test-drb September 2008

test-drb@ccmp.vtda.org

220 participants
323 discussions

HOWTO: Connecting an IBM LPFK to a USB port

by classiccmp＠philpem.me.uk

Hi guys, I've just finished testing my fully assembled (i.e. intended-to-be-permanent) LPFK-to-USB cable. It uses an FTDI TTL-232R USB-to-RS232/TTL converter, a MAX232 level translator, five 0.1uF 0805-size surface-mount ceramic capacitors, a BC547 transistor (well, actually the SMD variant, the BC857), a 4k7 0805 SMD resistor, an 8-pin Mini-DIN plug... and a plastic Maxim/Dallas Semiconductor antistatic box. I did end up using a bit of copper tape and superglue as well (to hold the 4k7 and BC857 on the body of the MAX232)... First problem: if the connector is assembled as recommended by the manufacturer, it's too big to fit in the LPFK's rather small connector port. The solution to this is simple -- ditch the thick (2mm on my connector) rubberised outer cover and use heatshrink instead. As long as you're quick, the plastic inner support won't melt, but assembly is pretty much one-way. It's not easy to assemble, fairly easy to cut apart again, but $DEITY help you when you need to put it back together again. Six wires to desolder, *then* you can put the heatshrink back on. Thankfully properly-soldered mini-DIN connectors are usually quite reliable... Next problem is that the LPFK speaks 12V RS232, while the TTL-232R uses TTL-form inverted RS232. Another easy solution -- put a MAX232 between the LPFK and the TTL-232R to bump the levels. I also added a transistor and a 4k7 resistor to toggle the LPFK's reset line from the serial port's RTS output. That means that when the PC is idle, the LPFK is held in reset, and when the port is open the LPFK is released from reset. Advantage being that if you manage to crash the LPFK, you just need to toggle RTS and wait a few seconds for the LPFK to restart. It does tend to blink a few times when the USB drivers pick up the cable, but only on Windows. Maybe it's the software for my mobile phone trying to pick up a serial cable (despite the fact my phone connects over USB.. natch). I couldn't find any small plastic cases in my junk box, so I used an empty Maxim/Dallas antistatic plastic box. As in, the little clear plastic boxes that hold the parts they send out as free samples. These are small, relatively tough (though a bit thin) and ideal for small projects. Speaking frankly, I'd much rather have unclipped a ferrite EMI bead from a USB cable and used that, but the only ones I could find were moulded onto the cable. Shame, they were a perfect fit. Lastly, I had to reprogram the TTL-232's descriptor table so it claimed the full 500mA of current from the PC. Unplugging the cable from the LPFK will allow the TTL-232 (and MAX232) to start up and enumerate, then you can use FTDI's MProg tool to reprogram the power consumption descriptor (and the description strings too, if you like). Some USB chipsets / motherboards / etc. are more fussy about power consumption than others. 99.5% of the machines I've used seem to ignore the USB port's power consumption unless you short it out, in which case the machine tends to reboot in short order... I've also got an LPFK driver library that works with the USB cable, but should also work with a standard serial cable. You can grab the source code from <http://hg.philpem.me.uk/liblpfk/>, and it should work on any OS that supports POSIX serial communications (that would be Linux, OSX, the BSDs and most of the other Unices, and possibly QNX and Slowlaris - sorry, Solaris - as well). Porting to Win32 is left as an exercise to the reader. The library can do LED setting in both cached and uncached modes (translation: you can change one LED's state and have the LPFK update immediately, or change a dozen at the same time). Key processing is done with an lpfk_read() function that returns LPFK_E_NO_KEY if no keys have been pressed recently, or alternatively returns the first key code in the serial FIFO buffer. Thanks, -- Phil. classiccmp at philpem.me.uk http://www.philpem.me.uk/

17 years

Tube machine restoration (was Schematics of Atanasoff-Berry Computer logic circuits?)

by aek＠bitsavers.org

>> Does the CHM have a complete 'large'-category tube system that could >> conceivably be made to run again? > > Al? Not really. Johnniac, WISC, and the G15 are the closest to being complete but none would be a restoration candidate since current CHM restoration guidelines state that a restoration would not occur if a machine is one of a kind, or there is only one in the collection (G15).

17 years

Slightly OT: SR-52 Service manual

by hp-fix＠xs4all.nl

_____ I'm bussy restoring a Ti SR-52 and having some trouble with the card reader electronics. I't's reading prerecorded cards fine, but is not writing data on the cards . And it does not transport the card fully through the card reader, I have to pull the card the last few millimeters before it gets free from the capstand. So I'm searching for a schematic diagram or service manual. -Rik

17 years

sears wire recorder

by cbritt＠cfl.rr.com

Hi Am attempting to visit your on line page and contact you thru it however I had trouble connecting to you in there so am writing thru my email. I have a Sears wire recorder (model 101.771 and needs a small open wire type spring that pushes an actuator when u go from play to rewind. If you have any idea where i might locate such a part I will get a picture of the spring and provide model ect if that would help. ANy information asto where I might buy a spring for the recorder would be much appreciated Thank You Best Regards, Chuck B cnritt at cfl.rr.com

17 years

Computer Automation library floppy images

by aek＠bitsavers.org

There are now about 400 disks from Computer Automation's program library up at http://bitsavers.org/bits/ComputerAutomation/8_imd. They are in imagedisk format, and are all single sided, single density. There are also some 5" floppies, which i'll work on reading this week. Getting all of the paper directories scanned will take a while. Most of the software is for the LSI-4. CHM has very little on this machine, so hardware and software docs would be good to find. Lars has some material on his site. http://www.sdu.se/computer-automation-museum/ Hopefully this will prompt his donors to find the other LSI-4 docs that they have in storage.

17 years

ENIAC vs. ENIAC-on-a-Chip IC implementation

by gerhard.kreuzer＠liftoff.at

Hi William, thanks a lot. I found the book noted at the page of Jan van der Spiegeln, who did the project years ago. He tell me the ISBN, but I will see, whats Google offer me. Thanks a lot Gerhard

17 years

Need cc:Mail Automatic Directory Exchange Release 2 ($$$)

by sellam＠vintagetech.com

I have a new bounty out. I am looking for cc:Mail Automatic Directory Exchange Release 2, specifically I need the Administrator's Guide. If you have this then please contact me for details. Thanks! -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org [ Old computing resources for business || Buy/Sell/Trade Vintage Computers ] [ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]

17 years

vac tubes / was Re: Schematics of Atanasoff-Berry

by wbblair3＠yahoo.com

Brent Hilpert wrote: > It has occurred to me that if one were setting out to build > a (small?) tube > computer today for fun, to look into selecting the primary > tube(s) from that > class; the question being if one would do any better than > just using > duo-triodes, which are in higher demand. That's exactly what I'm doing. The advantage of going with tubes currently used for audio is that they are still in production, mostly in China and Russia. The disadvantage is that they cost quite a bit more. For small projects like mine, I have no worries about the availability of tubes that are no longer produced. For that matter, I suspect that even very large projects wouldn't have problems with tube availability considering how many of these out of production tubes are apparently still around. For instance, I can buy OOP 5BK7A dual triodes for US$0.78 each (I have ten on hand) or OOP 4BS8 dual triodes (to be purchased on my next order) for $0.38 each. The 5BK7A has a 4.7V heater and the 4BS8 a 4.5V heater. Either of these would work fine at 5V being outside of the typical filament voltage +/-10% rating only very slightly in the case of the 4BS8. For a power supply, I plan to use a modified PC power supply. I have three used, unmodified ones just sitting around from previous PC builds: http://web2.murraystate.edu/andy.batts/ps/powersupply.htm The +12V will be used for the B+ and the +5V for the filaments. Both +12V and -12V could be used for the plate voltage giving a total of 24V as long as the project is small enough to not exceed the 500mA rating (in my case) of the PC power supply -12V output. And, of course, the modified PC power supply will be useful for other projects, too. I've got several homemade variable DC supplies, but they are all limited to 1.5A output which would be exceeded with just three 5BK7A filaments @ 600mA each.

17 years

WANTED: AIM-65 PASCAL and/or PL/65 ROMs

by dm561＠torfree.net

>Date: Tue, 2 Sep 2008 14:22:52 -0700 (PDT) >From: steven stengel <tosteve at yahoo.com> >Subject: WANTED: AIM-65 PASCAL and/or PL/65 ROMs >Please let me know if anyone can send me the AIM-65 PASCAL and/or PL/65 ROMs. >Either originals or copies. >Thanks- >Steve. -------------------------- Didn't know there's a PASCAL, but PL/65, FORTH etc. docs and binaries at: http://highgate.comm.sfu.ca/~rcini/systems.htm m

17 years

IBM 5150 rom: 5700051 at U33 - anyone have this?

by jzg22＠drexel.edu

I'm looking for a specific rom for an IBM 5150 machine: rom 5700051 at location U33. This rom was only used on the very earliest (16-64k MB) 5150 machines. I know Rich Cini has a disassembly of it on his site: http://highgate.comm.sfu.ca/~rcini/classiccmp/files/PCBios.ASM but does anyone have the original binary image? It can easily be dumped from a working 5150 using a dos boot diskette and the instructions at http://mess.toseciso.org/dumping:dump_bios_using_debug/ The actual chip is an MK36xxx rom, which requires a pulse train on /CE in order to read properly. Some eprom programmers will not read these correctly at all, the first byte will fill the entire rom image because the address is never re-latched. (MK36xxx roms will not read properly without a pulse train of HIGH LOW <read data bus then set next address> HIGH LOW <read data bus then set next address>, etc. IBM loved to use these, for some reason, and only switched to real 2364/23256/2764/27256/etc on the ps/2 machines and the later ATs, and on certain expansion cards such as the Xebec hdd controller on the XT,which uses a 2764 for the z80 rom.) The chip can be read in an incompatible eprom programmer by sticking the chip in some solderless breadboard and wiring it to the rom socket in the following way: programmer A0 through an inverter(7404 will work fine) and connecting to rom /CE programmer A1 to rom A0 programmer A2 to rom A1 etc. Data lines connect directly. read the rom as a 27128, then toss the first(0x00), third(0x02), and every odd(0x0x where x is even) byte thereafter, and keep the rest. other than the /CE change, the mk36xxx is pinout compatible to a 2364, which has a different pinout than a 2764 or 27128 does: +--------------+ A7 |1 +--+ 24| Vcc A6 |2 23| A8 A5 |3 22| A9 A4 |4 21| A12 A3 |5 20| /CE A2 |6 2364 19| A10 A1 |7 18| A11 A0 |8 17| D7 D0 |9 16| D6 D1 |10 15| D5 D2 |11 14| D4 Vss |12 13| D3 +--------------+ P.S. does anyone have an IBM 5100 or other machine in the pre-PC 51xx series? I'm looking for info from those, too. Thanks! -- Jonathan Gevaryahu jgevaryahu(@t)hotmail(d0t)com jzg22(@t)drexel(d0t)edu

17 years

← Newer
1
...
25
26
27
28
29
30
31
32
33
Older →

Jump to page:

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

test-drb September 2008