test-drb December 2015

test-drb@ccmp.vtda.org

191 participants
268 discussions

by kspt.tor＠gmail.com

On 20 December 2015 at 07:25, Eric Smith <spacewar at gmail.com> wrote: >> Is this it? (1983) >> http://www.pestingers.net/PDFs/Other_computers/IEEE%20696%20S-100%20Bus%20S… > > That's the one that's been screwed up by OCR. What about this one? Except for the front page and possibly the very beginning, it seems to be the same document, but different. If it's any better I'm not sure about, some pictures didn't do too well in the scan, apparently. http://www.imsai.net/download/IEEE_696_1983.pdf

8 years, 7 months

What did computers without screens do?

by jnc＠mercury.lcs.mit.edu

> From: Mike > The one question I do have for the older gentlemen on here is what in > the world did the computers without a screen to look at do? There are a number of different generations, and the way they were used generally depended on what the computer in question had for I/O capabilities. In the very earliest machines, the computations tended to be mathematical modeling; things that needed a lot of computing, but had very modest I/O requirements. The classic example was the hydrogen bomb calculations performed on ENIAC (which was originally built to do ballistics computations), but other similar ones included structural modeling, etc. That class of application continued (and does so, to this day), but over time, more and more things got done using computers, as their capabilities (online storage, I/O, etc) grew. In general, the new applications were added to the existing ones, but did not supplant the earlier ones. Starting with a computer in England called LEO: https://en.wikipedia.org/wiki/LEO_(computer) they were also applied to business applications (inventory, payroll, billing, etc), which typically did more modest computations, but more I/O, which required better I/O capability (cards, tapes, printers, etc). With the advent of timesharing in the early 1960's, it became common to add individual character-output terminals (initially printing, moving mostly to video terminals circa the mid-70's), and with the ability of users to interact with applications running on a computer, applications broadened even further; online text preparation was one common one. The final phase came with the introduction of bit-mapped video terminals, which allowed the interactive users to use graphics, and images; the very earliest such systems were on time-sharing mainframes, but with the growth of personal computers, that technology migrated there (note that the very earlist PC's had only character-output terminals, mimicing their main-frame big brothers of the time). Noel

8 years, 7 months

scan of IEEE-696 standard

by radiotest＠juno.com

At 03:04 PM 12/20/2015, Eric Smith wrote: >The problem has been solved. Is the solution available online? Dale H. Cook, Roanoke/Lynchburg, VA Osborne 1 / Kaypro 4-84 / Kaypro 1 / Amstrad PPC-640 http://plymouthcolony.net/starcity/radios/index.html

8 years, 7 months

scan of IEEE-696 standard

by spacewar＠gmail.com

Does anyone have a scan of the IEEE-696 (S-100) standard that has NOT been run through OCR to screw up the typography (and even some of the illustrations)? I'm *not* looking for the draft, only the final standard.

8 years, 7 months

Gotek floppy emulator w/ HxC firmware

by snhirsch＠gmail.com

Is anyone using this combination? I'm having problems getting it to work reliably on a soft-sector controller in my Heath H89 and their forum is essentially dead. --

8 years, 7 months

WD9000 Pascal Microengine floppy adapter (was Re: WD9000 Pascal microengine schematics available)

by spacewar＠gmail.com

The WD9000 Pascal Microengine main box does not include floppy drives. It can support up to four floppy drives, which can be either 8-inch (500 kbps transfer rate), or 5.25-inch (250 kbps transfer rate), as selected by a DIP switch setting on the WD900 board. Unfortunately the DIP switch directly controls the clock rate into the 1793 FDC chip, so it is not possible to mix 250 kbps and 500 kbps drives. However, it should be possible to mix 8-inch drives with high-density 5.25 inch or 3.5 inch drives that use the 500 Kbps transfer rate. The floppy connector on the back of the WD9000 box (and the WD900 board) uses a DC37S connector, and the pinout seems to be unique to the Pascal Microengine. My Microengines did not come with the floppy drives or cabling. I've designed a simple adapter PCB, and just got the first boards back from PCBWay today. I haven't yet finished assembling one because I screwed up ordering on some of the components and connectors. Photos: https://www.flickr.com/photos/22368471 at N04/albums/72157660580290148 The WD900 board uses an FD1791 double-density floppy controller. It appears that the main board may have been originally intended for the FD1771 single-density controller, as the board revs I've seen don't have a suitable double-density data separator built in. On one of my units, the FD1791 is on a daughterboard with a typical analog data separator design using the WD1691 floppy support logic and a 74LS629 VCO. My other board has the FD1791 on the main board, but has some significant rework to install an SMC FDC9216B digital data separator chip in place of one of the TTL chips originally used by the main board design. I've seen other WD900 boards with the FDC9216B modification, so I think this was rework done at manufacturing time, rather than a field change. One aspect of the floppy controller design seems a bit unusual. The WD controllers have a HLD output used to tell the floppy drive to load the head, and an HLT input (Head Load Timing) to indicate that the head is loaded. After the controller asserts HLD, it waits for HLT to go true before proceeding with read, write, or format operations. A typical 8-inch drive takes 35 ms to load the head, and maybe a few more for head settling. A common way to wire the controller is to use an external one-shot triggered by HLD, with its output wired to HLT, and adjusted for a time delay a little longer than the drive requires for loading the head. 8-inch drives typically can either be jumpered to use a dedicated head load control line on the interface to control the head load solenoid, or to automatically load and unload the head as the drive select signal is asserted and deasserted. Normal 8-inch drives have the head load solenoid to do what was previously described, and run the spindle motor either all the time, or whenever a disk is inserted and the door closed. 5.25-inch drives, and some later 8-inch drives such as the Tandon TM848, do away with the head load solenoid and instead are intended to operate with the spindle motor active only when the drive is selected, or when a motor control signal is active. As such, they don't require any head load time, but instead require a motor startup time that is even longer; the slowest drives require about a second for spinup. With a WD controller, this is also sometimes accomodated by using the one-shot between HLD and HLT. Some WD-based controller designs, such as those in the TRS-80 Model I, III, and 4, are only intended for 5.25-inch drives (or the 8-inch drives that use motor control and no head load solenoid), and tie the READY signal from the drive to the HLT input of the FDC. The WD900 board tries to acommodate these variations by bringing the HLT signal to its DC37S connector, for the system integrator to wire up as desired. The only complete Pascal Microengine system I've seen up close in recent history had a hand-wired drive cable to 8-inch drives, with the HLT signal simply tied to a +5V pin on the same connector. The net effect of that is that the FD1791 asserts HLD, delays 15ms if the h bit of the command is 1, and does not delay any further. Unless the drive can actually load its head that quickly, this doesn't seem ideal, but I suppose it works because the FDC won't be able to read a valid sector address field until the head is loaded. For a write operation, I'd worry that the head might not have fully settled by the time the actual write begins, possibly leading to unreliable writes. To support proper head load or motor spinup timing, I put an optional PIC microcontroller and DIP switch on the adapter, to act as a digital delay between HLD and HLT, with sixteen switch-selectable delays. The drive select lines are wired to PIC inputs, so if desired, firmware could actually use different delays for different drive selects, if you mix drives with different head load timing requirements. I haven't yet written any PIC code for it. The board should basically work as described above with HLT jumpered to +5V, without the PIC and related components installed. The adapter has both a 50-pin connector for 8-inch drives, and a 34-pin connector for 5.25-inch or 3.5-inch drives. It is intended for one connector or the other to be used, but not both. Even if you use a combination of drives that all use the 500 kbps transfer rate, having them cabled separately to the two connectors could result in termination problems. Naturally, only hours after ordering the PCBs I thought of improvements that I'd like to make to the design, but I don't anticipate that there will be a second run of boards. I don't presently have any bootable disk for the Pascal Microengine, so I'm not yet able to test the adapter. However, if anyone else needs such a thing, I have a small number of bare boards that can be made available inexpensively. (I don't have time to assemble boards other than for myself.) If there's any interest, I'll publish the Eagle design files, gerber and excellon files, a PDF of the schematic, and source and object code for the PIC firmware. The firmware will be GPLv3 licensed, and the other design files with be under a Creative Commons license, probably CC BY-SA 4.0.

8 years, 7 months

Wanted: NEC PC-8001A Mini-Disk Module PC-8031A

by todd.george＠gmail.com

Hi there everyone. I'm hunting for an NEC PC-8031A mini-disk module for the NEC PC-8001A computer. I have the computer itself and PC-8012A expansion chassis already. Additionally looking for anything else relating to this computer that you might have kicking around and be willing to part with. Including but not limited to the "Wedge", expansion unit cabling, expansion cards, etc. Note: I have seen the one floating periodically on eBay and am keeping a close eye on eBay in general for this unit so am looking for leads outside of that. If anyone has stuff for this computer, please contact me off-list. I'm near Philadelphia and willing to drive to avoid you having to pack/ship. Not against shipping stuff either. Thanks!! -Todd

8 years, 7 months

IBM Mainframe terminal stuff

by seefriek＠gmail.com

From: Mike Ross <tmfdmike at gmail.com> > I have a 3172 controller; physically rough and needs restoration but *should* work if > I can fake the remote connection and modem - bisync etc. B From: Paul Berger <phb.hfx at gmail.com> > you need a modem eliminator mostly to provide the clocks for the sync data line, > other than that is is similar to a null modem. Not sure if this would work here, but the Cisco IOS "IBM Feature Set" has support for all sorts of weird bisync use cases. I've used it to fake termination of an ALC (Airline Line Control) bisync connection where a modem connection was expected. You can then convert, tunnel or bridge to any number of other strange things. There even exists an IBM channel attach card for the Cisco 7k routers that turns it into the equivalent of a 3172 and/or 3745. KJ

8 years, 7 months

Design tools Was: Mystery IC: Allen Bradley 314B102

by jnc＠mercury.lcs.mit.edu

> From: Brent Hilpert > I need to move to something newer but I haven't evaluated current > schematic-drawing programs Dave Bridgham got me started with KiCAD, and that seems like a pretty good system to me. It has separate sub-systems for schematic capture; circuitry checking; netlist generation; PCB layout; etc, etc. I've only worked with the first three, but it seemed pretty good for them. > I'm a little concerned they won't provide the degree of control or > finesse I like Well, you'll have to try it and see, but it's pretty customizable: they provide libraries of common components, but it has a nice component editor for drawing up new ones (or customizing the ones it comes with). Component location and line routing (in the schematic capture) are manual, but it's grid-based, so things line up. Noel

8 years, 7 months

Help locating a 1975/76 Datanetics Rev B or Rev D keyboard

by applecorey＠optonline.net

I?m looking for an original Datanetics keyboard circa 1975/76 like the one Mike Willegal makes a reproduction for, not the more common Apple ][ datanetics keyboard. I have built one of his reproductions, but I?m looking for an original. http://www.willegal.net/appleii/apple1-datanetics.htm <http://www.willegal.net/appleii/apple1-datanetics.htm> Anyone have one they are willing to part with? Thanks, Corey986

8 years, 7 months

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test-drb December 2015