test-drb January 2008

test-drb@ccmp.vtda.org

221 participants
430 discussions

by cclist＠sydex.com

> Date: Fri, 25 Jan 2008 16:40:09 -0600 > From: Jim Leonard <trixter at oldskool.org> > Yes. In fact, myself and a few others have done significant work trying > to get CGA properly emulated (composite CGA emulation is pretty damn close > to the original; some tweaked modes work as well). It can even boot > bootable diskette images (as long as copy protection is absent). ...and that's just the problem here. The program diskette is copy- protected. What what, I'm not sure. Cheers, Chuck

16 years, 11 months

Subject: RE: Subject: Re: div by 10 on Z80

by cclist＠sydex.com

> Date: Tue, 22 Jan 2008 19:33:15 -0800 > From: dwight elvey <dkelvey at hotmail.com> > Here goes with using your idea to double use the a register. Except > If I start it with 2, I can use the carry instead of the sign bit. What > fun! > > Div10: > ld a,#2 > ld de,#-640d > divloop: > add hl,de > jr c, div1 > sbc hl,de > div1: > rl a > jr nc,divloop > add hl,hl > ret Ah, but you forgot the add hl,hl to shift the dividend after each iteration. Put it at the top of the loop so it doesn't interfere with the operation of the "rl a/jr nc" pair and scale your divisor by an additional power of 2 and you should have it. By now, we've probably bored the hardware guys to tears and DEC people are tearing out their hair, so we should probably drop the subject. My apologies, but I've always found bit-twiddling fun. It seems that every platform has some peculiar characteristic that can be exploited to good advantage. Cheers, Chuck

16 years, 11 months

Ribbons for your teletype model 43 on ebay

by legalize＠xmission.com

I purchased two from the guy. They are NOS and the ribbon hasn't dried out. He apparently has a bunch of them. He's selling them for $15 each, but he will combine shipping if you buy more than one. I tried to arrange a discount for buying 5, but he was firm in his pricing. So I bought 2. I figure that if I use them both up, I can try my hand at re-inking the ribbon. At $75 for 5 ribbons, that was more than I paid for the terminal itself :-). -- "The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download <http://www.xmission.com/~legalize/book/download/index.html> Legalize Adulthood! <http://blogs.xmission.com/legalize/>

16 years, 11 months

2716 with 100 nS access time ?

by jos.mar＠bluewin.ch

I need a programmable device, with the standard 24 pin layout, with 100nS acces time. 2716's are 350ns to 450ns, 2816's are 150nS match. What other options do I have ? ( Target : replace some bipolar microcode proms So I can experiment a bit) Jos

16 years, 11 months

Dead IBM PC 5150 motherboard - help troubleshooting

by richard.beaudry＠gmail.com

Hello all, I have an IBM PC, 5150, 16-64KB motherboard, that appears to be dead. Power on produces no display or disk activity (even after a while), and no beeps >from the speaker (I tried a couple of speakers, so I don't think it is a speaker issue. >From what docs I found on the internet, the switches are set up properly for the machine's configuration... I am pretty sure the motherboard is getting power. I checked at a RAM socket, and all voltages were there, and well within specifications. The problem is, I'm not sure where to go from here. I have NO schematics, and haven't ever troubleshot a 5150 before. I DO have a good meter, and a scope (and I know how to use it!) What would be the first things to check? Thanks for any help!!! Rich B.

16 years, 11 months

2716 with 100 nS access time ?

by ajp166＠bellatlantic.net

> >Subject: 2716 with 100 nS access time ? > From: Jos Dreesen / Marian Capel <jos.mar at bluewin.ch> > Date: Fri, 25 Jan 2008 21:11:26 +0100 > To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> > >I need a programmable device, with the standard 24 pin layout, with 100nS acces time. >2716's are 350ns to 450ns, 2816's are 150nS match. >What other options do I have ? > >( Target : replace some bipolar microcode proms So I can experiment a bit) > > Jos The only way you can get to under 100ns is using larger EEproms or Eproms as their smaller feature size made them faster. You can get 27256s under 100ns (might be cmos but no matter) and larger parts go down to under 50ns. Ofcourse that means a chip adaptor but thats no big deal. Allison

16 years, 11 months

UK assistance requested

by jfoust＠threedee.com

At 01:16 PM 1/25/2008, from at fu3.org wrote: >2008/1/25, Chuck Guzis <cclist at sydex.com>: >> trying to get an old PC program (on 3.5" media) going on his >> modern PC system. He's run into one of the copy-protection schemes >> that worked fine under MS-DOS but not under 2K or XP. > >DOSBox sends its regards. Yes, it's great for reviving old programs under contemporary Windows. http://en.wikipedia.org/wiki/DOSBox , at http://www.dosbox.com/. - John

16 years, 11 months

Z80 Divide by 10

by cclist＠sydex.com

From: dwight elvey: Well, you've got me confused. HL = dividend (Dnd) > ld d,h > ld e,l ; DE=Dnd > add hl,hl ; HL=Dnd*2 > add hl,hl ; HL=Dnd*4 > add hl,de ; HL=Dnd*5 > add hl,hl ; HL=Dnd*10 > ld b,h > ld c,l ; BC=Dnd*10 > add hl,hl ; HL=Dnd*20 > add hl,hl ; HL=Dnd*40 > add hl,bc ; HL=Dnd*50 > add hl,de ; HL=Dnd*51 ; At this point, HL=0-41000 > ld a,h ; A=HIGH(Dnd*51) > rra ; A=HIGH(Dnd*51)2 > ld l,a ; L=HIGH(Dnd*51)/2 ; At this point, you've lost me. But a non TLU fall-through 10-bit divide with only one conditional branch at the end would be worth a paper in CALGO, surely. Cheers, Chuck

16 years, 11 months

Ohio Scientific

by djg＠pdp8.net

I'm working on getting my Ohio Scientific Challenger II running. The system is a 505 CPU (first rev that doesn't match schematics online), 535 memory 48k (no schematics online I have found), 540B video card with color and dual 8" floppy. This machine was modified with a switch so I can use either the video board or a serial terminal. Its pretty close to the system I first used in high school. I think I have the computer working but would like to run a memory test. Does anyone know of one available that I could load in through the monitor? Or do I need to see how much 6502 I can remember from 25 years ago? The video card generates the first line right after end of vertical blank so all my monitors cut off most of the first line. Is this normal? Next is moving on to the the 8" floppies. After I get them working I want to dump all the disks I have. I found at osiweb a program to dump floppies but it was for 5 1/4". Does anybody know of one that will dump the 8"? Perferably in a format that an emulator can use so I can verify the dumped disks are good.

16 years, 11 months

Link: IBM's anti-MacBook Air goes up for sale on eBay

by lproven＠gmail.com

http://www.reghardware.co.uk/2008/01/25/ibm_5155_up_for_sale/ Quote: [ Forgotten Tech Want to own a piece of portable computing history? Actually, we use the word 'portable' advisedly - we're talking an IBM 5155 here, a 30lb (13.6kg) monster that, as the eBayer offering it up to the highest bidder admits, "is not a MacBook Air". ] Amusing, even affectionate, story and indeed auction description, too. -- Liam Proven ? Profile: http://www.linkedin.com/in/liamproven Email: lproven at cix.co.uk ? GMail/GoogleTalk/Orkut: lproven at gmail.com Tel: +44 20-8685-0498 ? Cell: +44 7939-087884 ? Fax: + 44 870-9151419 AOL/AIM/iChat: liamproven at aol.com ? MSN/Messenger: lproven at hotmail.com Yahoo: liamproven at yahoo.co.uk ? Skype: liamproven ? ICQ: 73187508

16 years, 11 months

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test-drb January 2008