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101090 discussions

Are you sure the 6550 is dead? (was: Mos Technology RAM wanted)

by Philip.Belben＠powertech.co.uk

> Yes, I'm sure that's true. The 2114 PETs are rarer, but I can't see any If you used to service the things, I have to take your word for it, but I've seen several with 2114s and I don't think I've seen any with 6550s. Oh well. [...] > Oh, I did that to check that it was definitely the RAM and not anything > else, long before I posted my request. I could fix about anything else on OK, so you are sure that it is the chip that's dead. I still think it's a fault that affects the whole chip... > The PET determines the RAM size by reading and writing a byte in every > block and assumes it has found the top of RAM when it gets an error. It > was just coincidence that one of the 5th pair was the one to go. So I now > have a 7K PET, because I put the faulty IC in the top pair. It reports > 6143 bytes free. I'm afraid I have a minor quibble here. To write a byte to every block would be pointless as a memory diagnostic, although it would indeed find the top of RAM. However, the PET actually writes two test patterns to EVERY BYTE. PETs I've seen with dodgy RAM come up with really strange numbers of bytes free, not just multiples of 256 minus 1. Early PETS like yours (and my first one) leave 36 in each location when they've finished. Goodness knows why. Later PETS seem to be using 01010101 and 10101010 as test patterns, since they leave 170 (decimal) in each location. (As an aside: vintage PET users, on old machines at least, will have come across the corrupted links in the program listing, which instead of pointing to the next line point somewhere silly. The most common crash then is a program listing that just prints $ signs and doesn't respond to the stop key... Can't remember what keyword 170 gives you on the newer machines, though. When I was involved in developing an adventure game for the BBC micro, we typed a lot of the text on an 8032 (can't remember why). 170 ended up as the token for "HA" when we compressed it. Result - a corrupted address made the machine laugh at us. No, this was not intentional!) ********** Expansion box. The old PETs don't AFAIK have the internal expansion connector - they have an edge connector sticking out at one side. Very useful for toggling RESET with a pair of tweezers! That aside, on this edge connector are brought out most of the block select lines from the 74154 I mentioned in my previous post. In particular, brought out are lines 1 to 7, 9, A and B. It takes only three four-input AND gates to re-encode any eight of these you choose into three upper address lines for a 62256. On my PET I used 2 to 7, 9 and A, and got 32K main memory (including the 8K it already had) plus 8K of RAM in ROM space, above the screen memory. My suggestion is: disable the select to the upper 4K of memory within your PET, and encode lines 1 to 7 and 9. This will give you 32K of main memory, several spare 6550s, and 4K of RAM above the screen. Essentially, you will have a 4K PET fully expanded. Power, as always, comes from the second cassette port... Note block select 0 is NOT present on the expansion connector, so you can't readily disable all the internal RAM. Philip. ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept for the presence of computer viruses. Power Technology Centre, Ratcliffe-on-Soar, Nottingham, NG11 0EE, UK Tel: +44 (0)115 936 2000 http://www.powertech.co.uk **********************************************************************

26 years, 1 month

IBM 5150, am I nuts or what?

by SUPRDAVE＠aol.com

In a message dated 3/22/00 4:40:10 AM Eastern Standard Time, mikeford(a)socal.rr.com writes: > I now have a few IBM 5150 Personal Computers, latching on to the nicest > ones today along with I think the correct original keyboards. I have to > wonder if I am not perhaps getting a little dotty in my old age. What the > heck am I going to do with them? > > Anybody else have some? What can they do? > > How about a 5100 (sounded like something I might want to hoard if I see one)? > ive had a 5150 apparently unused in its box for about 2 years now. perfect condition and even has the cardboard shipping disks in its drives! didnt get the documentation though. just recently i found a 5160 in its box as well. its a later model with half height floppy drive. it does have a few cards installed, but machine is extremely clean and no dusty insides. i assume it was purchased as a spare and seldom used, if it ever was. i also have that original pc keyboard with its crappy layout still in its box. DB Young ICQ: 29427634 view the computers of yesteryear at http://members.aol.com/suprdave/classiccmp/museum.htm --You can lead a whore to Vassar, but you can't make her think--

26 years, 1 month

Are you sure the 6550 is dead? (was: Mos Technology RAM wanted)

by pete＠dunnington.u-net.com

On Mar 21, 21:48, Tony Duell wrote: > > else, long before I posted my request. I could fix about anything else on > > the PET, but I draw the line at grinding the top off to poke at individual > > flip-flops in an IC :-) FWIW, the first job I had in > > Really, kids these days..... Well, I once ripped the metal lids off a few ceramic DRAMs to use them as optical image sensors (ISTR an article in BYTE, I think it was, years ago about that), and there's a story about how Ferranti designers determined that a particular ULA design worked perfectly if only you could get at the gates with a microprobe to add a pullup in a certain place, but these SRAMs are plastic and I've run out of fuming nitric acid :-( -- Pete Peter Turnbull Dept. of Computer Science University of York

26 years, 1 month

Are you sure the 6550 is dead? (was: Mos Technology RAM wanted)

by pete＠dunnington.u-net.com

On Mar 21, 23:04, Allison J Parent wrote: > If I knew pinout I could find an industry part that would work save for > pinout or package. No offence, but if I can't get a drop-in replacement, I'd rather leave the original as-is, and build my little expansion board. The idea was to disable internal RAM (and perhaps ROM) and put a decoder on the expansion connector (the old PETs have an internal expansion connector). The expansion would carry up to 32K RAM, and one or more EPROMs holding different versions of BASIC (the original doesn't work properly with IEEE-488 disks and some other devices). Anyway, here's the pinout: MCS6550 1024 x 4 SRAM A0 1 22 Vss (0V) A1 2 21 CS1 A2 3 20 CS2 A3 4 19 ~CS3 A4 5 18 ~CS4 A5 6 17 Vdd (+5V) phi2 7 16 D3 A6 8 15 D2 A7 9 14 D1 A8 10 13 D0 A9 11 12 R/~W -- Pete Peter Turnbull Dept. of Computer Science University of York

26 years, 1 month

Almost free 2-port and 4-port fanouts, IEEE 802.3 compliant, Ethernet Version 1.0 and 2.0 compatible AUIs

by ethan_dicks＠yahoo.com

--- Bill Dawson <whdawson(a)mlynk.com> wrote: > Hello again, > > Well, due to the overwhelming response for these 2-port and 4-port Ehernet > fanouts (actually, none) I'm posting this one more time. Interesting devices if you need one, and quite inexpensive. > Perhaps someone can tell me, on list, why no one on this list has any > interest in these. Maybe everyone is saving their money for iOpeners d8^) I have plenty of vintage networking equipment, but I also have plenty of 10BaseT and 10Base2 transceivers to bring them onto my network. Eventually, I'd like to have a single segment of 10Base5 cable, but just for the antiquity factor. I only have one vampire tap at the moment (on a transceiver that has interchangable media connectors - I have two bases and one actual tap). It's not critical, so as I spot really ancient Ethernet stuff I grab it, but items that are _that_ old don't float by as often as they used to. -ethan ===== Even though my old e-mail address is no longer going to vanish, please note my new public address: erd(a)iname.com The original webpage address is still going away. The permanent home is: http://penguincentral.com/ See http://ohio.voyager.net/ for details. __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com

26 years, 1 month

Are you sure the 6550 is dead? (was: Mos Technology RAM wanted)

by pete＠dunnington.u-net.com

On Mar 21, 23:04, Allison J Parent wrote: > <> Are these single voltage or multiple? 4k? 22pin? sounds like the > <> semi-4600 and NEC D410 parts, a 4k pseudostatic 200ns cycle and access > <> under 120ns. I've got a rat load of upd410s. The moto part number > <> doesn't compute though. > < > <uPD410 is 18-pin 0.3" width, 4k x 1, with one ~CE line (the MOS Technology > <MCS6550 has 2 ~CS and 2 CS lines and it's 0.4" wide). I can't find any > <data on a 4600 but I assume it's similar. > uPD410 .4" 22pin three voltage 4Kx1, seperate din and dout, CE and CS/ three > voltage pseudostatic. replaces Semi-4200 and 4402, fastest version to 80ns > access. (it was a screamer for 1978). Oops, I misread the data book -- you're right of course, uPD410 is .4" -- Pete Peter Turnbull Dept. of Computer Science University of York

26 years, 1 month

Almost free 2-port and 4-port fanouts, IEEE 802.3 compliant, Ethernet Version 1.0 and 2.0 compatible AUIs

by allisonp＠world.std.com

<I don't really see how the fanout units on offer (or my unsuccessful <back-to-back device) could do that -- the termination isn't in the <transceiver or fanout unit, it's a resistor on the end of the cable. < Anyway, it would still only be one termination domain. Or maybe I've <misunderstood what you mean? If you mean my back-to-back transceiver idea <yes, if it had worked, you could use it to split a termination domain into <two, just like a two-port repeater, or a very simple bridge (except a <bridge usually separates collision domains too). Anyone ever heard of a DELNI? Ok, it was an 8 port AUI to AUI with a 9th for AUI to h4000 fat eithernet cable. Popular use was for cobbing 4-7 system together locally if you didn't have the BIG backbone. Logial equivilent of a 8 port hub used for 10bt. Allison

26 years, 1 month

Are you sure the 6550 is dead? (was: Mos Technology RAM wanted)

by allisonp＠world.std.com

<Yes! I just repacked my lidless 4116 chips. I only ever got as far as <cementing slide-mount covers on one and sticking it in an Apple II at the <top of RAM and demonstrating the effect by clearing video RAM then lifting <the lid. Many bits sparkled in when light shone on the chip. Many years ago far away... A bunch of us took the lid off a NEC 4116 and focused an image on to one segment of the matrix and then used a apple as a raster box to play the bits to a matix on the screen. lousy res being 128x128ish and no gray scale but high contrast images under infared light really were discernable. Oh, refresh rate (read rate) was basically the "shutter speed" so really slow scans were quite sensitive. Allison

26 years, 1 month

Are you sure the 6550 is dead? (was: Mos Technology RAM wanted)

by allisonp＠world.std.com

<> Are these single voltage or multiple? 4k? 22pin? sounds like the <> semi-4600 and NEC D410 parts, a 4k pseudostatic 200ns cycle and access <> under 120ns. I've got a rat load of upd410s. The moto part number <> doesn't compute though. < <uPD410 is 18-pin 0.3" width, 4k x 1, with one ~CE line (the MOS Technology <MCS6550 has 2 ~CS and 2 CS lines and it's 0.4" wide). I can't find any <data on a 4600 but I assume it's similar. Oh, you shouldn't ahve done that... ;) First off I worked for NEC Micro during 79-84 time frame... hawking memories, micros and peripherals (mostly I82xx parts) as a product engineer. uPD410 .4" 22pin three voltage 4Kx1, seperate din and dout, CE and CS/ three voltage pseudostatic. replaces Semi-4200 and 4402, fastest version to 80ns access. (it was a screamer for 1978). uPD411 .4" 22pin three voltage 4Kx1, seperate din and dout, CE and CS/ three voltage dynamic. replaces ti4060, intel 2107, fastest version to 200ns Tce access. same pinout as 410. FYI, altair 88-4MCD boards were so poor I pulled the TMS4060 static and used uPD410s to make them static, one cut to disable refresh. Very reliable after that! uPD 414, .3" 4kx1 dynamic upd 416 .3 16kx1 dynamic, industry standard 2101 .4 22pin static 256x4 (5101 is the cmos part) 2102 .3 16pin static seperate IO 1kx1 2111 .3 18 pin static common io 256x4 2114 .3 18 pin 1kx4 static, common io 2147 .3 18pin 4kx4 static, seperate IO 45ns 2149 .3 18 pin 1kx4 static common io (2114) 45ns 2167 .3 20 pin 16kx1 static, 55ns 4104 .3 18pin 4kx1 pseudo static seperate io CE/ (-5 85ns Tacc, 180ns Tcy) uPD421 .4 22pin 1kx8, same as two 2114s logically, (-5 85ns) 443/6508 .3 16 pin static CMOS 1kx1 444/6514 .3 18 pin static cmos 1kx4 (like 2114 in cmos) 445 .6 24pin static cmos 2kx8 with CE2 and CE1/ industry pintout 1 446 .6 24pin static cmos 2kx8 industry pinout 2 449 .6 24pin static cmos 2kx8 industry pinout 3 4016 .6 24 pin static cmos 2kx8 6116 pinout Most of those were industry standard with part numbering differnces. Be glad I didn't pull down my hard cover NEC catalogs. <If you're asking about the 6550 I'm looking for, yes it is single 5V rail, <but it's 1k x 4 and it's not Motorola. In fact, I'm fairly sure no-one bu <MOS Technology made them. If I knew pinout I could find an industry part that would work save for pinout or package. Allison

26 years, 1 month

Apple Network Servers

by owad＠applefritter.com

>::If anybody wants more information, see >::<http://www.applefritter.com/prototypes/deepdish/>. > >Quite interesting. It looks like the ANS300 got its 604/200 from an ANS700. >Can I just rip the chip out of another unit and substitute it, or do I still >need the complete 200MHz board? I really couldn't tell you, but I'll forward you message along to Chuck Goolsbee, the owner, who might be able to help. >I'm also particulary impressed with the Spartan page on your site (for those >in the dark, this was a hardware add-on for the Commodore 64 that turned it >into an Apple II): I thought it was just a hardware emulator, but its feature >set was really greater than the sum of its parts. Fascinating! Thanks! Tom Owad ------------------------------Applefritter------------------------------ Apple Prototypes, Clones, & Hacks - The obscure, unusual, & exceptional. ---------------------<http://www.applefritter.com/>---------------------

26 years, 1 month

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