test-drb March 2000

test-drb@ccmp.vtda.org

150 participants
515 discussions

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

by pete＠dunnington.u-net.com

On Mar 22, 23:56, Tony Duell wrote: > You _honestly_ think that a 22V10 (or whatever) is simpler, cheaper, and > easier to use than a couple of 74LS20s? You know, a 22V10 has 24 pins, > and the 2 74LS20s have 28. That's only 4 more pins to solder. And there's > no requirement to program a chip if you use the '20s. No, but I can make more choices with the 22V10 -- I want to be able to switch ROM sets (between the original on the motherboard and possibly two on the expansion) and RAM sizes and that would need a little more effort with the TTL, because I want to *replace* the 74154, not add to it. -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 9 months

2532 EPROM pin-out

by pete＠dunnington.u-net.com

On Mar 22, 17:32, Bill Sudbrink wrote: > > > Could some kind soul post the pin-out > > > of a 2532 4Kx8 EPROM? > > > > Which one TI or moto or ? > > Egad! They have different pin-outs by manufacturer?!?! There's an "industry-standard" arrangement, and a JEDEC arrangement. TI, almost uniquely, chose the "unusual" one for 2532s. > Uh... it has an 'S' on it that looks like two 'C's > hooked together, one upsidedown. Is that Signetics? Sounds like it... here you go: Intel, Motorola, Signetics, Hitachi etc 2532/2732: A7 1 24 Vcc A6 2 23 A8 A5 3 22 A9 A4 4 21 A11 A3 5 20 ~OE/Vpp A2 6 19 A10 A1 7 18 ~CE A0 8 17 D7 D0 9 16 D6 D1 10 15 D5 D0 11 14 D4 GND 12 13 D3 Texas TMS2532, Hitachi HN462532 (JEDEC): A7 1 24 Vcc A6 2 23 A8 A5 3 22 A9 A4 4 21 Vpp A3 5 20 ~CE/~PGM A2 6 19 A10 A1 7 18 A11 A0 8 17 D7 D0 9 16 D6 D1 10 15 D5 D0 11 14 D4 GND 12 13 D3 -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 9 months

2532 EPROM pin-out

by pete＠dunnington.u-net.com

OOPS I just realised I listed the Motorola 2532 as the same pinout as the Intel 2732; it's actually the same as the Texas 2532. Sorry! -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 9 months

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

by pete＠dunnington.u-net.com

On Mar 22, 19:47, Eric Smith wrote: > Pete Turnbull <pete(a)dunnington.u-net.com> wrote: > > I'm not sure these are repeaters, though. So a signal that's sent from a > > station on one of the AUI interfaces would go onto the wire, but I'm not > > sure that it would get back (directly) to the other AUI interface(s). > > It had better, or you don't have a functional ethernet, because two of > the nodes can't talk to each other. Also, the nodes have to be in the > same collision domain, so there's not really anything to be saved by > using some wacky scheme where the nodes can't talk to each other. I have seen such schemes. The small objects sold as "passive" 2-port or 3-port 10baseT hubs work like that, and two adjacent nodes can't talk directly to each other. It rarely matters. Well, I guess that depends on your network setup, actually! If you've not seen them, they look like a little black (usually) box with two RJ45 sockets on one end (into which you connect, say, two workstations or PCs) and a short RJ45 cable at the other end (which you connect to a real hub, switch, or a server). They're intended to let you connect more clients than you have hub ports. It's not a question of using some wacky scheme; rather a question of simplicity: if you want the adjacent nodes to talk to each other, you need to have the Tx from each connected to the Rx of the other. That's easy to arrange with just two 10baseT ports (that's all a crossed cable does, after all), but with three (as in the so-called passive hubs) you would end up with *everything* connected together -- or you need some electronics to isolate and filter (as in a proper hub/repeater). The passive units don't have that, so the two RJ45 sockets can each talk/listen to the RJ45 cable, but not to each other. There's a similar problem connecting three or more AUI ports; it's further complicated by the collision detect, which is normally done in the transceiver. Now if it were a multiport repeater, I'd have expected all the AUI connectors to be the same gender (since they'd be functionally equivalent). But the fanout units have one of a different gender, so I suspect that either they use a similar scheme to the passive hub I described, or they actually have more electronics than a normal repeater (or at least arranged rather differently), in order to get the signals in the right arrangement to drive a transceiver instead of a drop cable to another AUI. -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 9 months

2532 EPROM pin-out

by bill＠chipware.com

Could some kind soul post the pin-out of a 2532 4Kx8 EPROM? Thanks, Bill

24 years, 9 months

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

by pete＠dunnington.u-net.com

On Mar 22, 14:52, Philip.Belben(a)powertech.co.uk wrote: > 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! Yes, I know :-) Mine has the edge connector, not the expansion block. > 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. Seems like the hard way to do it... > 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. I was actually thinking of replacing the 74154 with a socket, to get access to all the signals I'd want -- I could enable (or not) all the RAM that way, and use the internal ROMs. It would only require one 22V10; and I would prefer to use several ROMs (probably 27256s) for the alternate BASICs. I'd take the data lines from the edge connector, probably. If you look at the PET circuit, you'll see the data lines to the edge connector are buffered, and the control to that buffer is hardwired (via AND gates and an inverter) to several of the SEL block selects from the 74154; similarly, the RAM buffers are hardwired to SEL0 and (via an OR, a NAND, and a link) SEL1. So you can't put replacement RAM on the expansion connector without doing something about that 74154... Plus, the SEL lines relevant to the ROMs aren't present on the edge connector, but they are on the 74154. -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 9 months

AXP vs VAX (was Re: Aaaaahhhh... 'Tis Good to be Back!!!)

by ethan_dicks＠yahoo.com

--- healyzh(a)aracnet.com wrote: > > Ow... that's scary. I am in the process of _finally_ building up this > > AXP133 "no-name" board... > Since you're running Sparc's with 64MB, to give you an idea of what I > consider acceptable performance, I don't consider Solaris 2.6 acceptable in > 64MB, but it's quite nice in 96MB on my Sparc 2. I don't consider 64Mb acceptable if I'm running CDE. It's horrible. Things are sluggish but not painful under OpenWindows. I'd run 96Mb if I could, but I don't have the Sbus expansion card. I used to use a Sparc 5/110 as my primary desktop machine at Lucent, and with 256Mb of memory the only ongoing problem I had was with starting up Netscrape - it took much more than a minute. Once I was in, things were ducky. I could even run ViCE at 200% 6502-emulation speed with no problems. > In the case of OpenBSD I was able to get a Tulip-based 10/100 NIC working > with no problem in the AS200. I *can not* get one working under OpenVMS, it > looks like I need a real DE500 to work under OpenVMS. I bought a real DE500 once, just for this box (not that it runs OpenVMS due to other driver issues). It never left the show with me; I think I set down the bag and walked off. Not the first time, but usually I remember while I'm still in the same aisle. > On the RAM, I *always* check for used True Parity 72-pin SIMMS when I'm > anywhere that has used RAM. Me too. I'm up to five pair of 16Mb and one pair of 4Mb. :-( > You're lucky. The AS500 requires custom RAM, the only way I'm going to get > it more memory is by spending about $500 :^( Ow! Speaking of custom RAM, I notice that on diagnostics, the IPX detects 33bit vs 36bit parity SIMMs. Are there any performance differences? I only have three or four 33bit 16Mb SIMMs. I was just wondering if there were any benefit to take these to 36bit. I plan to use the IPX as our primary DNS server at work, so enhanced reliability is a benefit. -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

24 years, 9 months

OSI bliss...

by dogas＠leading.net

Wow. Hi everyone. A hot tip, a long drive, lots of digging, and a pocket full of kryptonite turned up an OSI C3C12 yesterday! It's a 4 component system including the CD2 8" floppys, a big CD23 Shugart SA4000 harddrive, and a Hazeltine terminal that's OSI branded (neat.) It sports a 17 slot backplane with a 525, 590, CSS cpu+ (that is cracked), and 3 522's now in it. I found another box of boards that had 2 510's (my favorite), a 555, 2 550's, 2 470's, and 3 520's, and a CA-18E ((on a 550 board)?) that hints at level III networking) Also got a bunch of software like os-65u v1.43 timeshare, ( w/mputil...) Looks like it can handle 3 users maybe. And there are boxes of disks I haven't even gone through yet. The documentation was a wonderful find too. Most of it is preliminary docs of things like the: Ohio Scientific Multiple User Computer System Manual C2-8p Users Manual C3 Setup and Operations Manual (with the C3 Utilities and Demo disks (!!!)) OS-DMS Shugart SA4000 servicing info OS-65u Ref Manual a *huge* binder of tech and sales newsletters and a real cool OSI Servicing Data book for *many* of the osi boards >from 470-594 and cii and cIII systems Then the ghost of classiccmp-past infused and led me back to a dark dusty workbench where I scored 3 boxes of molex connectors that I needed desperately. Oh, I found a Motorola EXORmacs system in the same pile too. yipee! My home is smaller. One happy ccmper signing off... ;) - Mike: dogas(a)leading.net

24 years, 9 months

AXP vs VAX (was Re: Aaaaahhhh... 'Tis Good to be Back!!!)

by ethan_dicks＠yahoo.com

--- jmd <jmd(a)infinet.com> wrote: > Ethan > I have 1 DEC 205 NIC if you are interested. ISA slot. How much? -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

24 years, 9 months

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

by pete＠dunnington.u-net.com

On Mar 22, 0:51, Eric Smith wrote: > Chuck McManis asked: > > I'm confused, aren't these "fan out" units just hubs? > > Aaron Christopher Finney replied: > > These simply provide multiple ports on a single tap. I indicated my > > interest in them for the thick ethernet segment in my garage, as I only > > have 3 transceivers tapped into it at the moment. Physically, they just > > connect to the tapped transciever. > > Which, as Chuck suggests, is a effectively a description of a hub, albeit one > that has AUI interfaces rather than 10-base-T. Ethernet hubs are technically > multiport repeaters, and are subject to all of the topology and distance > limits of repeaters. I'm not sure these are repeaters, though. So a signal that's sent from a station on one of the AUI interfaces would go onto the wire, but I'm not sure that it would get back (directly) to the other AUI interface(s). Anyone know? -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 9 months

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test-drb March 2000