doing this used to be to produce the smallest possible "necessary" disk image for burning on a CD or whatever. Nowadays, I would probably copy the entire disk - GigaBytes are cheap, ensuring you have copied to the HWM can be expensive. Obviously, a live disk volume should have the file index in its default location at the centre of the disk. IIRC there are/were some (free) SalesWare utilities which permit Files-11 disks to be mounted on XP and read. This would provide a much neater (and safer) way of eliciting the .sav (save set) file for archival on a PC than croping an image at it's high water mark. However, dd of the entire disk containing the savesets may be even better. Regards Martin

17 years, 4 months

27256 in place of a 2764

by dgriffi＠cs.csubak.edu

Under what conditions can a 27256 -- David Griffith dgriffi at cs.csubak.edu A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

17 years, 4 months

Ladder-shaped belt

by mike＠brickfieldspark.org

Is the ladder belt a belt or a chain ? I have seen metal chains in the "ladder" format, each "rung" looped to the next, could be extended or shortened very easily, used to be used on model cars a lot for the four wheel drive. HPC Gears have plastic ladder chain http://www.hpcgears.com/newpdf/ladder_chain.pdf and plastic chain http://www.hpcgears.com/newpdf/ladder_chain.pdf is that the sort of thing ? Mike > ------------------------------ > > Message: 20 > Date: Sun, 27 Jan 2008 11:08:45 +0000 > From: Gordon JC Pearce <gordonjcp at gjcp.net> > Subject: Ladder-shaped belt > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <1201432125.7318.13.camel at elric> > Content-Type: text/plain > > > On Sat, 2008-01-26 at 22:13 +0000, Tony Duell wrote: > >> The drive belt fro an HP9871 (daiswheel printer, the belt is about 2m >> long and looks like a ladder. I am told none have survived. This is one >> printer I would love to find, just to see if I can work out some >> alternative) > > I'm guessing that the rungs of the ladder go between teeth on the > pulleys, and the rails of the ladder keep the belt in place? In which > case, I'd get the closest matching toothed belt I could find and fit > little metal end cheeks on the pulleys to stop it sliding sideways. If > you were tight for space, you could probably get away with only one > pulley. > > Gordon > >

17 years, 4 months

the non-existence of printer collectors

by cclist＠sydex.com

> Date: Sun, 27 Jan 2008 19:59:30 -0700 > From: Richard <legalize at xmission.com> > I knew a guy that wrote an "alarm" program. He would be there late > at night working on the LA-36. When he felt sleepy, he would run his > alarm program. It would move the carraige on the LA-36 to column 132 and > wait. At the requested time it would beep several times. If you didn't > press return, it would print a carraige return, bringing the print head to > the left hand margin again. He would sleep with his hand in the printing > area and if the beep didn't wake him up, the print head slamming into his > hand would do it :-). On that Diablo dot-matrix, it wouldn't just wake him up, it'd probably send him to the ER with some fractures. I think the carriage servo was run from either 48 or 24VDC. I've still got a spare from a Durango printer (same design people). It's basically a 48v Litton Clifton PM DC motor with an attached encoder. I was told that it cost more than the rest of the mechanicals on the printer combined. The other odd thing with the Diablo was that it used several early Rockwell MPUs (at least more than one). PPS-8 or PPS-4, perhaps? I remember seeing and using a really oddball printer in the early 70's from Singer-Friden. It used a disc type element oriented vertically and perpendicular to the paper surface, a leadscrew for advancing the carriage and a big honking spring for carriage return. The type element was inked by means of a felt pad (no ribbon) and tended to leave nice vertical ink stains on the paper when not printing. Very similar to that used on the Singer-Friden 115x calculators, but scaled up for 14" tractor-feed paper: http://www.oldcalculatormuseum.com/friden1152.html When the project shut down, the call came down for the lot to be scrapped, but a co-worker arranged for one to "disappear" off the loading dock. I don't know if he ever pressed it into use. Cheers, Chuck

17 years, 4 months

Fast 8Kx2 ROM replacement

by cclist＠sydex.com

I don't have the message archives, but I don't think that anyone mentioned the Cypress CY22016L NVSRAM using QuantumTrap technology. Pretty cool stuff; very fast SRAM backed by NV RAM; at power-up, the SRAM is loaded from the nonvolatile store; at power-down, it's written (optionally and probably not needed for this application). The "juice" for the optional write-back on power-down is guaranteed by at least a 68 uF capacitor. The SRAM has access times of 25, 35 or 45 nsec. and unlimited writes. The NV RAM is guaranteed for 1,000,000 writes. It's a 5V part and comes in a 28-pin SOIC, so it'd fit nicely on a small PCB that'd fit the outline of a 24 pin PDIP. Here's the datasheet: http://download.cypress.com.edgesuite.net/design_resources/datasheets/ contents/cy22e016l_8.pdf This family comes in sizes ranging from the 2Kx8 just mentioned to a 512Kx8/256Kx16 item. Cheers, Chuck

17 years, 4 months

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test-drb January 2008