e.tedeschi wrote: Oops, that is good to know. I did a web search of the company name (zebra systems, Inc. ???) and found it listed at another site as a supplier of ZX81 kits. There is no reason the kits won't work anywhere in the world as long as the input to the external power supply is compatible with local power. Also, the back of my mind says that when I checked their site last night, they did say no overseas shipping. If you like, I can find out how much it costs to ship one to the UK and let you know what the total cost would be. They state shipping is $10 for the first unit, and $5 for each additional unit. So you would be looking at $30 for the kit, $7.50 for shipping here ($10 + $5 = $15/2 = $7.50), plus shipping to the UK.

Marvin wrote: Don?t worry about the different scanning rates - they are not all that different. The PAL picture uses 625lines and 25frames/sec = 15625Hz line frequency, the NTSC picture has 525lines and 30frames/sec = 15750Hz line frequency. The ZX-81 output is Black and White only and my experience is that most B/W TV sets and even many Colour sets will quite happily display any B/W picture without problems. On the other hand there could be a problem with the modulator RF channel output (UK=UHF, US=VHF) so the TUNER in a foreign TV might not receive the signal. The main differences (PAL vs. NTSC) are how these systems handle colour and the sound is also not compatible, there are even some regional variations in sound transmissions within the PAL areas. I assembled my ZX-81 kit in 1981 but unfortunately I modified (read: ruined) it later by adding a battery backup/8KRAM of my own design when using it as an EPROM programmer, it still works though! I would really like to buy a new kit from Zebra Systems, but they say they don't supply overseas - well there must be some way around that. Best regards, ??rhallur.

(Sorry for the message on a dead thread - i've been catching up on an e-mail backlog.) I ordered two of the ZX81 kits from Zebra Systems in January - one to relive the ZX81 building experience (with a better soldering iron than I had 15 years ago), and one to keep around in kit form. I received the kits about 2 weeks after I placed the order. The ZX81 kits from Zebra are early (issue 1) releases of the ZX81, and include a UHF RF modulator. Video format is selectable between NTSC, PAL, and SECAM by changing a few resistors. There are different connections for the RF modulator marked marked USA, UK, and Fr on the board; however, the assembly instructions say to ignore these and connect the modulator to the UK and Fr connections. The RF output is approximately on UHF channel 33 in the US. In the Sinclair minimal cost tradition, the RF modulator is not crystal controlled and the output frequency tends to drift - a television tuner with adjustable fine tuning is a good thing to have. Alternately, you can pick off composite video before the RF modulator and use it to drive a monitor. Although the ZX81's video output is not particularly well suited for driving a 75 or 300 Ohm load, the picture is usable, and the addition of a single-transistor amplifier stage for impedance matching can provide reasonable composite video output. The supplied power supply has a 110 VAC input and outputs 9 VDC at 1A, so finding a replacement power supply for your local AC line voltage shouldn't be much of a problem. Zebra (or the tech school that Zebra bought the kits from) supplies their own instructions, which are geared towards assemblers in the US. The Sinclair instructions are not included. Assemblers in countries that use non-NTSC video standards will need to look at the schematic to determine the correct positions of a few resistors. Fortunately, the schematic diagram is included. The two books that are included with the kit ("BASIC Basics" and "Basic Basics of Basic BASIC", or something like that) aren't (in my opinion) useful for much other than pointing out some of the peculiarities of Sinclair BASIC. ZX81 kits were available in the USA by mail order ($149 kit, $199 assembled, IIRC) for about a year before Timex started selling assembled T/S 1000 machines here. Some other Sinclair-branded machines were sold in the US as well; I have US-spec ZX80, ZX81, and QL machines. The machines (that I know of) that were sold by Timex are as follows: Timex/Sinclair 1000 - 2K RAM version of the ZX81 Timex/Sinclair 1500 - 16K RAM version of the ZX81 in a rubber-key Spectrum case Timex/Sinclair 2068 - Enhanced 48K Spectrum with 3-voice sound, extended video modes, some weird bank switching logic, a cartridge port, and a joystick interface. Plastic keys and a space bar. Some of Timex's improvements supposedly made their way into the 128K Spectrum. There was also supposedly a Timex/Sinclair 2048 (not the same as the Timex Computer 2048), which, I assume, was a 2068 with less memory or fewer features. -- Scott Ware s-ware(a)nwu.edu

A friend of mine just acquired a Kaypro Robie. Anyone know anything about this computer as far as how common it was? Also has anyone heard of Drivetec drives? Thanks.

At 10:26 PM 8/30/97 -0700, Don wrote: Don, A small nit to pick, but _all_ 3.5" floppies are 135 tracks/inch. This is true from my SSSD 200K Tandy Portable Disk Drive 2 for my Tandy 200, all the way up to 2.88Meg 3.5" floppy drives. As far as I know, there weren't any (or at least not many) 1.44Meg 5.25" drives ever built, so I am assuming you were referring to the 3.5" floppy drive when you listed the later size. HTH, "Merch" -- Roger Merchberger | If at first you don't succeed, Programmer, NorthernWay | nuclear warhead disarmament should *not* zmerch(a)northernway.net | be your first career choice.

At 05:02 PM 8/31/97 -0700, you wrote: Don, You are certainly correct in that the 1.2Meg 5.25" floppies (and the 720K 80 track 5.25" drives as well) are 96 TPI. However, I would really like to see the specifications on a 3.5" drive that's 96TPI, as I have owned nearly 30 of these drives, from 200K SSSD up to 2.88Meg DSED, and all that I've ever owned, seen, or even heard of are all 135TPI. As well, all standard 3.5" media is 135TPI, and I have successfully formatted and used HD media in my Tandy Portable Disk Drive 2. (they work wonderfully, might I add. If you're quoting a non-standard drive/media, you've surely stumbled upon a rare beast indeed! HTH, Roger Merchberger -- Roger Merchberger | If at first you don't succeed, Programmer, NorthernWay | nuclear warhead disarmament should *not* zmerch(a)northernway.net | be your first career choice.

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While picking up most of the Burroughs manuals I posted about earlier, I had mentioned to the woman that I was also looking for punched cards. Today she found some "IBM" cards with "Leo Computers, LTD" on them! I have probably about 30 of them now and they will make another neat addition to the collection! Again, I picked up most of the Burroughs manuals including the ones marked "Company Confidential". She talked with a friend of hers who worked there who said it was okay to take them. Apparently they were marked that way only for competitive reasons and those reasons no longer apply :)! Her friend who wanted to look at the IBM stuff will be here Thursday and she will let me know then about the stuff. Most likely it will all be available. When I get it, I'll post a list of what is there and it will be available for the cost of shipping.

Among the things I saw were some small data processing cards that are slightly bigger than a third of a regular IBM card. Anyone know what these things were used in? Thanks.

Tim Shoppa wrote: Thanks for the lead! These have "Globe 344" at the bottom but no other written identification. At the top are four columns of numbers 1-32, 33-64, 65-96, 97-132 at about 1/4" spacing. There are three additional rows of numbers 1-32, 33-64, 65-96 at about 1/2" spacing below the other numbers. Along both sides going up from the last rows are the numbers 1,2,4,8,A,B. These could well be the cards described in Doug's web page but I can't tell for sure.

James Willing wrote: Thanks Jim, that is them! They sure make neat bookmarks :).

At 04:29 PM 9/1/97 -0700, Marvin wrote: They were introduced (as I recall) as the card format for the "System 3" line of computers, and also were used as the reciepts in a line of ATM machines that IBM made. Have a few myself, and will be adding an image on my web page shortly... -jim --- jimw(a)agora.rdrop.com The Computer Garage - http://www.rdrop.com/~jimw Computer Garage Fax - (503) 646-0174

Hi Marvin: Any word on those boxes of "IBM 1620" cards? Kevin At 01:53 PM 97/09/01 -0700, you wrote: --- Kevin McQuiggin VE7ZD mcquiggi(a)sfu.ca

On Mon, 1 Sep 1997, Roger Merchberger wrote: You are correct, I erred! The 3.5" diskettes are at a higher tpi. There simply is not a sufficiently large window in the disk housing to access 80 tracks at 96tpi. Sorry! - don donm(a)cts.com *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* Don Maslin - Keeper of the Dina-SIG CP/M System Disk Archives Chairman, Dina-SIG of the San Diego Computer Society Clinging tenaciously to the trailing edge of technology. Sysop - Elephant's Graveyard (CP/M) - 619-454-8412 *--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--* see old system support at http://www.psyber.com/~tcj