test-drb August 2005

test-drb@ccmp.vtda.org

227 participants
528 discussions

by GOOI＠oce.nl

> Gooijen, Henk wrote: > > >Hi all, > >I am looking into the possibility to add a floppy disk interface > >to the 6809 Core Board. 20 years ago, so this is OT :-) , I built > >a floppy disk interface for my 6800 system using the 1793. > >I have ordered some 1793 from BG Micro, but checking the data > >sheet of the 1793, I noticed taht the FDC requires +12 on pin #40. > >I know the MB8877 is pin-compatible with the 1793, but does *not* > >need the +12V. > >I failed to locate a seller for the 8877, but I do not know "all" > >major part sellers in the US. JameCo, BG Micro and DigiKey do not > >have this part ... somebody knows a good stock of the 8877 ? > >I can use the 1793, +12V is "ugly", but the voltage is present as > >the +12V is needed for the floppy drive itself! > > > > thanks, > >- Henk, PA8PDP. > > > > > Has it really be the 1793? Or might not be a 2797 design (2797 is > also available from BG micro) from www.swtpc.com/mholley > (New design for SS30 FDC) is more appropriate for "new developments", > given that it doesn't need that really ugly external data separator > logic which always prevented me from building FDC boards (a usable > separator chip is more difficult to find than the FDC chip, and the > alternatives with a TTL-monoflop grave is not even more attractive). > > Actually, what is your real problem? You already have 12V for the > floppy drive, so what prevents you from feeding it into pin #40 of > the 1793? +12V on an otherwise +5V board is not more ugly than a > +25V source on an eprommer board, or +12/-5V for 2708/4116 memory > boards. > > Holger Thanks for the reply Holger. Your remark about the +12 for the FDC // +25 for an EPROM programmer is correct. I know of the existence of the 2797, but have totally none experience with it what-so-ever. The link that you gave is nice, but I am not sure I can *copy* the design ... Further, I have several 1793 here, so that is cheap for me. I would need to buy the 2797 and ship it to The Netherlands (sources here are not as good as in the US). The data separator I use with the 1793 is more stable, and built with a VCO (LS629, LS393 and LS153). I will look into the 2797 a bit more, but I guess I'll go with the 1793. I saw in the diagram of the 2797 that it has also 2 trimpots for the adjustment ... Not sure yet ... thanks, - Henk, PA8PDP.

18 years, 7 months

Fw: TRS-80 floppy drive compatibility (MISSING MESSAGE)

by infomagic＠localisp.com

In issue 54, I received two replies to the message I sent Saturday evening, but my original message was not in any of issues 53, 54, or 55. I have noticed this kind of "disconnect" before, both with my own message and with messages from others. I receive the cctech "daily digest" (often there are many each day), and I send my messages individually from my email client to the cctech at classiccmp.org address. If there is a message board or forum, I am not aware of it. Am I missing something in my communications connections? Are you folks using some other tools or websites? Was my messge deliberately deleted, or has it not arrived in the digest yet? Is this a normal behavior, or a symptom of something I'm not doing right? Thanks for any help you can provide, -John M. -----Original message----- From: infomagic infomagic at localisp.com Date: Sat, 27 Aug 2005 18:46:20 -0400 To: cctech at classiccmp.org Subject: TRS-80 floppy drive compatibility I have a Tandy CoCo that had been used with 2 floppy drives. Can I just unplug the drives and use them with a Model I, III, or IV ?? TIA, -John

18 years, 7 months

does any read punch cards anymore?

by brad＠heeltoe.com

Remember punchcards? Does anyone read them these days? I'm just curious if anyone does, and if they do, how they do it. Someone approached me with some tapes to read and they also had 2 boxes of cards. I remember a nifty desktop card reader attached to a PDP-8/L once. I never used it but it sure seems like it would be easy/fun to wire it up to something more modern. Do small desktop card readers exist anymore? Anyone got one? (I can hear the chorus now - "medication time!" :-) -brad

18 years, 7 months

6800 opcode $02

by ard＠p850ug1.demon.co.uk

Does anyone know what Opcode $02 is on a Motorola 6800 processor. It's not defined in the data sheet, but I have a device which forces that instruction onto the data bus in one of the test modes. Is it, by any chance, the infamous HCF instruction? -tony

18 years, 7 months

Fw: [8bitcomp] Digest Number 317

by geoffreythomas＠onetel.com

Anyone interested in Apple II stuff. Posted on 8-bit comp. website - self evident really. :>) Geoff. ----- Original Message ----- From: <8bitcomp at yahoogroups.com> To: <8bitcomp at yahoogroups.com> Sent: Wednesday, August 31, 2005 5:58 PM Subject: [8bitcomp] Digest Number 317 > ------------------------ Yahoo! Groups Sponsor --------------------~--> > Most low income households are not online. Help bridge the digital divide today! > http://us.click.yahoo.com/cd_AJB/QnQLAA/TtwFAA/5ryolB/TM > --------------------------------------------------------------------~-> > > There is 1 message in this issue. > > Topics in this digest: > > 1. Lots of free Apple II software > From: "genoman45" <genoman45 at yahoo.com> > > > ________________________________________________________________________ > ________________________________________________________________________ > > Message: 1 > Date: Wed, 31 Aug 2005 13:44:29 -0000 > From: "genoman45" <genoman45 at yahoo.com> > Subject: Lots of free Apple II software > > I found a few boxes full of Apple II software in my basement. Most > are in their original packages that remain unopened. Some packages > are open - but all is original software. > > I have no way to check to determine if the software is good. I can > throw it all out or give it away if it still is desired stuff to > someone. I live near Minneapolis. I am also willing to ship it for > the cost of UPS shipping. I guess I have 40 pounds of software and > some cards like the CP/M card and the serial card. They appear to be > in good shape. I do not want to pick through it and will give it all > away or ship it all. In other words, take it all or none - It is free > stuff after all. > > Best Buy started in St. Paul and in their first year or so they bought > out a small computer-electronic shop. That shop had Apple II software > and the new manager wanted to get rid of all of it, so he told me he > would sell it to me for a fixed price. My son, then age 11, sold some > of the software at user meetings and to friends. He did OK with it > and learned a lot about business in the process. But he did not go > through it all and left it in boxes - that is what I found in our > basement. > > Let me know if you are interested. Please put Apple II somewhere in > your email subject line and your phone number would be helpful. > > It is great to see that 8-bit is not completely dead. > > Gene > > genek at yahoo.com > > > > > > > > > > > > > > ________________________________________________________________________ > ________________________________________________________________________ > > > > ------------------------------------------------------------------------ > Yahoo! Groups Links > > <*> To visit your group on the web, go to: > http://groups.yahoo.com/group/8bitcomp/ > > <*> To unsubscribe from this group, send an email to: > 8bitcomp-unsubscribe at yahoogroups.com > > <*> Your use of Yahoo! Groups is subject to: > http://docs.yahoo.com/info/terms/ > > ------------------------------------------------------------------------ > > > > > > > -- > No virus found in this incoming message. > Checked by AVG Anti-Virus. > Version: 7.0.344 / Virus Database: 267.10.18/86 - Release Date: 31/08/05 > > -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.10.18/86 - Release Date: 31/08/05

18 years, 7 months

TD100 delay line chip?

by ajp166＠bellatlantic.net

> >Subject: TD100 delay line chip? > From: Brad Parker <brad at heeltoe.com> > Date: Wed, 31 Aug 2005 16:02:10 -0400 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > > >The question about the ttl oscillator jogged my memory. > >Anyone recognize a line of "delay line" chips with names like TD25, >TD50, TD100, etc... The look they were expensive at the time, like $10 >around 1976. > >The TD100 pinout looks like this: > > +------+ >input | 1 14 | vcc > | 2 13 | > | 3 12 | 20ns >40ns | 4 11 | > | 5 10 | 60s >80ns | 6 9 | >gnd | 7 8 | 100ns > +------+ > >I don't have an exact part number or mfg. (I know where I can find one >but it's not easy and will take some work) > >I want to model these in verilog but I'm not exactly sure how they work. >They are delay lines, but I'm not sure how they react. The input seems >to be a short pulse from high to low of about 40ns. I'm assuming this >produces an approx 40ns pulse after the prescibed delay, but I'm not >entirely sure. > >I would love to see a few pages from a data book which describes how >these react (enough to model them correctly). > >any pointers? Treat it as if it were a transmission line with length N. The rough length for wire is 1ns/ft but if the wire is wound around a grounded metallic form the wire to ground acts like a transmission line and the insulation sets the spacing hence characteristic impedence as well as velocity factor. Allowing for velocity factor the 1ns/ft can be be more like 1.5ns/ft. So winding 30ft of #42 wire is actually compact and a substantial delay. I did a DL for the 16k muxed Drams that way and found I could easily measure the delay and trim the timing very accurately. It was far more stable than RC oneshots (74121/123/9602) it was stable too. During testing I was using rolls of RG174 (50 ohm .125 dia coax with a VF of .66). Turns out that even a 100ft roll was way too long. Bulky but easy to get 15ns (about 117.3 inches) delay accuratly. Allison

18 years, 7 months

TD100 delay line chip?

by dwight.elvey＠amd.com

>From: "Brad Parker" <brad at heeltoe.com> > > >The question about the ttl oscillator jogged my memory. > >Anyone recognize a line of "delay line" chips with names like TD25, >TD50, TD100, etc... The look they were expensive at the time, like $10 >around 1976. > >The TD100 pinout looks like this: > > +------+ >input | 1 14 | vcc > | 2 13 | > | 3 12 | 20ns >40ns | 4 11 | > | 5 10 | 60s >80ns | 6 9 | >gnd | 7 8 | 100ns > +------+ > >I don't have an exact part number or mfg. (I know where I can find one >but it's not easy and will take some work) > >I want to model these in verilog but I'm not exactly sure how they work. >They are delay lines, but I'm not sure how they react. The input seems >to be a short pulse from high to low of about 40ns. I'm assuming this >produces an approx 40ns pulse after the prescibed delay, but I'm not >entirely sure. Hi This is generally true. You can assume that the intent is to delay any edge by the specified time. If the pulse was longer or shorter, it is as though both edges took some time to get to the output pins. For the longer delays, these used actual delay lines, composed of inductance and capacitance. I would assume that in verilog, it was just a # delay. The various taps delay events at the input by the specified amounts. Dwight > >I would love to see a few pages from a data book which describes how >these react (enough to model them correctly). > >any pointers? > >-brad >

18 years, 7 months

TD100 delay line chip?

by leeedavison＠yahoo.co.uk

They're just LC delay lines with schmitt output buffers. Each delay step is a T network with the L component on the arms of the T and the C component to ground. Any signal on the input appears xx nanoseconds later on each of the tap outputs. Lee. ___________________________________________________________ To help you stay safe and secure online, we've developed the all new Yahoo! Security Centre. http://uk.security.yahoo.com

18 years, 7 months

Reading DECtapes (was 1/2" tape cleaner?)

by aek＠bitsavers.org

I think that Al Kossow has lots of experience reading old DECtapes based on the good DecTape archives that he has on bitsavers. Al, can you share a little of your experience and insight with the rest of us? How well do these things hold up 30-35 years later when they are actually being read and written to on a TU56? -- very, very well. The tapes have redundant track encoding, they are pretty low density, and the formulation doesn't stick. I've read tapes from the mid 60's w/o a problem. I have a bit-level reader with custom read amps coming to deal with the couple of marginal tapes and LINCtapes that I have. -- 1/2" tapes, on the other hand, are a total PITA.

18 years, 7 months

Anyone got a plain ASCII Windows font?

by rcini＠optonline.net

All: Does anyone have an ASCII/terminal font for Windows that has only the standard ASCII chars (32-127) which are also replicated at the extended address (i.e., 160-255) instead of the PC OEM graphics chars? I can't find a way to force 7-bit ASCII chars in Tera Term so when I use it with my Altair I frequently get PC graphics characters on the screen. I have a font editing program but you have to edit each character individually. Thanks. Rich Rich Cini Collector of classic computers Build Master for the Altair32 Emulation Project Web site: http://highgate.comm.sfu.ca/~rcini/classiccmp/ /************************************************************/

18 years, 7 months

← Newer
1
2
3
4
5
6
7
8
...
53
Older →

Jump to page:

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 August 2005