Apricot Xen 486 PC fixed and upgraded

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Apricot Xen 486 PC fixed and upgraded

Postby Darkman » 2016-8-02 @ 09:31

So very recently I got myself a 486 based Apricot Xen PC , However it was not in a fully working condition , as the hard drive was faulty , and the RAM seems to be faulty too (its 16mb but reports as 12mb), it was also missing a Sound card, or any cache and wasn't the cleanest thing , inside or out. So I set about making this into a more competent system , and this is still a work in progress.

the Original Quatum drive (which was detected in the BIOS as a 160mb drive but failed to boot or let me install DOS) was replaced with a 7200rpm Western Digital 20GB drive which Im running with some driver overlay software , as the BIOS only detects 504mb like many at the time.

For sound, Im going with dual sound cards, one is a Sound Blaster 16 (CT1740) and the other is an Ensoniq Soundscape , that way I can have proper FM synth as well as decent MIDI.

Ive already ordered the necessary cache chips (9 of them , 20ns is what is described in the manual , so Im going with that) for 256k which is the maximum this motherboard will take, I just have to wait for them to arrive

the old RAM was swapped for a working 16mb of RAM and the system uses 72 pin FPM RAM , actually finding RAM that worked properly was a bit difficult, since most of the RAM I have either would not boot ,or give me errors , but finally Ive found some RAM that actually works.

the CPU is a 486 DX2 66Mhz , actually to be accurate, its an Overdrive CPU , but as far as I know there is no difference , Im not quite sure whether this machine can take a faster CPU (if anyone knows, Id be happy to hear)

The onboard graphics chip is a Cirrus Logic GD5428 which was already upgraded to 1mb of VRAM , you can actually go to 2mb but it requires a different type of chip and Im not exactly sure what it is (the manual does show it, but Ive never seen that type of IC)

the system has a 16x BTC CD-ROM drive , I may or may not replace it , but it seems to work just fine , and getting something too fast would be pointless (I have a 48x Sony CD-RW drive, but its probably overkill)

There are several things to like about this system ,and a few not to like , for one it has PS/2 connections, meaning I can use my normal kbd/mouse combo without adapters , it also uses standard CR2032 batteries as opposed to the barrel batteries one finds on these (although the metal hinge keeping the battery in was broken , so I had to improvise). Also , while the system is quite compact , it does mean It only has 3 ISA slots , and no VLB or PCI , it also only has one IDE channel , so until I get an ISA IDE controller (anyone know a good one?)the HDD and CD are sharing the IDE cable (which had to be replaced too , as it was falling apart a bit)

the BIOS also needs updated, and I have found the file, but its in a .bin format , and Im not sure what program can be used to flash the BIOS, since the archived apricot website is somewhat broken.

Ill post some pics now, and maybe some more later (Ill benchmark it too , though keep in mind it still doesn't have any cache)

Image

not perfect, but given it was covered in dust I think I cleaned it ok , the CD drive is behind the Xen cover, of course.

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broken hard drive, shame as I quite like Quantum drives, but it wouldn't have had enough space anyways

Image

The expansion part of the system , the Video chip and RAM are under that SB16 (the Ensoniq will be installed later), sadly the IDE port on the SB16 is a Panasonic CD interface, so it wont work with that CD drive.
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Re: Apricot Xen 486 PC fixed and upgraded

Postby brassicGamer » 2016-8-02 @ 10:44

Nice little machine there. Love the placement of the activity LEDs on the case with the graphics around them and the concealed optical drive. Plus that CPU isn't one you see often, as it is a retail-only drop-in upgrade version of the OEM DX2. Are there any clues as to the original spec? If it was something like an SX-25 then it's likely it only had 4mb or 8mb to start with. Strange they didn't add cache when the CPU was upgraded.

It's quite possible that the built in graphics uses a local bus connection internally as a lot of manufacturers did this before VLB came in. Doesn't help with potential upgrades though but, given that I think the DX2 is as fast as you can go, that shouldn't be an issue. It would be interesting to see the Doom performance.

Any chance of a pic of the mobo? I'd like to see the graphics RAM and the BIOS chip. I'm guessing it's a custom Apricot job, but it will have come from one of the big BIOS makers originally and they have their own flash programs of course.
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Re: Apricot Xen 486 PC fixed and upgraded

Postby Darkman » 2016-8-02 @ 12:07

Ill post a better photo of the motherboard later during the day hopefully.

From what Ive checked on the Apricot site, if you bought the DX2 model , it already came with 256k cache chips installed, however, given that there aren't any, and given that its using an overdrive CPU (not something Apricot would have used) , it probably is the case that this was an SX class machine , although interestingly the jumper switches are set to 256k cache, so Im not too sure.
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Re: Apricot Xen 486 PC fixed and upgraded

Postby Darkman » 2016-8-03 @ 09:24

Due to my PC dying on me (I think the power supply is dying) it took an extra day for me to post this, the photo isn't very good , but it will do for now

Image

running Speedsys got me a CPU result of 23.59 , while the Doom benchmark (timedemo 3) gave me a result of 23fps, I assume it will get a bit of a boost when the cache is installed
The motherboard is actually an Acer A1 motherboard, from what I can see.
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Re: Apricot Xen 486 PC fixed and upgraded

Postby clueless1 » 2016-8-03 @ 11:07

Darkman wrote:running Speedsys got me a CPU result of 23.59 , while the Doom benchmark (timedemo 3) gave me a result of 23fps, I assume it will get a bit of a boost when the cache is installed
The motherboard is actually an Acer A1 motherboard, from what I can see.

Those numbers are right in line with where they should be. If it's any help my dx2-66 scores 25.15 in Speedsys. But the interesting part is, depending on how fast the memory timings are set, disabling L2 can make almost no difference:
Fastest BIOS timings and L2 disabled: 25.14
default cache timings, "fastest" DRAM speed, L2 disabled: 24.12
default timings all around, L2 disabled: 22.72
"slowest" DRAM speed,L2 disabled: 22.66

So with fastest DRAM and cache BIOS timings, disabling L2 makes almost no difference (25.15 vs 25.14) in Speedsys. With slowest DRAM and caching timings, disabling L2 drops Speedsys by 10%.
The more I learn, the more I realize how much I don't know.
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks
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Re: Apricot Xen 486 PC fixed and upgraded

Postby chinny22 » 2016-8-03 @ 20:25

I wouldn't worry about the single IDE channel, with a large enough HDD you don't really need it for games and if you add a network card in that last ISA slot you wont even need it to install software.
If its a acer board maybe they will have something to apply the .bin firmware update?
Look forward to seeing go from start to finish
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Re: Apricot Xen 486 PC fixed and upgraded

Postby Darkman » 2016-8-03 @ 21:44

chinny22 wrote:I wouldn't worry about the single IDE channel, with a large enough HDD you don't really need it for games and if you add a network card in that last ISA slot you wont even need it to install software.
If its a acer board maybe they will have something to apply the .bin firmware update?
Look forward to seeing go from start to finish



thinking about it, I think it may well be an EPROM type BIOS , which means it will need more specialised equipment I dont have, and if it works, Im not messing with it.

right now, the hard drive is formatted with two 2GB partitions, 1 for the OS (using DOS 6.22 and Win3.11 , as one would expect, would be nice to try OS\2 one day, but sadly I dont have a copy of that (the DOS/Win3.11 disks Ive got are OEM Dell ones) and with some of the overlay software it seems to work , though even then it only seems to recognise 8GB of the drive.
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Re: Apricot Xen 486 PC fixed and upgraded

Postby Darkman » 2016-8-06 @ 15:39

a bit of an update, sadly the board in the Xen PC died, and Im not quite sure what it was (tried quite a few things, just blew I guess). Not wanting to be beaten by a pile of metal and plastic, I figured I may as well get a replacement board as long as it wasn't expensive.

turns out this wasn't such a bad turn of events as the board I found was from a Xen PC , but for a later revision, as the series was quite varied (you had 486SX , DX2 , DX4 and even Pentium 75 ) , all had the same cases and expansion capability (though the Pentium also had PCI slots), seems like the board I originally had was an earlier revision (probably meant for a 486SX). The new board has a number of improvements.

Image

The board has more CPU support via socket 3 (goes all the way to the Pentium Overdrive , though it may get upgraded to a DX4 at some point , depending on whether the games I want to run on it will benefit from this) , it has more RAM slots and dual IDE channels, and the graphics chip is now a CL-GD543x/VL, which is apparently just a somewhat upgraded version of the older board (still only 1mb of RAM , can be upgraded to 2mb via those RAM slots next to the Parallel port , anyone know what these are?). it also comes with 256k of 15ns cache, which seems to have been a standard on these boards. the white slot is apparently for what apricot calls their "proprietary multimedia board) which I dont have, but the older riser card works fine here. only issue is that the battery is a CR2335 type, which is harder to find.

as far as benchmarks (its still using the DX2 Overdrive), 3Dbench gets a score of 40.4 , PCPBENCH gets a score of 10.3 , Speedsys' CPU score is at 23.90 and Doom gets 29.3.

Here is the inside of the system so far (yes Im using rounded IDE cables, the case is quite compact obviously), ive taken out the dead battery until I find a replacement, at least its not a leaky barrel battery.

Image
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Re: Apricot Xen 486 PC fixed and upgraded

Postby brassicGamer » 2016-8-06 @ 21:43

Darkman wrote:the graphics chip is now a CL-GD543x/VL, which is apparently just a somewhat upgraded version of the older board (still only 1mb of RAM , can be upgraded to 2mb via those RAM slots next to the Parallel port , anyone know what these are?)


Looks like a variation on the theme of SIPPs
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Re: Apricot Xen 486 PC fixed and upgraded

Postby Caluser2000 » 2016-8-07 @ 01:36

brassicGamer wrote:
Darkman wrote:the graphics chip is now a CL-GD543x/VL, which is apparently just a somewhat upgraded version of the older board (still only 1mb of RAM , can be upgraded to 2mb via those RAM slots next to the Parallel port , anyone know what these are?)


Looks like a variation on the theme of SIPPs
They look a bit more like they are zip ram sockets. https://en.wikipedia.org/wiki/Zig-zag_in-line_package They're longer though then the one used on my Acorn A4000
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Re: Apricot Xen 486 PC fixed and upgraded

Postby Darkman » 2016-8-07 @ 07:57

its rather hard to tell , and Apricot didn't make it easy as their site doesn't give any tech details, it just refers to it by a part number. The best I can find is the manual

http://insight.actapricot.org/insight/k ... 349331.pdf

it does have a picture of the necessary chips on page 7/10
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Re: Apricot Xen 486 PC fixed and upgraded

Postby kazeobi » 2017-11-27 @ 18:45

Darkman, could you share some pics of isa riser from this system? I have the same socket 7 motherboard and psu/case, but no riser card. Thanks.
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