Story of my Packard Bell Pack-Mate 28 Plus

[retro-pc_user]

I have, in my collection of computers, a Packard Bell Pack-Mate 28 Plus with its Keyboard and Mouse that I purchased for $17 at a thrift store several months ago.

The system specs at the time were this:

Intel i486SX2-50
4MB On-board memory (64MB maximum)
Cirrus Logic CL-GD5428 with 1MB Video memory (2MB maximum) SVGA capable
No L2 cache (128KB or 512KB L2 cache supported)
1.44MB 3.5" Floppy Diskette Drive
210MB Western Digital Hard Drive
PS/2 Keyboard and Mouse
Packard Bell Navigation Software and most popular software (including Windows 3.1)
Packard Bell Monitor (there was one, but I didn't get it since they would've charged $20 for it)

The system was later on upgraded by the original owner or more features were added:

8MB RAM (4MB on-board and 4MB SIMM-72)
428.1MB Seagate Hard Drive (in place of the 210MB Western Digital)
3Com EtherLink III ISA Network Card
Windows for Workgroups 3.11 with MS-DOS 6.22 (or equivalent)

Later on after owning the system, I installed or upgraded the hardware to the following that's still in there today:
Epson SD-800 Dual Floppy drive (1.2MB 5.25" and 1.44MB 3.5")
Matshita 48x CD-ROM
Conner Tape Backup Drive (FDD interface)
2GB CF Card (has performance issues once in a while)
Aztech Sound Galaxy NX Pro (Yamaha YMF-262M OPL3, Sound Blaster Pro, Covox Speech Thing, and Disney Sound Source) Sound Card
Music Quest MIDI Clone Card by keropi (Rev. A) with the Roland MT-32 and my IBM ThinkPad R40 2682 with different MIDI choices (LA Synth to GM)
Lo-Tech Tandy 3-Voice ISA Card for Tandy games that uses the 3-voice polyphony chip
Intel i486DX2-66 (planning on getting the DX4-100 OD processor since only 5V is supported for CPUs, and not 3.3V)
32MB RAM installed (disabled the 4MB on-board due to speed latency issues)
2x AA Battery holder for the CMOS settings (gets picky if the battery is dead, and won't boot, even after saving settings in the BIOS setup, but I can boot from a floppy no issues)

I've had this system for several months and I can honestly say, this is the best system to have for older games, but the lack of L2 cache isn't good, but at least the chips are cheap to get, and upgrading the CPU from a DX2-66 to a DX4-100 OD will make games go faster. I have made cache disabling programs to temporarily disable the L1 and L2 cache for speed-sensitive games that support the Roland MT-32.

[retro-pc_user]

Did some upgrades along the way for my Packard Bell Pack-Mate 28 Plus within the past week or so:

Upgraded the CPU from the Intel i486 DX2-66 to a DX4-100 OverDrive I won off of eBay
Installed a Sound Blaster 16 CT2740 with a Yamaha DB50XG Daughterboard

[retro-pc_user]

Some more items that got installed, modified, or upgraded:

Modified the motherboard to support 3.3V processors (2 22uF 6.3V tantalum SMD caps, 1 fixed voltage regulator and mounting kit) and installed a battery socket for a CR1220 battery
Upgraded the CF card from 2GB to 4GB as the main HDD and copied everything over from the 2GB CF card
Repaired and installed the Creative Labs CR-563-B in place of the Apple 32x CD-ROM drive that was acting up
Tested Yggdrasil Plug-and-Play Linux Summer 1994 edition with the newly installed CD-ROM drive

Plans for the future:
Installing a Pentium OverDrive processor for faster operations
Figuring out why the L2 cache won't work in my system (it detects the L2 cache, but, the OS refuses to boot up).

[Fanatik]

Pretty nice, jack-of-all-trades setup you have there!

[GiGaBiTe]

Plans for the future:
Installing a Pentium OverDrive processor for faster operations
Figuring out why the L2 cache won't work in my system (it detects the L2 cache, but, the OS refuses to boot up).

As someone who owns a POD-83, I don't recommend it.

Pentium Overdrives weren't popular for multiple reasons, most notably incompatibility with various motherboards at the time, software on the platform it was designed for didn't support it, the expense and being much slower than fast 486/586 parts and even regular Pentiums. I have three 486 motherboards and all three have various issues with it. One won't properly recognize it, the CPU type shown in the BIOS is just corrupt text and it doesn't recognize the cache or run it at the correct clock speed. Another will see it, but doesn't recognize the cache and a third won't boot at all with it installed. In the two machines it does work in, it's no faster than my Am5x86-133s, certain games and Windows 95 actually run a lot slower on it.

The overdrive is a Pentium crippled to a 32 bit 486 bus, and it really degrades performance due to the loss of memory bandwidth. The low clock speed is another factor, if your software didn't take advantage of the FPU (and most desktop applications and games didn't, they were mostly integer based) then it is slower than a fast 486/586. There's really no use case for either of these CPUs besides if you need the faster FPU to play Quake or want to do something silly like try and run Windows XP on a 486 class machine.

If you want Pentium performance, I recommend buying a Pentium machine because for the price of a POD-63 or 83, you can get two Pentium machines.

[stecdose]

I have a Am5x86-P75, which is in fact a 486DX4 with 133MHz. I never had such a fast 486 system. I would classify this Am5x86 as one of the fastest 486-class CPUs every made. There are very few 150/160MHz version of this chip out there, also there are some Cyrix 486 CPUs a little faster.
Overclocking an Am5x86@133MHz to 150/160MHz is in most cases no problem at all - if you got a board, that supports it.
They are not that expensive as a Overdrive-CPU and they bring almost "full power" on 486-boards.

[retro-pc_user]

I had an Am5x86-P75 back in 2012 that was on another 486 motherboard I bought to replace the board that lost its BIOS chip. Also, I forgot to mention this: I upgraded the BIOS from the OEM Phoenix BIOS 4.03 v1.1a to Micro Firmware 4.05.10 and there are a few major advantages over the old BIOS (I have a backup of it, just in case):

1) Supports Write-Back cache processors, including the Pentium OverDrive 63 or 83 (no interposer needed)
2) Supports HDDs that are more than 8GB (cannot figure out why my 10GB HDD doesn't get detected, and I think its the ribbon cable that only has 2 ends on it: to the board and to the drive itself)
3) Supports the AMD AmDX5-133 (Am5x86-P75) processors (either the CPU and the ARIES Voltage Regulator, Kingston TurboChip, and Powerleap
PL/586-133)
4) Supports 128MB SIMM-72 (might test that theory)
5) Supports L2 cache* that are either 20ns (4x 256Kb (32Kx8) or 1Mb (128Kx8) 28-pin or 32-pin DIP SRAM) or 15ns (1x 256Kb (32Kx8) 1x 64K (64Kx1) 28-pin and 22-pin DIP SRAM or faster), whereas the older BIOS supports the 20ns and 15ns SRAM chips

Source: https://web.archive.org/web/20000817...ios/p4hs20.htm

* mine doesn't seem to like the L2 cache that's installed and I think its because of a mismatch as the system refuses to boot into Windows or DOS and it gives me an error message, even though the cache chips passed without issues on my laptop using my IC chip programming tool and software.

[retro-pc_user]

Forgot to note the 64Kx1 chip speed must match the other SRAM chip adjacent to it.

No cache:

U16, U19, U29, U32, U55, & U57 Empty

All memory is cacheable in L1 cache

128K cache:

U16, U19, U29, U32 have 32Kx8 SRAM, 20ns or faster

U55 has a 32Kx8 SRAM, 15ns or faster (or 25ns if unmultiplied CPU clock is 25MHz)

U57 has a 64Kx1 SRAM (same speed as U55)

Jcsz (J26) is open (no jumpers)

Only the first 32M is cacheable in L1 or L2 cache

512K cache:

U16, U19, U29, U32 have 128Kx8 SRAM, 20ns or faster

U55 has a 32Kx8 SRAM, 15ns or faster (or 25ns if unmultiplied CPU clock is 25MHz)

U57 has a 64Kx1 SRAM (same speed as U55)

Jcsz (J26) has jumpers on pins 1 to 2, and 3 to 4

Only the first 128M is cacheable in L1 or L2 cache (Since this is the maximum onboard memory, effectively all memory is cacheable)

[Agent Orange]

As someone who owns a POD-83, I don't recommend it.

Pentium Overdrives weren't popular for multiple reasons, most notably incompatibility with various motherboards at the time, software on the platform it was designed for didn't support it, the expense and being much slower than fast 486/586 parts and even regular Pentiums. I have three 486 motherboards and all three have various issues with it. One won't properly recognize it, the CPU type shown in the BIOS is just corrupt text and it doesn't recognize the cache or run it at the correct clock speed. Another will see it, but doesn't recognize the cache and a third won't boot at all with it installed. In the two machines it does work in, it's no faster than my Am5x86-133s, certain games and Windows 95 actually run a lot slower on it.

The overdrive is a Pentium crippled to a 32 bit 486 bus, and it really degrades performance due to the loss of memory bandwidth. The low clock speed is another factor, if your software didn't take advantage of the FPU (and most desktop applications and games didn't, they were mostly integer based) then it is slower than a fast 486/586. There's really no use case for either of these CPUs besides if you need the faster FPU to play Quake or want to do something silly like try and run Windows XP on a 486 class machine.

If you want Pentium performance, I recommend buying a Pentium machine because for the price of a POD-63 or 83, you can get two Pentium machines.

All of the above is true to a point. The OD was a cheap stop gap solution for those who desired the 486 performance but couldn't afford it. Think back to the 90's and try to recall that a top end 486 might cost you around 4 to 5 hundred dollars.

[retro-pc_user]

Some of the games, like Quake, does run better than the DX5-133 processor, however, the OverDrive has a 32-bit data bus width, which has a bottleneck in contrast to the other Pentium CPUs that has a 64-bit Data bus width, except double the L2 cache than the older Pentium processors and the same amount that's in the MMX CPUs.