AST Advantage! 624

Posted 1995-01-01 ‐ 8 min read


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 CaviarNoneSeagate Medalist ST32122AB 2.1GB
Secondary StorageNoneQuantum Fireball CR 6.4GB
L2 Cache"None15ns 256KB Pipeline Burst COAST
CD-ROM Drive"Mitsumi Quad Speed IDEMitsumi CRMC-FX400B
Modem"Pace Message Desk 34 28.8K"
Audio"ESS1788 AudioDriveOn-board + WaveBlaster X2GS
Network"NoneRealtek RTL8139D Fast Ethernet

Pictures to follow shortly


The first PC I 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.

A distant relative?

Recently I stumbled upon the existence of an ASUS P/I-P55SP3AV motherboard which shares incredibly similar specifications with the unknown BCM FM561 board that the AST has.

They both share:

  • SIS 511X Chipset (5511/5512/5513)
  • An onboard SIS 6205 VGA Chipset
  • An onboard ESS1788 AudioDrive sound chipset
  • Similar ISA/PCI Slot counts (3/2 for the AST and 4/3 for the ASUS)
  • A very similar BIOS, both running Award with very few binary differences.

However, the ASUS board supports Socket 7, hence the VRM/VRW jumpers to switch voltage and some other minor differences.

The ASUS board also supports up to 1MB of L2 cache by using 15ns SRAM chips on the board, or you can opt for up to 512KB of COAST instead if you prefer.

Though the AST lacks the AV689 Audio/Video riser card the ASUS required, the ports are instead on the main board.

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.


Drivers and Manuals

  • Promise Ultra 100 TX2 Controller Card Driver 2.0.0210.36 for Windows 9x, NT, 2000, XP
  • Ultra100TX2_manual_en.pdf Promise Ultra 100 TX2 Controller Card Manual
  • crd8322b.pdf LG CRD-8332b Manual
  • An early ESS1788 AudioDrive Windows 95 driver (Might work on 98), exact date unknown.
  • SIS 6205 onboard graphics driver bundle, there are 7 disks inside this archive:
    • d1, DOS, NT 3.1, 3.5x, etc
    • d2, OS/2 Warp & Windows 95 (should work on 98 too)
    • d3, Windows 3.1 graphics & DCI
    • d4, PC-Video
    • d5, Video for Windows 1.1d
    • d6, double bytes OS/2 Warp
    • d7, OS/2 2.1


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

Requires a floppy disk drive or emulator.

  • 05567036.exe Advantage! 6xx System BIOS 1.00.15 (Unstable, I highly recommend using at least 1.03)
  • 05576034.exe Advantage! 62x System BIOS 1.03
  • 05576034.exe Advantage! 62x System BIOS 1.04