My small collection

[fxg]

I know the 486 SX25 is no big deal and I don't usually collect machines this new, but I have a "thing" for DEC machines of any kind :D Actually I replaced the CPU with a DX2-50, which is the furthest it can go. All I want is to get it working, no performance interests me.

Concerning the 386 DX40... Well, I've got one [unfortunately soldered to it's mainboard, but it's a pretty good mainboard] WITH a Cyrix 387DX 40MHz FPU It's a great piece to have, and play with. I've got 16MB on that mainboard and a , but i'm currently looking for a nice case for it.

 

[IBMMuseum]

A 486/25MHz is not a big deal. It easily could be overclocked without cooler or passive heat dissipator, to just 33MHz. In fact 486/25MHz are 486/33MHz or recto-verso. Intel used to relabel these processors from 486/25MHz to 486/33MHz to update its selling politics.

Generally I am in in agreement with at least the first part of this statement. In my experience single-speed (same clock rate internally & externally) Intel CPUs & NPUs will tolerate going to the next higher speed (16MHz to 20Mhz, 20MHz to 25MHz, 25MHz to 33MHz, 33MHz to 40MHz; what amounts to 25 to 33% faster). Never had to do it much with CPUs (because I usually had a higher speed around) & typically I would also put a heatsink on by default (but the normal operating temperature of a 486 CPU is 135 degrees Fahrenheit).

...Note that most 386/33MHz or even 386/25MHz are faster than a 486/25MHz. Not to mention the almighty 386DX/40MHz, the king of all 386 processors. That was faster than most 486/33MHz. If I'd ever get my sticky hands on one of these... ever...

And in disagreement here. A 486 is supposed to be roughly double the processing power of a 386DX at the same clock speeds (just the fact of having at least an 8Kb L1 cache internally alone tips the scales). I can back this up with benchmark results.

However a 386SX will typically place a fraction lower than a 286 at the same clock speed. Putting L1 cache on the CPU can give quite a boost in performance, something Intel didn't do until the 486 level. The AMD 386DX-40were pretty good, but there is some equal competitors put in the same 386DX form-factor chassis.

 

[MAV]

I tend to say you're right. As far as I know, there was first the 486SX-20MHz that Intel introduced for marketing reasons in times Am386DX/40MHz was already on the market. The idea of having a processor which was names a 486 (I do not speak here about Cyrix 486SLC-33MHz ... I believe this is actually a 386) was overwhelming but people didn't bought large quantities of this processor.

Then I remember was the 486-20MHz (without SX) had the 8Kb of cahce and essentially was a revised version of a fast 386DX but including ca co-processor (FPU). I never remember seeing one of these in the flesh.

386DX-33MHz was as far as I remember a very appreciated processor of the time.

But about the 486SX-25 I've got nothing but bad words. It's in essence a 486DX with the co-processor disabled. Why Intel chose to build the co-processor and hardware-disable it in the chip, I don't know.

Indeed, for stability at least heatsink / passive cooling is required for a 486SX-25 to run at 33MHz. You are perfectly right but if not put to hard work, it'll do without a heatsing although life span shortens.

This classement is done through my experience that might just not be that great si I expect some critics! I could learn some things now, as I missed the right time.

PS: Indeed I've heard (but never seen) about a Harris 286-25MHz processor outperforming a 386SX-25MHz.

The sum of all respects,
MAV

 

[IBMMuseum]

I tend to say you're right. As far as I know, there was first the 486SX-20MHz that Intel introduced for marketing reasons in times Am386DX/40MHz was already on the market. The idea of having a processor which was names a 486 (I do not speak here about Cyrix 486SLC-33MHz ... I believe this is actually a 386) was overwhelming but people didn't bought large quantities of this processor.

Ok, let's talk about the Cyrix (and a few others) CPUs. There are a few confusing part numbers, but "SLC" means that the CPU would have been a replacement for a 386SX. There were later versions that doubled the clock speed internally (for both 386SX & 386DX replacements), and had 1Kb L1 cache or more (activated by software). This is right before the time Cyrix started working with Texas Instruments & IBM (mainly for legal challenges from Intel, which TI & IBM had cross-licensing agreements with).

IBM was allowed to modify the Intel 386SX code mask & produced a few CPUs that were able to be put in the limited 24-bit memory addressing (16Mb RAM maximum) and 16-bit data platforms for a little more processing power. The IBM 386SLC was a single-speed CPU, but added 8Kb L1 cache (and interestingly ran all 486SX instructions too). Later 486SLC2 & 486SLC3 doubled and tripled the clock rate internally, and add a 16Kb L1 cache.

Recently I benchmarked an Intel 386SX-20, & IBM 386SLC-20, 486SLC2-40, and 486SLC3-60 in an identical environment (actually the same system, because the upgrades are in the form of being a daughtercard) with Landmark 2.0 (a common DOS version out there). Some platforms even have the 486SLC2 at 50MHz & the 486SLC3 at 75 or even 100MHz! Here are the scores (results are given in the MHz speed needed for a theoretical 286 CPU to equal the processing power):

386SX-20: 20.68
386SLC-20: 45.92
486SLC2-40: 91.68
486SLC3-60: 136.87

Then I remember was the 486-20MHz (without SX) had the 8Kb of cahce and essentially was a revised version of a fast 386DX but including ca co-processor (FPU). I never remember seeing one of these in the flesh.

All Intel 486 CPUs started at 8Kb of Write-Through cache, with it increasing to 16Kb for the DX4 line. A few CPUs at the end of the DX2 & DX4 series had the ability to set the L1 cache to Write-Back mode. Look over www.gilanet.com/David/Intel486.htm for more information.

386DX-33MHz was as far as I remember a very appreciated processor of the time.

Which is amazing for the amount of bugs the Intel version had. Intel didn't kill all of them until the F-step, which was some years later after production started. By then the 386DX market was pretty dead anyway & I've never seen an F-Step (visibly diffent label is the only way to tell).

But about the 486SX-25 I've got nothing but bad words. It's in essence a 486DX with the co-processor disabled. Why Intel chose to build the co-processor and hardware-disable it in the chip, I don't know.

Only the early 486SX were made this way (and allegedly at the start when the FPU section failed). The 486DX were made first, the 486SX was a later "budget" CPU (just like the 386DX & 386SX). 486 CPUs would have to be tested before the packaging was complete, because their CPUID tells which model they are.

Indeed, for stability at least heatsink / passive cooling is required for a 486SX-25 to run at 33MHz. You are perfectly right but if not put to hard work, it'll do without a heatsing although life span shortens...

I do it just to avoid cooking things...

This classement is done through my experience that might just not be that great si I expect some critics! I could learn some things now, as I missed the right time...

But came to the right forum!...

PS: Indeed I've heard (but never seen) about a Harris 286-25MHz processor outperforming a 386SX-25MHz...

Just look at the MHz value the 286 has to be at to place equal to my 386SX score above...

 

[Terry Yager]

Just look at the MHz value the 286 has to be at to place equal to my 386SX score above...

So the 386SX-20 is just about equal to a 20MHz 286? Then the above-mentioned 25MHz 286 should out-perform a 386SX-20...

--T

 

[dongfeng]

But about the 486SX-25 I've got nothing but bad words. It's in essence a 486DX with the co-processor disabled. Why Intel chose to build the co-processor and hardware-disable it in the chip, I don't know.

You are right, SX chips have the co-processor there but it is disabled. Apparently they were processors that failed the FPU tests, so therefore adding the extra work to disable the faulty FPU actually made them more expensive to produce!

 

[IBMMuseum]

So the 386SX-20 is just about equal to a 20MHz 286? Then the above-mentioned 25MHz 286 should out-perform a 386SX-20...

Yes, but wouldn't have the 386 improvements to run EMM386 or Windows 3.x in Enhanced mode (as long as you have at least 2Mb of RAM). Look how the addition of 8Kb L1 cache (and probably a few other optimizations) more than doubles performance for the IBM 386SLC-20. And that doubles again for the 486SLC2-40 (as it should, since the clock is doubled internally). Then the 486SLC3-60 is the processing power equal to the 386SLC-20 & 486SLC2-40 put together. I can hardly wait to test the performance of a 486SLC2-50 & 486SLC3-75.

 

[MAV]

First of all,

Hello to all of you out there!

IBMMuseum, indeed a good source of information you are! I know Landmark Speed and have quite used it in the past with my ageing PC's. The "processor-talk" was indeed very, very constructive. I guess newer users could learn things from that discussion.

About the comparison of a 286-20MHz and 386SX-20MHz, yes, it is true what IBMMuseum said. In principle, any 486 or up is a revised 386 wich is a revised 286. Newer instruction sets were added with newer processors but the x86 "core" is the same. I believe a P4 could still run pieces of assembly code written for an i8086 processor.

And referring to the 286, I'd love to see a Harris 80286-25MHz. I heard they fly.

i386DX-33MHz was indeed less popular than Am386DX-40MHz. I remember I saw once (in a bazaar) a large mainboard fitted with an i386DX-33MHz so there were some attempts to do things the hard way (TTL-Logic or CMOS-Logic) but I never saw a small compact mainboard fitted with an i386DX-33MHz. Like the old times, all is done through the hard way. For example I've got an UNiSYS 286-10MHz. The mainboard is huge full of TTL-Logic parts.

About the 486's with the co-processor disabled, maybe the production costs were approximately the same but the price in stores for the SX version - less than for the DX unit. I have an i486SX-33MHz. It's resting in the magic processors box, near the Am286-10MHz and the others -- haha.

I had once a big COMPAQ laptop computer based on an i386-20MHz. It was labeled SLT. Any ideea what that meant?

The sum of all respects,
MAV

 

[Terry Yager]

I dunno bout the 25MHz, I've only ever seen one of 'em. I did, however, rescue a Harris 20MHz based XT-sized board with 2Mb RAM installed (1Mb x 1, 20-pin DIPs) yesterday. (Sorry guys, I'm keeping it for myself). I'll let y'all know the Landmark performance rating after I get it built up.

--T

 

[fxg]

I only have a 20MHz Harris 286, but unfortunately it's on a VLBus BusLogic SCSI controller, with 4 MB of RAM

 

[MAV]

I've got a Zilog Z80 processor bolted on an Adaptec SCSI Drive. Yours is what I'd want to see. Could you take a picture?

The sum of all respects,
MAV

 

[fxg]

I took a picture and you cand find it here: Link

I found something for my collection also:

I.C.E. Felix HC-90 computer [Romanian Sinclair 48k clone] - they're somewhat common around here, but I've lost mine a few years ago during a move so I was glad to find this one. It came with the AC adapter, a bunch of tapes, Kempston controller adapter, Kempston joystick [which is acutally a Sintez - old Russian brand] and all the cables. I have to fix the AC adapter connector, but other than that, it works.

 

[Terry Yager]

Nice! Two things tho:

a) It's IDE, not SCSI

2) Very interesting RAM, I've never seen the like before. Are they actually flipable, SIMM on one side & SIPP on t'other?

Either way, I'd hang onto it if I were you, it's very unusual. (I think I'm starting another 'weird card' collection myself).

--T

 

[fxg]

@Terry - you're right... I know it's an IDE / FDD controller, but I don't know why I keep remembering that it's a SCSI controller. Weird...

One more thing: the memory is just normal 30 pin SIMM modules [I tried the controller with 4 x 4MB and it works very well].

 

[Terry Yager]

Aah, I see you already have a weird card collection. Would you like to add a few more to it? Shipping prolly won't cost much. I'll try and make a list later.

Anyways, can you confirm if the RAM modules are reversable or not? I think can see pins sticking out the top side of them, or is that a trick of the lighting or some such?

--T

 

[fxg]

I actually enjoy collecting various cards so, if the shipment isn't too much [considering the fact that Romanians don't make nearly as much as US ppl], I'd love to take them off your hands

If you can, please give me a shipping quote to 031294 Bucharest, Romania.

Memory is not reversible, it's just plain SIMM modules.

 

[Terry Yager]

Memory is not reversible, it's just plain SIMM modules.

Are you familliar with SIPP (Single In-line Pin Package) modules? They're basically SIMMs with pins soldered onto the edge contacts. I don't have any to show you, but I took a picture of a couple of motherboards that have SIPP sockets.

--T

 

[fxg]

Yes, I'm familiar with SIPPs [I had a Compaq Deskpro 386DX/25 that used those modules], but this is not the case. What you see in the picture is just a lighting trick, because they had to use those flat connectors and the contacts stick out just enough to shine

 

[Terry Yager]

I've gathered up all the weird cards, but there's more than I thought. Perhaps I could contribute something towards the shipping, on condition that you photograph them and make the images available on your site for all to enjoy.

The list:

1. For starters, there's the PAS-16 soundcard you already expressed interest in.
2. CMC International C Voice (Voicemail board).
3. Paradise PEGA I (Autoswitching EGA/CGA/MDA).
4. Paradise PEGA II (This is a very weird board that uses ZIPP memory, and there's a lot of 'em, 48 in assorted sizes).
5. Computone Advantage (This is an unusual 8-port serial board, with RJ-11 jacks. It has an 8088 CPU, and uses 3 x Z80B SIO chips).
6. A genuine Hercules card.
7. A CT-6040 (A genuine Hercules clone).
8. A Texas Instruments CRTC board (Proprietary color video).
9. A Persyst BoB (This was a very advanced color graphics board in the CGA era).
10. Metheus video card, dated 1990 (I don't know much about this one, but it's really weird-looking, with attached daughterboard).
11. A very weird Hewlett-Packard video board with a secondary board attached via cable and having separate RCA jacks for R, G, & B.
12. Control Systems Artist video board (A very weird single-slot, dual board setup, with lots of memory on the daughterboard, 60 x 64K).
13. AST FASTboard / 386 (Appears to be an SBC of some sort).

I'll get 'em boxed up and weighed, and we'll see what the damages are.

--T

 

[fxg]

I'm planning on adding a gallery on my site with all the stuff I've got, but time is needed, and that's the main issue. Also upload bandwidth is a problem. The server is at home, and I only have 256kbit upload... I'm hoping to get some high-speed hosting.

Those cards are making my mouth water :D I don't think I could find such cards around here... Actually, I've never heard of Persyst BoB till now

I'd really appreciate your massive input to my growing collection :D

Seeing as you have such extensive knowledge in older hardware, maybe you can help me identify a video card. Picture. It has Texas Instruments chips all around, Cirrus Logic GD-5401 [which as I remember is a fairly weak graphics controller] and a chip covered by a heatsink [which I'm afraid to remove as it might damage the chip - it's happened before :D]. The weirdest part is a connector near the DIP switches, which looks like a 68pin SCSI connector. The thing is that the system won't boot with the card because the previous owner messed with the switches. Now all I want is to find out what it is so I may find the correct settings for the DIP switches and make it work


The link in my signature takes you to all the pictures of my collection and will be updated accordingly. I just added a couple of pictures of my "new" AdLib Gold 1000, a Pine Tech VGA card with an IGS chip [i've never heard of them before], and an ATi combo card, 16bit VGA adapter + Bus Mouse controller...