Just a guy with a love for tech

AST Advantage! 624

Adam L January 01, 1995


ItemMy original machineThe stock specThe upgrades
NameAST Advantage! 621eAST Advantage! 624
CaseDesktop ATX
MotherboardBCM FM561
ChipsetSIS 5511/5512/5513
ProcessorIntel Pentium P54CIntel Pentium P54CIntel Pentium P54C, SY062
Speed75 MHz100 MHz120 MHz (CLK @ 133 MHz = 66MHz x 2)
Primary Storage1.2GB WD CaviarNone9 GB Quantum Atlas V
L2 Cache"None15ns 256KB Pipeline Burst COAST
CD-ROM Drive"Torisan CDR-S1GBTC SLL16 (16x IDE)
Modem"Pace Message Desk 34 28.8K"
Audio"ESS1788 AudioDriveOn-board + WaveBlaster X2GS
Network"NoneD-Link DE220 ISA

Videos of boot and usage available:


The first PC I personally owned, though my original machine was the lower-spec 612e version, was generously given to me by a neighbor since they had just recently upgraded to a Time Computers branded machine running on an AMD Duron 600Mhz and Windows ME, but I was super grateful regardless as I had no computer of my own at the time, there was the "family" computer but access was closely guarded by my father and my time was limited because it was connected to the internet using dial-up.

I acquired this similar machine from eBay recently and fully upgraded it to its maximum specification, something that I would never have been able to afford to do in the early 2000s.

This is the first computer where I was properly able to sink my teeth into RTS games such as Warcraft and Command And Conquer (TODO: Link to the game, not the index)

CPU Upgrade

I was pleasantly surprised that I was able to drop in the SY062 P120 and have the machine accept it, normally the CPU would run with a Front Side Bus of 60MHz but since the P100 ran with it at 66MHz, the P120 is running slightly faster at 133 due to its 2X Multiplier (2x66=132) instead.

I need to sit down and document the jumpers for this motherboard at some point or find a hard copy of the manual.

AST computers are renowned for being sticklers when it comes to compatible hardware even though it's a Socket 5 board, it was very strict on the CPUID and extremely fussy about PCI timing from what I can remember. I had major problems in the past getting it to POST with various add-in sound cards, IDE controllers and port expanders.

In the original machine I had, I tried to upgrade from the P75 to a P90 and it refused to start with one of the CPUs in particular but a slightly earlier revision POSTed just fine even though they had the same Voltage/FSB.

CD-ROM Drive

(EDIT: Slightly outdated, See updates below for more info)

I've had to replace the original CD ROM drive (Torisan CDR-S1G) as it was having trouble reading disks with a COMPAQ CRD-8402B.

I tried re-calibrating the laser using the potentiometers on the board but it was having none of it, I suspected a failing laser diode. I couldn't even get a stable audio signal from a music disk with constant jumping and resets.

I searched high and low for a suitable replacement but every drive from that area is now either dead or ridiculously overpriced. I found a Mitsumi CRMC-FX810S 8x drive in Germany but it was EUR 70 for the drive and another EUR 50 for shipping!

Every other drive I found was either too fast (48+) or was a CD-RW or DVD Combo, neither of which was to be released until some time after 1996. I know that 40x is still way faster than what was available but in terms of cost and the fact that the IDE controller doesn't support that kind of transfer speed anyway, it seemed like a fair trade-off.

Update 2022-09-07

I was able to get my hands on an LG CRD-8322B which is a 32x speed IDE CD-ROM Drive with a date code of the 25th week of 1999 (9925) which is much closer than the COMPAQ, so I'll be putting this in the machine instead.

Update 2022-12-18

Even better, I now have a Mitsumi CRMC-FX400B whose date code is Feb 1996 and is a Quad Speed, just like the original. It's also the same drive as what some other AST machines used to ship with. A great find to complete the restoration.

Update 2023-01-23

Swapped the Quantum HDD for a Seagate, because the BIOS uses 12 bits to represent the drive geometry, the BIOS is not able to boot from or properly use drives larger than 2.1GB. This is why I originally added the Promise Ultra 100 controller to work around that. However I was able to procure a ST32122AB 2.1GB drive and use that to boot from. I re-installed Windows 95 OSR2 and then re-added the Quantum drive as a secondary disk. Since Windows uses its own 32-bit drivers, it is able to correctly detect and use the 6GB Quantum without issues. However, in pure DOS mode, this drive won't work properly but if I want to use pure DOS, I'll just need to make sure it's on the primary drive.

With the removal of the Promise disk controller, that freed a PCI slot, which I then used to add a RTL8139D Fast Ethernet controller for LAN access. This makes it much easier to get files onto the machine via my FTP server.

Adding the X2GS was as simple as pushing the PCB onto the Wave Table header, heading into Windows and setting the MIDI device to the ESS MIDI port instead of the ESS FM Synthesiser and it just worked.

Whilst I had the cover off, I took this opportunity to swap the aging and very loud Sunon KDE1208PTS3-6 case fan with a Noctua NF-R8 redux-1800 for equivalent cooling but at half the noise.

I also added a Gelid Solutions Silent 50mm fan to the CPU heatsink to keep the temperatures down which dropped from 62C to a much nicer 30-35C.

My next major concern is the PSU, whilst it's not currently giving me issues, I do acknowledge that the PSU is 23 years so I may want to think about replacing that next.

Update 2023-11-12


Over the past few weeks I tested the system with a SIS 6326 3D accelerator, a potential upgrade some may have considered pairing with a machine like this. Whilst the card did in fact work, I had no end of compatibility issues with it, especially 2D games like C&C 95 which only showed FMVs in black and white, However the gameplay itself seemed fine but I just can't play C&C without FMVs which carry almost the entirety of the storyline.

So I once again replaced the VGA card with a 2MB ViRGE/GX clocked at 75MHz from 1996, just a year after this machine debuted,

Though many people claim it was a terrible 3D card (mostly because they tested it with much later titles and benchmarks), I will admit, it certainly wasn't the fastest 3D accelerator of its time, it was well within the budge of most people and it did well in some titles, if you're one of the lucky people to find the DX/GX cards that were clocked at 75Mhz or higher, games like Moto Racer ran pretty well at modest resolutions.

My reason for installing this card is not for its 3D prowess, but for its 2D compatibility. ViRGE cards are renowned for fast GDI and 2D operations, combined with their good history of DOS support.

So far C&C, Warcraft 2, Transport Tycoon, Rollercoaster Tycoon and Dungeon Keeper all played well on it which is suprising considering some of those were 1997 and later.

Hard Disks

I've removed the Promise IDE controller card and installed an Adaptec AHA-2940UH2 Ultra2 (aka Fast-40) SCSI controller in its place, To that end it, the Seagate Medalist and Quantum Fireball were removed and replaced with a 9 GB Quantum Atlas V drive.

Since Ultra2 first initially appeared in 1997, it would've been right on the edge of what could be considered era appropriate, In my eyes, a machine of this cost would not simply have been thrown away and many people would've been holding on to them for as long as possible.

I found a magazine advert showing a machine of this specification would've been worth as much as £13,500 in that year.

I should also mention that there's a rather annoying bug in the BIOS, if you add a SCSI card you'll no longer be able to boot from the onboard IDE, it's one or the other. This was the reason why I removed both the IDE drives, originally I planned to keep the Medalist and boot that as my primary drive and use the SCSI drive as my game storage, but since I can't boot from IDE anymore I opted to remove the IDE completely to save headaches.


The Mitsumi CRMC-FX400B, whilst it was the correct choice, had a cracked facia which detracted from the overall appearance of the machine, so until I can get another working drive, it has been substituted with a BTC (Behavior Tech Computer) 16X SLL16 drive which looks and works great.


The RTL8139D was replaced with a period correct D-Link DE220 ISA, this was also a required change since the PC only had 2 PCI slots.

With one of them being used for either SCSI/IDE and the other being used for VGA, I needed to switch from a PCI card to an ISA one.

While this does reduce the speed considerably from 100Mbit to 10Mbit, this machine is barely able to saturate it anyway so having a higher link speed was totally negated by the CPU.


Drivers and Manuals


BIOS files are incremental and not differential, you must install each one in sequence.

Requires a floppy disk drive or emulator.


Back to top